Electromagnetic Interference to Flight Navigation and Communication Systems: New Strategies in the Age of Wireless

Abstract

Electromagnetic interference (EMI) promises to be an ever-evolving concern for flight electronic systems. This paper introduces EMI and identifies its impact upon civil aviation radio systems. New wireless services, like mobile phones, text messaging, email, web browsing, radio frequency identification (RFID), and mobile audio/video services are now being introduced into passenger airplanes. FCC and FAA rules governing the use of mobile phones and other portable electronic devices (PEDs) on board airplanes are presented along with a perspective of how these rules are now being rewritten to better facilitate in-flight wireless services. This paper provides a comprehensive overview of NASA cooperative research with the FAA, RTCA, airlines and universities to obtain laboratory radiated emission data for numerous PED types, aircraft radio frequency (RF) coupling measurements, estimated aircraft radio interference thresholds, and direct-effects EMI testing. These elements are combined together to provide high-confidence answers regarding the EMI potential of new wireless products being used on passenger airplanes. This paper presents a vision for harmonizing new wireless services with aeronautical radio services by detecting, assessing, controlling and mitigating the effects of EMI.

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Electromagnetic Interference to Flight Navigation and
Communication Systems: New Strategies in the Age of
Wireless
Jay J. Ely *
NASA Langley Research Center, Hampton, Virginia 32781
Electromagnetic interference (EMI) promises to be an ever-evolving concern for flight
electronic systems. This paper introduces EMI and identifies its impact upon civil aviation
radio systems. New wireless services, like mobile phones, text messaging, email, web
browsing, radio frequency identification (RFID), and mobile audio/video services are now
being introduced into passenger airplanes. FCC and FAA rules governing the use of
mobile phones and other portable electronic devices (PEDs) on board airplanes are
presented along with a perspective of how these rules are now being rewritten to better
facilitate in-flight wireless services. This paper provides a comprehensive overview of
NASA cooperative research with the FAA, RTCA, airlines and universities to obtain
laboratory radiated emission data for numerous PED types, aircraft radio frequency (RF)
coupling measurements, estimated aircraft radio interference thresholds, and direct-effects
EMI testing. These elements are combined together to provide high-confidence answers
regarding the EMI potential of new wireless products being used on passenger airplanes.
This paper presents a vision for harmonizing new wireless services with aeronautical radio
services by detecting, assessing, controlling and mitigating the effects of EMI.
I. Introduction to Aeronautical EMI: Lightning, HIRF and PEDs
t can be said that aviation and radio have grown up together. Since the 1920’s, radio technologies have
faithfully and continually enabled the ever-expanding need for aerospace vehicle navigation and communication
capability. Likewise, the need for reliable, secure communication, navigation and surveillance (CNS) and air traffic
management (ATM) for aerospace vehicles has continually driven improvements in radio technology. As aviation
has become more dependent upon radio for CNS, the effects of EMI have become ever more important. Since the
1920’s, with few exceptions, radio spectrum for aeronautical radio services has been coordinated and protected by
law, so as to minimize the potential of EMI from other radio services. However, EMI effects from lightning,
electrostatic discharge and high intensity radiated fields (HIRF) from radars and broadcast transmitters have resulted
in numerous aviation incidents and accidents over the years, and as a result, are now carefully considered in all
aspects of design and certification of modern avionics. Figure 1 shows an overview of the electromagnetic
environment in which a typical airplane flies.
While the lightning environment has not changed since the inception of aviation, flight operations now occur in
all weather conditions. In 1938, the National Advisory Committee for Aeronautics (NACA) established the
Subcommittee of Aircraft Safety, Weather and Lightning Experts to study lightning effects on aircraft and determine
what additional protective measures were needed. There is an interesting history of lightning strikes to airplanes,
sometimes with catastrophic effects. Today, lightning strikes have minimal safety impact upon airplanes due to well-
established FAA lightning protection regulations. The textbook “Lightning Protection of Aircraft” provides a
thorough technical guide to protecting aircraft from the effects of lightning, and an excellent history and
development of FAA lightning protection regulations.1
In the early 1960’s, it became evident that compact radio receivers, enabled by new transistor circuitry, and
carried on board airplanes by passengers, could disrupt the VHF Omniranging (VOR) and other navigation systems.
* Research Engineer, Electromagnetics & Sensors Research Branch, Mail Stop 130.
I

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To address this concern, the Radio Technical Commission for Aeronautics (RTCA) formed Special Committee 88.
Their report, RTCA/DO-119, “Interference to Aircraft Electronic Equipment from Devices Carried Aboard” was
published in 1963.2 This early effort resulted in FAR 91.19, controlling the use of PEDs on board aircraft and
recommended prohibiting the operation of portable radios during flight, and set the stage for restrictions on
passenger-carried PEDs that are still in effect today.
By the 1970’s, it also became evident that new digital flight control systems needed to be hardened to the effects
of HIRF emanating from broadcast towers, radars, and point-to-point radio links. In the United States, the
Department of Defense began to apply interface standard and system requirements for the control of EMI on aircraft
systems.3,4 These requirements are currently accompanied by numerous EMI-related handbooks relating to RF
environment definition, procurement guidelines, hazards, grounding, bonding and shielding. For commercial
aviation, the FAA worked with the RTCA to standardize environmental conditions and test procedures for airborne
equipment.5 Since the 1980’s, NASA has supported several studies documenting HIRF and EMI related events
reported by airplane flight crews.6,7
There are three basic elements to any EMI problem: Source, Path and Victim. This paper focuses upon the
dynamic EMI situation created by introducing intentionally-transmitting PEDs (“T-PEDs”, ie. cellular phones,
handheld radios, IEEE 802.11, etc.) into the airplane cabin. Because PEDs and T-PEDs are normally operated by
battery power when used on board airplanes, the path is primarily radiated, rather than conducted. (Some airplanes
are equipped with in-seat power for passengers, however the airplane supply systems are well regulated and
controlled to prevent conducted EMI to the aircraft electronic systems.) Given the physical size and transmit power
limitations of such devices, the primary EMI concern is for aircraft electronic systems (Victim), particularly CNS
radios.
Figure 1: Electromagnetic threats to aircraft systems
Figure 2: Three basic elements to any EMI problem.
Lightning & Static
Electricity
Groundbased or Shipboard
Transmitter (HIRF
Sources)
Airborne Transmitter
(Signal Sources: VHF
Com, TCAS)
PEDs
(Interference Sources)
Avionics
Bay
Airport Beacons & Communications
(Signal Sources: VOR, ILS, DME,
ATC, VHF Com)
Lightning & Static
Electricity
Groundbased or Shipboard
Transmitter (HIRF
Sources)
Airborne Transmitter
(Signal Sources: VHF
Com, TCAS)
PEDs
(Interference Sources)
Avionics
Bay
Airport Beacons & Communications
(Signal Sources: VOR, ILS, DME,
ATC, VHF Com)
Source
(T-PEDs) Victim
(Aircraft CNS
Radios)
Path
(Radiated or Conducted)

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II. On-Board Wireless: EMI Focus on Communication and Navigation Systems
Until the past 10 years or so, most airplane passengers were quite happy to leave their T-PEDs at home, packed
away, or at least turned off while on board. The explosive proliferation of wireless voice and data products, and the
increasing reliance of travelers upon them, now creates a serious safety concern for airlines and the FAA. Wireless
transmitters are increasingly being integrated into multifunction packages, often making it difficult for flight crews
and passengers to identify them as intentional transmitters.
A. PED EMI Reports
The most widely used, publicly available source of information about crew reports of airplane PED EMI events
is the NASA aviation safety reporting system (ASRS), which is administered under a memorandum of agreement
with the FAA. In March 2001, Ross reported a detailed analysis of ASRS data relating to PED EMI reports
occurring from 1986 to 1999.8 The study provided significant graphical analysis of PED types, airplane types, phase
of flight where incidents occurred, aircraft systems affected, whether incident was annunciated to the crew, and
degree of severity of the EMI event. Figure 3 (bottom) shows a graphical comparison of the number of PED EMI
incidents attributed to different kinds of PEDs. Clearly, mobile phones and laptop computers were the most likely
PEDs to be attributed as having caused an EMI incident. Figure 3 (top) shows a comparison of the aircraft systems
affected by PED EMI. Because of their necessary sensitivity to RF signals, aircraft CNS systems are expected to
have the highest sensitivity to PED EMI. Figure 3 confirms this expectation with alarming clarity.
Figure 3: NASA ASRS study from 1986 to 1999
(Bottom) PEDs affecting aircraft systems (Top) Aircraft systems affected

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B. U. S. and European Government EMI Regulations
1. FCC & IEC Rules for Products
In the U. S., the Federal Communications Commission (FCC) provides guidance for allowable signal emissions
from consumer devices. These are published and available on the Internet, in the U. S. Code of Federal Regulations
(CFR), Title 47 “Telecommunication”9. Within Title 47, there are numerous “Parts” and “Sections” that address the
full range of available product types. In Europe, the International Electrotechnical Commission (IEC) provides
guidance for allowable signal emissions from consumer devices. Measurement methods and test limits are provided
in the IEC CISPR 22 publication. To promote free trade and facilitate technology transfer across international
boundaries, the US and European Union (EU) have Mutual Recognition Agreements (MRA) which harmonize
measurement processes and test limits for spurious radiated emissions. Most other nations recognize or adopt either
the US or EU requirements applicable to PEDs. In any case, these product standards address devices intended for
use in residential, commercial, industrial or business environments. Both the US and EU further designate “Class
A” and “Class B”, where Class A devices are not intended for use in residential environments. Most consumer
products that are not intended to transmit RF power are certified to the more rigorous Class B requirements. T-
PEDs however, may include mobile phones, wireless local area networks (LANs), Citizen’s Band (CB) radios,
Family Radio Service (FRS) transceivers, General Mobile Radio Service (GMRS) transceivers, RFID tags and many
other devices. FCC rules for spurious radiated emissions of T-PEDs very widely, and are addressed in differenct
sections of the CFR.
2. FAA Rules for PEDs on Airplanes
In the US, the FAA provides guidance for allowable signal emissions from aircraft electronic systems. These are
not directly stated in the US CFR (as with the FCC limits for consumer devices). Instead, 14CFR91.21 states that
PEDs “may be used if the aircraft operator has determined that they will not cause interference with the navigation or
communication system of the aircraft on which it is to be used”10.
Further guidance is provided by Advisory Circular 91.21-1A, which states that designing and testing PEDs in
accordance to RTCA/DO-160D11 may constitute one acceptable method allowing their operation on board aircraft12.
RTCA/DO-160D, Section 21 contains measurement procedures and test limits to determine whether electronic
equipment emits excessive RF signals when installed in a particular location. The requirements are “harmonized”
with EUROCAE ED-1413, and therefore technically identical, and acceptable to Europe’s Joint Aviation Authorities
(JAA). Various equipment categories are defined in terms of location and separation between the equipment and
aircraft radio antennas.
Unfortunately, neither RTCA/DO-160 nor EUROCAE ED-14 address equipment (PEDs) that are carried on
board by passengers.
C. RTCA and EUROCAE PED Guidance
1. RTCA/DO-119
In 1963, RTCA/DO-119, “Interference to Aircraft Electronic Equipment from Devices Carried Aboard”
recommended prohibiting the operation of portable radio and television receivers during flight, and set the stage for
restrictions on passenger-carried PEDs that are still in effect today14. The study also addressed hearing aids and
portable dictating and recording machines. Most interestingly, the committee also recommended that specific
radiated emission limits be met for PEDs to be used on board airplanes, and furthermore, that such devices be
“suitably and conspicuously marked to provide a clear indication to flight crews that such devices have been
determined to be suitable for use aboard aircraft; and further: That such devices also be suitably marked internally
with a ‘WARNING’ legend to the effect that any modifications of circuitry, or the use of replacement parts which
do not meet the manufacturers specifications automatically voids the authorization for use of the device aboard
aircraft.”
The FCC however did not impose any regulatory limits on the radiated emissions of PEDs, in general, as a result
of the DO-119 recommendations.

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2. RTCA/DO-199
By the early 1980’s many airline passengers began inquire about the use of laptop computers, video recorders,
electronic games, calculators, paging receivers, medical devices, and even cellular telephones while on board.
Various airlines had differing policies about the allowance for use of different types of PEDs. Because some air
carriers prohibited the use of laptop computers on board, some computer magazines began to suggest that their
readers avoid particular airlines. In 1983, this lead to the Director of Quality Assurance and Chief Engineer of
Eastern Airlines requesting the RTCA to “generate a Minimum Operational Performance Standards document
against which manufacturers (of computers and other portable electronic devices) marketing their products for
airborne use, could test and label them as meeting this standard in a manner similar to the Underwriters Laboratory
sign of approval.” Soon thereafter, RTCA Special Committee 156 was formed.
On September 16, 1988, the Special Committee (SC) 156 report, RTCA/DO-199 “Potential Interference to
Aircraft Electronic Equipment from Devices Carried Aboard” was published.15 The report compiled nearly five
years of extensive efforts including operator surveys, aircraft radio susceptibility testing, aircraft coupling
measurements, PED emission testing, evaluation mitigation strategies such as shielding of windows, probability of
disruption analysis, and proposed radiation limits. The effort focused primarily on non-transmitting PEDs.
The committee concluded that PED EMI to aircraft radios CAN occur, however the probability is small.
RTCA/DO-199 made several important recommendations:
• Acceptable limits of radiation and associated test methods for PEDs be established
• The FCC specify a new classification for PEDs that may be operated on aircraft
• The FAA initiate a regulatory project to revise FAR 91.19
• Standardize reporting of suspected EMI be implemented by aircraft operators
The FAA subsequently adopted the proposed RTCA/DO-199 guidance, which resulted in the allowance of
hearing aids, heart pacemakers and electronic watches by passengers, but also the prohibition of use of T-PEDs.
The guidance went further to recommend that some non-transmitting PEDs may be used during cruise flight (not
takeoff and landing), such as audio or video recorders & playback devices, electronic entertainment devices,
computers and peripheral devices, calculators, FM receivers, TV receivers, and electronic shavers.
3. RTCA/DO-233
In 1992, the RTCA received an FAA request to revisit the issue of PEDs carried on board airplanes. This FAA
request was in response to a House Transportation Appropriations Bill that year that desired to resolve questions
about “recently devised PEDs, multiples of similar and dissimilar PEDs, and intentional electromagnetic radiators
such as remote control devices and cellular telephones.” On September 23, 1992, the formation of RTCA Special
Committee 177 was approved.
On August 20, 1996, RTCA/DO-233 “Portable Electronic Devices Carried on Board Aircraft” was published. 16
RTCA/SC-177 extended the technical work of SC-156 on nearly every front. The 30 PED EMI reports used by SC-
156 were supplemented with 34 more from the NASA ASRS, 40 more from the International Air Transport
Association (IATA) and 33 more to SC-177 directly. The FCC methodology for measuring PED emissions was
modified to be more compatible with avionics-type measurements. The methodology for measuring the path loss
between PEDs and airplane radio receivers now included swept-frequency approach, and was much more clearly
and thoroughly defined. The report considered both antenna-coupled “front door” and cable/aperture-coupled “back
door” interference to aircraft systems. Also, the report included analysis of Interference Probability and Operational
Interference Criteria. Unfortunately, SC-177 was unable to consider devices considered as intentional radiators (ie.
T-PEDs). The committee concluded that:
• PED EMI to aircraft systems CAN occur, however multiple independent conditions must be present.
• All PED operations should be restricted during critical phases of flight, as it is impractical for an aircraft
operator to determine whether any particular PED will not cause interference.
RTCA/DO-233 made several important recommendations:
• Prohibit the operation of T-PEDS on airplanes unless testing has been conducted to ascertain their safe use.
• Prohibit the operation of all PEDs during critical phases of flight.
• Continued testing of PEDs for spurious radiated emissions.

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• A public education campaign should be initiated by the airline industry and aircraft manufacturers to alerth
the public to the potential for harmful EMI to occur when PEDs are used on board airplanes.
• PED detection devices (installed or portable) should be designed and tested in commercial airplanes.
The FAA subsequently adopted the first two recommendations into FAR 91.21a.
4. EUROCAE/ED-118
After the publication of RTCA/DO-233, it became more and more evident, both in Europe and in the U. S. that
the use of mobile phones, wireless LANs and wireless personal area networks (PANs) on board airplanes needed to
be considered. In December 2000, Intel released a report “Safety Evaluation of Bluetooth Class ISM Band
Transmitters on board Commercial Aircraft”, which recommended that FAA and JAA regulations be modified to
specifically allow Bluetooth devices to be used during flight. In October 2001, the JAA issued Leaflet No. 29
“Guidance Concerning the Use of Portable Electronic Devices on board Aircraft”, which specifically permits
Bluetooth transmitters to be operated during non-critical phases of flight.
In early 2001, the European Organisation for Civil Aviation Equipment (EUROCAE) formed Working Group 58
with the following three objectives:
• To review the EMC issues related to the use of new technology PEDs and related installed services on
aircraft by evaluation and comparison of existing studies, measurement of data as necessary, and
production of a report.
• To propose technical and non-technical solutions for the operation of PEDs on board aircraft for the
aviation community, including standards and guidelines as appropriate.
• To provide guidelines to non-aviation standardization forums, in order to help them assist in the
maintenance of safety on board aircraft.
The working group was specifically tasked to “consider both intentional and unintentional radiations from PEDs,
and their coupling to electronic systems and antennas.” EUROCAE WG-58 has been the focal point of extensive
collaboration and technical work on PED EMI, and continues to meet regularly. Many of the WG-58 members
regularly participate in RTCA/SC-202 meetings and committees also. The EUROCAE WG-58 final report, ED-118
was released in November 200317. Some highlights of the ED-118 findings are listed here:
• The primary coupling risk for interference from PED spurious radiated emissions is through the system
antennas in the operational frequency bands of the aircraft receivers. PED’s should continue to be switched
OFF during take off and landing to avoid possible EMI.
• Low power intentional transmitters represent the same low risk as unintentional transmitters. Therefore,
passenger and crew use of these low power intentional transmitters may be allowed on the aircraft types
analyzed on a case by case basis.
• Recommend the prohibition of the use of any high power intentional emitters (EIRP of more than 100 mW,
like two way radios, satellite telephones, cellular telephones) during all phases of flight, unless their safe
use is demonstrated.
• A harmonization of the announcement between airlines and countries and an improvement of airline
announcements (several times, at better moments etc…) should be done.
• The use of PED detectors has not been retained as appropriate because the remaining risk that arises from
the potential unknown effects that the detectable devices may have to the aircraft systems, is considered
lower than the adverse effects that the technical and procedural problems of using a detector could develop
on the conduct of the flight.
• A concern is related to the introduction of a variety of PEDs including transmitters having owners, not
being aware of those transmitters or not in a position to disable them. Consequently, PED evolution is a
very important concern for any aircraft and hence, a continuous market monitoring is considered necessary,
to check wireless power emission and integration inside common PEDs.
• It is recommended that all standardization teams take the uncontrolled usage of PEDs onboard aircraft into
account and take action to assure the safe operation of aircraft.
• During this analysis the need for further studies and the continuous work on PED interference issues has
been identified. Studies should be related to the more detailed understanding of the interference risk in
relation to cavity effects, short distance influences, comparison between different EMC measurement

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procedures used in standards, statistical analysis of cumulative effects, UWB effects, potential interference
caused by uncontrolled demodulation of signals, and other knowledge gaps as identified in the report.
• Recommended the development of specific guidance to airframe manufacturers, PED manufacturers,
airlines and the traveling public for the use of PEDs. The working group therefore recommended the joint
development of additional guidance with RTCA SC202 and the creation of a common document based on
ED118.
5. RTCA/DO-294
In early 2003, the FAA requested that the RTCA initiate a new Special Committee to focus upon intentionally
transmitting PEDs. On March 21, 2003, the RTCA issued their first Terms of Reference for Special Committee 202.
RTCA SC-202 was tasked with developing guidance related to the use of portable electronic devices (PEDs) on
board air carrier aircraft. The guidance is intended to provide a means for authorities, aircraft operators, aircraft
manufacturers, PED manufacturers, and others as appropriate, to determine acceptable and enforceable policies for
passenger and crew use of PEDs. The primary focus for SC-202 is upon PEDs that transmit intentionally. The work
was divided into two phases:
• In Phase I, a near-term PED technology assessment, the committee focused on PED technologies that
currently exist.
• In Phase 2, a longer-term PED technology assessment, the committee will focus on emerging PED
technologies, for example ultra-wideband devices or pico-cells for telephone use on board aircraft.
During the first SC-202 meeting in May 2003, SC-202 divided the efforts in to four working groups. Working
Group 1 focused upon categorizing classes of PEDs, standards for characterization of their radiated emissions, and
compilation of RF emissions of representative devices. This group also addressed device failure modes that affect
RF emissions, and provide design guidance for making new devices that are more “aircraft friendly”. Working
Group 2 focused upon aircraft coupling and RF environment testing and analysis. Working Group 3 focused upon
aircraft system susceptibility to radiated PED emissions. Working Group 4 worked with the other 3 groups to
generate a risk assessment and compile documentation for the guidance document deliverable products of SC-202.
Phase I was completed with the publication of DO-294, Guidance on Allowing Transmitting Portable Electronic
Devices (T-PEDs) on Aircraft, issued October 19, 200418. The DO-294 findings and recommendations were
extensive. They are summarized here:
• The report provides a standard process for determining if the use of T-PEDs on aircraft could be allowed,
and acknowledged that current operational procedures instructing passengers to turn off all PEDs during
critical phases of flight, and turn off all T PEDs during all phases of flight are not fully effective.
• It may not be adequate to apply MOPS requirements directly when assessing individual aircraft system
susceptibility.
• The approach taken to aircraft RF protection assumes that an EMI environment would be presented to the
aircraft from outside the fuselage or from devices permanently installed on the airframe. On-board use of T
PEDs is introducing a new EMI source that could affect the performance of aircraft systems and requires a
reassessment of aircraft RF protection methods and procedures.
• There is insufficient data concerning path loss, transfer function, and coupling to characterize all aircraft
types and configurations.
• One of the difficulties associated with potential introduction of T PEDs to commercial aircraft is the lack of
consistent T PED marking or indication for its operating state, apparent to the users and the cockpit and
cabin crewmembers.
• Most emissions from T PEDs are significantly lower than the applicable FCC spurious emissions limits.
However, analysis performed during the development of this report confirmed that T PED spurious
emissions at the applicable FCC spurious emission limits could create a level of interference sufficient to
adversely affect the operation of some critical aircraft systems if the T PED is operated onboard the
aircraft. This analysis confirms earlier conclusions reached in DO-199 and DO-233.
• The system design for new CNS techniques and technologies should consider the impact of ubiquitous EM
energy.

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• In the long term, test standards such as ED14/DO160 Section 20 should be revised to account for the back
door interference environment created by on-board PEDs, including T PEDs. Minimum test level
requirements should be established to account for this new interference environment.
• The FCC should review 47CFR and the sections defining emissions limits for mobile and portable devices
(e.g. Part 15, Part 22, Part 24, Part 25, and Part 90 and others, as appropriate) with the aim of introducing
appropriate limits in the CNS bands for those devices that may be commonly operated on-board aircraft. In
accordance with the Terms of Reference, recommended RF emission limits will be developed as part of the
SC 202 Phase II activity.
• A repository of isolation, path loss, transfer function, and EM propagation behavior within aircraft types
should be developed. To the maximum extent possible, the data should be consistently measured, account
for variations of aircraft type and configuration, and be suitably documented. This recommendation
recognizes the practical difficulties in establishing and maintaining such a repository.
• A repository of T PED (and PED, in general) incidence reports should be established, along with a process
and mechanism for feedback of improvements into the regulatory and operational processes. These
incident reports should not be limited to EMI to essential or critical systems, but document any EMI to any
aircraft system.
• Operators desiring to allow T PED operations on-board aircraft should follow the process defined in this
document in order to develop appropriately detailed information concerning the risks, risk mitigation, and
residual effects of T PED emissions on aircraft operations. Operators desiring to allow PED or T PED use
onboard aircraft should follow those processes defined in this document for mitigation of human factors
effects on aircraft operations.
• Aircraft and equipment manufacturers should consider T PED usage in the interior of the fuselage as a
source of RF emissions, and design and test appropriately in order to demonstrate compliance with
appropriate regulations.
• Aircraft manufacturers should include T PED interference effects in flight safety analysis as part of aircraft
certification.
• Aircraft manufacturers and aircraft operators should collect and make available appropriate data for current
and future aircraft. Path loss data should be provided as an inherent element of the aircraft production or
modification process.
• The aviation industry should endorse, harmonize, and exploit the improved status and control mechanisms
for T PED devices as such mechanisms become available. These mechanisms are expected to result from
the actions of the electronics industry and other interested stakeholders, such as the recommendations
document to the consumer electronics industry entitled “Recommended Practice – Status Indicator for and
Control of Transmitters in Portable Electronic Devices (PEDs),” which is currently under development by
the PEDs Working Group (hosted by the CEA).
• Avionics manufacturers should study the prevailing intentional and unintentional EM signatures of PED
technologies for guidance on developing isolation criteria between the interior of the cabin and sensitive
equipment.
• All commercial aircraft should have a consistent, uniform, and ubiquitous indicator showing when use of
PEDs or T PEDs is permitted. This visual indicator should be omni-lingual; ideally a symbol accessible to
an international audience and coordinated with the CEA symbol developed in response to the above
recommendation.
• Aircraft manufacturers and operators should utilize the recommended practices when determining front
door IPL. Use of the recommended practices will ensure that consistent, repeatable results are obtained that
are directly comparable.
• Care should be exercised when utilizing available path loss data for similar aircraft type comparisons and
assessments.
• Additional efforts are needed to better understand and quantify back door coupling on existing and new
aircraft types. Collecting data to quantify the back door coupling concerns should be organized and
pursued.
• ICAO-member States' air-safety investigative authorities should provide awareness training to their
investigators regarding what circumstance[s] the performance of an aircraft involved in an incident or
accident could be related to electromagnetic interference and provide guidance (such as checklists and
resource contact information) for an effective assessment of potential EMI involvement in an occurrence
scenario.

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• Significant additional effort should be applied to better quantify the multiple equipment factor (MEF).
Approaches may consider coupling path, failed T PEDs, T PED transmit signal protocols and aircraft
receiver characteristics.
D. NASA LaRC Collaborative EMI Work with Universities, Airlines, RTCA & FAA
1. Airplane Coupling Path Measurements
Figure 4(a) illustrates typical radio receiver interference coupling paths and Figure 5(b) shows a setup for
conducting interference path loss (IPL) measurements. IPL is defined as the measurement of the radiated field
coupling between passenger cabin locations and aircraft communication and navigation receivers, via their antennas.
The setup shows a tracking source is used to provide RF power to the transmit antenna, and a spectrum analyzer is
used to measure the signal received by the aircraft antenna. The frequency-coupled spectrum analyzer and tracking
source pair allows for frequency sweeps, resulting in more thorough measurements and reduced test time. Swept
CW was preferred over discrete frequency measurement, according to RTCA/DO-233. A pair of test cables is used
to connect the instruments to the aircraft antenna cable and to the transmit antenna. An optional amplifier may be
needed to increase the signal strength depending upon the capability of the tracking source and the path loss level. A
preamplifier may be needed in the receive path near the spectrum analyzer for increased dynamic range. This pre-
amplifier (not shown in Figure 4.1-3) may be internal to the spectrum analyzer.
From 1996 to 1998, the FAA Office of Aviation Security R&D conducted a multiyear assessment of the
potential use of on-board EMI to upset critical and essential aircraft functions. The effort utilized engineering
expertise from Veda Incorporated and Eagles Wings Incorporated (EWI) to perform measurements on a FAA
CV580 airplane located at the William J. Hughes Technical Center in Atlantic City, New Jersey. The tests
established the IPL measurement techniques used by RTCA DO-233, and resulted in several important findings.
Some of the findings are listed here19:
• Reflections from wing and engine are not significant to passenger cabin-to-aircraft antenna coupling data.
Figure 4: (a) A typical radio receiver interference coupling path for a top mounted aircraft antenna. (b) A
typical setup for conducting an IPL measurement.

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• Effect of coupling through cockpit door was determined to be insignificant for VOR, VHF Com, UHF
Com, Distance Measuring Equipment (DME) and the Global Positioning System (GPS) aircraft radios.
The effect of Glideslope (ILS Glideslope) coupling through the cockpit door was determined to be
secondary to coupling through passenger cabin windows.
• Mode Stirring techniques were found to be helpful when obtaining data at limited measurement locations.
• Applying aluminum tape to all aircraft windows resulted in up to 35 dB increase in IPL.
• Direct interference effects were demonstrated to aircraft VOR, VHF Com, UHF Com, Glideslope and GPS
when using a low-powered transmitter (spectrum analyzer tracking source).
In the Fall of 1999, NASA extended the FAA work with Eagles Wings Incorporated (EWI) to perform IPL
measurements on B747-400 airplanes located in Las Vegas, Nevada, and San Francisco California. This work was
extended to evaluate the effect of PED signal propagation over the curved portion of different diameters of aircraft
fuselages. Some of the findings are listed here.20
• Identified nose-mounted antennas on the B-747 (Localizer, Glideslope) to have very low coupling loss to
the passenger cabin lower front deck.
• Identified top-mounted antennas on the B-747 (TCAS, ATC, VHF Com, SATCOM) to have very low
coupling loss to the upper passenger cabin area.
• Found that IPL from passenger locations outside the airplane (ie. jetways and stairs) are often lower than
from inside the airplane.
• Coupling from the passenger cabin to aircraft antennas is minimized when it occurs over fuselage sections
of lower curvature.
• IPL measurements should be performed on smaller regional jets and turbo props.
In the Spring of 2000, EWI teamed with Delta Airlines to address a NASA Research Announcement, and
proposed a study entitled “Operational Malfunction Mitigation on Commercial Aircraft Communication/Navigation
Systems due to Close-in ElectroMagnetic Interference Threats”. In July 2000, NASA Langley research center
entered a Cooperative Agreement with Delta airlines to measure RF coupling from the passenger cabins of various
aircraft types. Additional data was obtained to determine the cause of excessive antenna-to-receiver path losses
found in a previous measurement program. Airport frequency spectrum environment were measured in
ramp/boarding/lounge areas outside the aircraft. Ambient RF environment data was collected from 20 MHz to 2.5
GHz. Methods of measuring RF emissions from PEDs were evaluated. PED threat levels and aircraft coupling
factors were compared to operationally required com/nav signal levels to determine the potential for interference.
Technical findings from the measurement and analysis effort were used to develop improved operational procedures
and policies for identifying, resolving and mitigating PED EMI conditions.
In 2003, the agreement was modified to facilitate airline support of RTCA SC-202 activities, to collect more IPL
data on multiple B-757 airplanes, to perform a statistical analysis of IPL, to collect signal level data from taxiways
in typical airport environments, and to collect further radiated emission data from PEDs. The cooperative agreement
was extended to March 2005, and provided significant useful data to RTCA SC-202 and practical insight into airline
maintenance and flight operations, as well as an understanding of airline perspective regarding EMI issues (ie.
aircraft certification and maintenance, fault isolation, troubleshooting and recovery, and incident reporting). Several
of the Delta reports are available on the NASA Technical Report Server website.21 Figure 5 shows a sampling of
measurement activity and data related to the Delta Airlines Testing.

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On September 11th, 2001, the terrorist attack caused many airlines to park flight-ready airplanes at desert storage
facilities. During the Spring and Summer of 2002, this situation provided an opportunity to extend the available
database of radio frequency (RF) coupling losses from various passenger-cabin locations. Evaluation of the
NASA/Delta/EWI measurements had identified a concern that path loss data collected and reported by different
personnel, on different but similar airplanes may have some degree of variability.
• Duplicate sets of path loss data were obtained on multiple, identical Boeing 737 and Boeing 747 aircraft, to
establish repeatability of the measurement process and to identify any differences related to subtle aircraft
configuration changes.
• Path loss measurements were also performed using an alternate, electrically small biconical antenna for the
VHF band. Previously, all IPL measurements had been performed with tuned dipole antennas, which are
not very rugged, and are too large to be easily manipulated in most airplane passenger cabins.
• An Eclypse handheld Standing-Wave-Reflectometer was demonstrated to reveal aircraft radio cable and
antenna faults. The device required minimal operator training, and showed definite promise for allowing
simple assessment of aircraft RF pathways without antenna removal (which is operationally expensive).
The Eclypse meter was a direct product of commercialization of NASA technology for troubleshooting
cable faults on space shuttle orbiters (NASA Tech Briefs Technical Support Package KSC-11866, U.S.
Patent #5,977,773).
• Conductive door-seam treatments and window films were evaluated to test aircraft modifications for
minimizing interference coupling from passenger transmitters to aircraft radios via their antennas.
• In a supplemental test, Ultrawideband (UWB) electromagnetic interference (EMI) effects were observed on
the Air Traffic Control Radio Beacon System (ATCRBS), Traffic Collision Avoidance System (TCAS),
Instrument Landing System (ILS) Localizer and ILS Glideslope aircraft systems22,23. The interference
effect was observed when operating the UWB device at numerous locations within the passenger cabin. A
video was made of the interference. This lead to an extensive direct EMI effects UWB testing program
discussed below.
Figure 5: Left: Instrumentation setups and measurements of IPL. Right: IPL data collected along a cross-
sectional plane of the passenger cabin of a B-757 airplane.
Instrumentation Rack
Antenna
Reference
Measurement
Window Coupling
Inside
Coupling
Avionics Rack
Connection Delta B-757 Airplane
B-757 Coupling from Cabin to VOR Antenna

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Data from this effort has continued to provide useful insight into airplane IPL characteristics for computational
modeling, estimation of multiple equipment factor, statistical analysis, evaluation of shielding techniques, and
comparison to other airplanes. 24,25,26,27
2. Spurious Radiated Emission Measurements from T-PEDs
In the Spring of 2001, NASA LaRC entered into an Interagency Agreement with the FAA and teamed with the
University of Oklahoma Wireless EMC Center to develop a radiated emission measurement process for CDMA (IS-
95) and GSM (ETSI GSM 11.22) wireless phones. Spurious radiated emissions were characterized from devices
tested in both semi-anechoic and reverberation chambers, in terms of effective isotropic radiated power. Eight
representative handsets (4 GSM, 4 CDMA) were commanded to operate while varying their radio transmitter
parameters (power, modulation, etc.). The NASA report28 provided a detailed description of the measurement
process and resulting data, which may subsequently be used by others as a basis of consistent evaluation for
cellular/PCS phones, Bluetooth, IEEE802.11b, IEEE802.11a, FRS/GMRS radios, and other portable transmitters.
Aircraft interference path loss (IPL) and navigation radio interference threshold data from numerous reference
documents, standards, and NASA partnerships were compiled. Using this data, a preliminary risk assessment was
provided for CDMA and GSM wireless phone interference to aircraft localizer, Glideslope, VOR, and GPS radio
receivers on typical transport airplanes. The report identified where existing data for device emissions, IPL, and
navigation radio interference thresholds needs to be extended for an accurate risk assessment for wireless
transmitters in aircraft. Some findings are listed here:
• None of the four CDMA and four GSM wireless handsets tested would individually be likely to interfere
with aircraft VOR, LOC, GS, or GPS navigation radios.
• If a CDMA or GSM wireless handset radiated spurious signals equal to the maximum allowable FCC
limits, it would result in large NEGATIVE safety margins, even when considering “reasonable minimum”
radio receiver interference thresholds:
Figure 6: (a) Photograph of 6 B-737 airplanes used for IPL measurements. (b) Photograph of one of 4 B-747
airplanes used for IPL measurements. (c) UWB source used for EMI testing. (d) Photograph of ILS
Localizer and Glideslope antennas inside a B-747 radome.

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• Each handset was commanded according to an extensive matrix of operational modes, while spurious
radiated emissions were measured. CDMA handsets were commanded to multiple power output levels,
puncture rate settings, and vocoder rate settings. GSM handsets were commanded to multiple power output
levels, DTX and DRX, and speech CODEC settings. While the operating mode often resulted in
discernable differences in the spurious radiated spectrum, dominant spectral components did not vary
appreciably due to mode changes. Interestingly, repeatedly turning the handset power ON-OFF caused the
most significant changes in the spurious radiated spectrum.
• It was demonstrated that intermittent spurious radiated emissions would sometimes increase up to 10 dB
when touching the keypad, touching the antenna, or retracting the antenna on the test handsets. However,
when compared to the highest emission levels in all operating modes, these manipulations resulted in only a
3-dB increase for the highest emission levels.
• It was demonstrated that GPS- and DME-band emissions occur, due to intermodulation between GSM and
other wireless handset types, when the handsets were placed in close proximity to one another. It was
identified that other combinations of common passenger transmitters could potentially produce
intermodulation products in aircraft communication and navigation radio-frequency bands.
• It was identified that the FCC does not restrict airborne use of PCS wireless handsets. FCC limits for
spurious radiated emissions for PCS handsets are the same as for cellular handsets. However, only cellular
handsets are restricted from airborne operation by the FCC (47CFR22.925 [60]).
In 2003, the reverberation chamber measurement processes developed by NASA were extended to address
Wireless Local Area Network devices and two-way radios, under a modification to the FAA/NASA Interagency
Agreement. Spurious radiated emissions in aircraft radio frequency bands from several wireless network devices
were compared with baseline emissions from standard computer laptops and personal digital assistants. In addition,
spurious radiated emission data in aircraft radio frequency bands from seven pairs of two-way radios were provided.
A description of the measurement process, device modes of operation and the measurement results were reported. A
risk assessment was provided for interference from wireless network devices and two-way radios to aircraft systems,
including Localizer, Glideslope, Very High Frequency Omnidirectional Range, Microwave Landing System and
Global Positioning System. The report compared the interference risks associated with emissions from wireless
Figure 7: NASA Langley Research Center HIRF laboratory setups for measuring spurious radiated
emissions from CDMA, GSM and other mobile phones and PEDs.
Semi
Anechoic
Chamber
Control
Room
Experime
nt Room
Reverberation
Chambers
Ramp
Ram
p
Gtem
Offices Office
s
HIRF Laboratory
Semi
Anechoic
Chamber
Control
Room
Experime
nt Room
Reverberation
Chambers
Ramp
Ram
p
Gtem
Offices Office
s
HIRF Laboratory
Semi-Anechoic Chamber Reverberation Chamber
Base Station Simulators
Multiple Phone
Interaction Testing
Emission Measurement
Workstation
3 Rotational Orientations

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network devices and two-way radios against standard laptops and personal digital assistants. Existing receiver
interference threshold references are identified as to require more data for better interference risk assessments.
• It was determined that WLAN device spurious emissions are not any worse (not higher) than spurious
emissions from computer laptops/PDAs in the VHF-Com band.
• The emission levels from WLAN devices and laptops/PDAs are lower than the FCC limits, but they can be
higher than RTCA/DO-160D Category M limits.
• Spurious emissions in GS band from FRS and GMRS two-way radios can be 11 dB higher than RTCA/DO-
160D Category M limit, and 4 dB higher than the maximum laptop/PDA emissions in the same band.
• Interference threshold data are inadequate for thorough assessments the threat from PED-type EMI.
• Based on the limited interference threshold data, safety margin calculations were conducted. The results
show that the safety margins can be negative or positive depending upon the interference thresholds value
and the minimum IPL data (the lowest or the average) used.
In 2004, NASA built upon the process and results from previous efforts, and evaluated newer generation mobile
phones (again under a new modification to the FAA/NASA Interagency Agreement). Two of the latest and most
popular technologies used in the US were the CDMA2000 1xRTT (1x Radio Transmission Technology) and the
GSM/GPRS (General Packet Radio Service). In addition, phones operating in the higher frequency 1900 MHz band
were addressed. Emission measurements were conducted on 33 wireless phones of various design configurations by
different manufacturers. These mobile phones were more representative of those available in today’s market place
than the mobile phones tested previously by NASA. Testing in both voice and data modes was conducted. The
Figure 8: Wireless LAN & PAN devices and FRS & GMRS Radios measured for spurious radiated
emissions
802.11A 802.11B Bluetooth
GMRS Radios
FRS Radios

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results were compared against baseline emissions from laptop computers and personal digital assistant devices that
are currently allowed to operate on aircraft. The following observations were made:
• The 33 wireless phones tested did not generate higher emissions in most aircraft radio bands than standard
laptop computers. An exception is the MLS band, where the emissions from the phone exceeded the
emissions from the laptop computers. However, the safety margins in this band were positive for all
devices.
• Spurious emissions from the wireless phones tested were below the aircraft installed equipment emission
limits (RTCA/DO-160 Category M). They were also below the FCC Part 15 limits for unintentional
transmitters such as laptop computers.
• The calculated safety margins can be negative or positive depending upon the interference thresholds
(minimum or typical) and the minimum IPL data (the lowest or the average) used.
• It is generally observed that in lower frequency bands (VHF-Com, LOC, VOR and GS), each mobile
phone’s maximum emissions are similar regardless whether it is operating in the cellular or PCS bands.
This is not the case for higher frequency bands (TCAS, DME, GPS or MLS).
• The measured emissions in the voice and data modes are generally similar for any single device (within 2-5
dB) in most cases.
A new analysis of previously compiled and reported IPL summary data was used to provide a conservative
bound for the multiple-equipment-factor (MEF). This factor is an estimate of the cumulative interference effects to
aircraft radios if there are multiple similar devices present on the airplane. An approach was developed to provide
an estimate of the upper bound on the front-door interference effects of multiple PEDs. This approach sums the
interference powers at the receivers after scaling each device’s emission by the IPL corresponding to its location.
Using full-aircraft B737 IPL data, conservative upper bounds were derived for LOC, VHF and TCAS on a B737
airplane. The following observations were made:
• MEF determined using the windows-only IPL data were within one dB of the MEF determined using full-
aircraft seat data.
• Conservative bounds for MEF for the systems measured were between 10 dB and 14 dB for LOC, VHF-
Com, VOR and GS.
• The effects of additional seats on the MEF calculation diminished rapidly with the increased distance
between the seat locations and the windows/doors.
In 2005, the FAA/NASA Interagency Agreement was again modified to develop a test methodology for
assessing interference risk of active RFID devices to aircraft communication and navigation radios. RFID tags have
been evaluated by air shipping companies, the U. S. Department of Defense and airlines to track luggage and to
evaluate how well tags hold data and can be read when installed on nonrotating engine components.29 NASA
purchased active tags and associated interrogators (ie. “readers”, “signposts”, etc.) from over five different
manufacturers. A major challenge in this ongoing testing is to coordinate measurements of the spurious radiated
emissions to when the tags are actually transmitting. The final report is expected in December 2005.
Figure 9: 3G mobile phones measured for spurious radiated emissions
3G Mobile Phones

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3. Direct Effect UWB Testing on Airplanes
Ultrawideband (UWB) transmitters are one day expected to be integrated into a wide variety of portable
electronic devices (PEDs) that passengers routinely carry on board commercial airplanes. The aeronautical
community has been concerned as to whether evolving FCC UWB rules are adequate to protect legacy and emerging
aeronautical radio systems from electromagnetic interference (EMI) from emerging UWB products. In a joint effort
between NASA (Headquarters, Langley Research Center, Glenn Research Center, Ames Research Center), the
FAA, United Airlines, EWI, Sky West Airlines and the U. S. Department of Transportation, specific UWB-type
EMI signals were introduced to radio systems installed on airplanes, and to observe effects in the same context that
they would appear to flight crews, in a realistic operational signal environment. Because all UWB threat signals
were calibrated referenced to FCC 15.209 limits for unlicensed transmitters, this was the most extensive PED EMI
direct effects testing ever performed on commercial airplanes. Extensive details regarding this work are reported in
a NASA Technical Publication.30
Here is a brief summary of the test results:
• Aeronautical radio systems operating below 960 MHz are at risk to EMI from handheld UWB consumer
products meeting existing FCC requirements.
• Aeronautical radio systems operating above 960 MHz were not affected by UWB emissions at levels
meeting FCC UWB limits (15.519, handheld systems), when emitting from within airplane passenger
cabins.
• UWB modulation cannot be assumed to reduce the likelihood of harmful interference.
• Numerous UWB PRF selections were shown to be effective at interfering with aircraft radios.
• UWB product effects upon onboard wireless systems remain unknown. (Such onboard systems would
include cargo smoke detection, cabin communications and surveillance systems.)
Specific EMI effects observations are discussed in the next section. Aside from the test results, this study exposed
several additional EMI-related safety and security concerns.
• Simultaneous EMI to multiple radio systems: EMI from a single PED can interfere with all parallel
redundant aeronautical radio systems if they are tuned to the same radio channel. In addition, wide
Figure 10: Assortment of active RFID tags and test rig for NASA spurious radiated emission measurements
RFID Tag Motion Test Rig
Some of NASA’s Typical Active RFID Tags

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bandwidth EMI signals may cause interference to several different COM/NAV systems, operating on
different channels, simultaneously. Thus, the redundancy designed to protect against component failure
may not be effective in protecting against EMI.
• Hidden performance impairment due to EMI: COM/NAV system performance degradation effects can
occur up to and including system failure on some aircraft systems without the flags, annunciations, or
system status displays changing to indicate system failure of loss of capability.
• Interdependencies of aircraft communication, navigation & surveillance (CNS) Systems: Some systems
were observed to have their performance degraded by interference effects propagating from other systems.
• Non-standardized displays of navigation and flight information make it impossible to describe the airline-
wide effects of EMI expected on particular COM/NAV systems from one aircraft type to another. The
number, placement, size, and information content of COM/NAV system status and data displays are highly
variable. Even the names of the primary displays and controls are not standardized among aircraft
manufacturers or between aircraft types from some individual manufacturers.
• No crew procedure exists to identify, report, and resolve COM/NAV system EMI events that may be due to
spurious (aeronautical radio frequency band) radiation from PEDs.
• The present aircraft certification process does not address vulnerability to EMI from PEDs.
• No specific detection devices are in place to alert the crew to the presence of EMI or degradation that may
be occurring.
• The correlation between available test data (ground tests only) to actual flight conditions needs more study.
III. Evidence of EMI: What EMI Effects May Look Like To a Flight Crew
The study of UWB direct effects on COM/NAV systems provided a unique opportunity for observing anomalous
aircraft system behavior that may result from EMI. In order to manage the operational impact of EMI effects, it is
first necessary to describe them from a pilot’s viewpoint. A general description of EMI effects for several
COM/NAV systems observed during the UWB test project is provided here, and operational methods to handle
these effects are explored.
The effects on VHF-COM varied with specific EMI signal modulation types, as well as the particular model of
aircraft radio. Some VHF radios went suddenly silent without any indication of interference prior to reaching the
upset threshold or any alerting to the crew. Other VHF radios experienced audible distortion and unwanted noise as
the interfering signal power level increased, until some point at which voice communication was judged to be
unusable by the pilot. No specific failure flags, indications or audible/visual warnings occurred during EMI testing
for VHF Com. VHF radio failure effects occurred in a similar manner and at a similar level when the EMI signal
was transmitted from numerous locations over much of the passenger cabin. Thus for situations where unwanted
noise due to EMI is occurring, crew selection of an alternate VHF COM system would not likely mitigate the effect,
but would provide confidence that the effect is being caused by EMI rather than system failure.
For VOR and ILS (Localizer and Glideslope), visible variations in both vertical and horizontal indicators were
observed to be caused by the EMI signal. The variations were of two types: offsets from the course or glideslope
and/or fluctuations. Both effects ranged from tenths of a mark (diamonds, dots, or lines) to 2 marks. “Operational
EMI Failure” was declared upon blanking (or stowing) of the indicator needles on the navigation displays. This
may or may not have been indicated by a failure flag, and may have appeared as though the reference signal was too
weak to be received (i.e. out of range). “System EMI Failure” was indicated by a VOR, Localizer or Glideslope
failure flag appearing on a navigation display. Due to EMI source path loss differences, effects were generally more
severe on one particular aircraft system versus redundant systems, therefore, crew operational procedures that
include checking redundant system data may be helpful for mitigating EMI impact. The audio (Morse-code)
identifiers were sometimes affected first, sometimes simultaneously with the visual effects, and sometimes not at all.
Therefore the audio identifiers provided no sure indication of whether the indicated direction was disturbed.
The most common EMI effect on DME was blanking of the displayed DME data. Due to EMI source path loss
differences, effects were generally more severe on one particular aircraft system versus redundant systems,
therefore, crew operational procedures that include checking redundant system data may be helpful for mitigating
EMI impact. On some systems, using live DME signals, the indicated distance to that site varied up to 1 nautical
mile when an EMI signal was present. The audio (Morse-code) identifiers were sometimes affected first, sometimes
simultaneously with the displayed effects, and sometimes not at all. Therefore the audio identifiers provided no sure
indication of whether the indicated direction was disturbed. Occasionally, the “ATC Fail” light illuminated during

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DME EMI tests. No specific failure flags, indications or audible/visual warnings occurred during UWB EMI
testing for DME, other than the loss of DME data.
For the ATC Transponder, EMI effects were not observable by the crew up to and beyond the point of an “ATC
FAIL” indication. The best results were obtained when monitoring ATC reply efficiency using a ramp test set.
Operational EMI Failure was defined as a drop below 90% in aircraft replies to interrogations.
In some cases, distant TCAS airplane images disappeared off the crew display due to interfering signals. On
some systems the TCAS fail light and/or the ATC fail light preceded the loss of airplane images. On some systems
the fail lights did not illuminate with any event. On some aircraft, the only indication of an ATC failure was that the
red “reply” light stopped blinking. From these observations, it may be beneficial for crew operational procedures to
include checks of the ATC reply indicator if PED EMI is suspected. Failures took seconds to minutes after
illumination by PED emissions to occur and seconds to minutes to recover after removal of the interfering signal.
EMI effects to ATC and TCAS receivers gradually increased with higher EMI signal power levels. Thus, PED EMI
is more likely to affect system processing of TCAS interrogations and ATC replies from distant airplanes rather than
nearby airplanes.
For GPS, the type and extent of system status data varied greatly from aircraft to aircraft. Most aircraft GPS user
interfaces simply provided “No Computed Data”, or “System Fail” warnings, and number of satellites tracked. Less
commonly, some airplane GPS displays included signal health information about each satellite in view. Flight
operational procedures should include training about how GPS data is used by the aircraft systems and how to
determine degradation of GPS signal reception. For one airplane system, it was observed that increasing the EMI
power level caused the GPS system to shift into reduced capability modes, thereby providing less information (no
altitude) and poorer fix accuracy. On one airplane, EMI resulted in aural commands to “pull up” emanating from
the ground proximity warning annunciator. Presumably, this may have been caused by loss of GPS position
accuracy, however it is uncertain whether a pilot encountering such a warning would consider the cause to be PED
EMI. Secondary effects to autopilot, flight director, flight management system, etc. caused by loss of COM/NAV
data are not considered in these descriptions. The reaction of pilots to the aural and visual symptoms of EMI
interference seen in the tests is likely to vary widely by aircraft type, COM/NAV system type, phase of flight, flight
conditions, pilot technical knowledge of the system, and pilot flying experience. One of the reasons offered for why
many pilots have never seen significant EMI effects is that the probability of channel and time coincidence between
PED interference and specific COM/NAV systems channel usage today is very low. This may not be the case as
UWB and other emerging PED radio technologies become ubiquitous.
Operational availability of the SATCOM system was not readily apparent to the crew. SATCOM output is used
as a part of the automated radio system. It was possible for the on-board PED system to keep the satellite system
searching indefinitely for a clear channel with the PED system transmitting from inside the passenger cabin.
Therefore it would be helpful for crew operational procedures to include periodic checks on SATCOM status.
IV. EMI Detection and Mitigation for Aviation Safety and Security.
A. EMI: Inadvertent or Malicious?
Until recently, it was generally assumed that EMI situations that occur on commercial airplanes would be caused
unintentionally. Today’s increased awareness of global terrorism, and the expanding media coverage of EMI
weapons, makes it more likely that EMI weapons may be used against airplanes and CNS/ATM infrastructure in the
future. Figure 4 shows a sampling of magazine coverage of this threat.
On February 25, 1998, the U. S. Congress held a Joint Economic Committee Hearing on Radio Frequency
Weapons and Proliferation. In one of the recorded statements, Dr. R. Alan Kehs of the Army Research Lab asked a
profound question: "At what point do common civilian electronic devices become weapons?"31

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B. EMI Detection
In August 1996, RTCA Special Committee-177 recommended “Government and industry should pursue research
into the design and feasibility of using devices designed to detect emissions that produce electromagnetic
interference from PEDs within aircraft cabins”. Soon after publication of the RTCA/DO-233 report, the FAA
entered into a Small Business Innovative Research (SBIR) contract with Megawave Corporation (Boylston,
Massachusetts) and Embry Riddle Aeronautical University (ERAU, Daytona Beach, Florida) to design a system for
the detection and localization of potentially harmful radiation from PEDs carried onboard aircraft. The system was
designed to monitor the radio spectrum from 50 to 2000 MHz, with up to 64 sensors distributed throughout the
passenger cabin of an airplane. Unfortunately, funding and sponsorship of the system dissolved before a prototype
could be built. To date, the Megawave/ERAU design remains the most comprehensive approach for a PED detection
system. Details of the design were presented at the 1998 Digital Avionics Systems Conference32. Aside from a
system designed exclusively for installation on aircraft, other PED detection options have become available since
the RTCA/DO-233 recommendation. Holaday Industries (now a part of ETS-Lindgren) markets a Cell Alert system
for detection and alerting of wireless phones that may be activated in the hospital environment, but are unauthorized.
Details may be found at http://www.emctest.com/Holaday/pa3.htm. Cellbusters.com, in Phoenix, Arizona,
manufactures the Cellbuster®, which appears similar to the Cell Alert®, and is marketed for use in power plants,
airports, medical clinics, computer rooms, transportation operations, industrial plants, control rooms, laboratories,
financial institutions, courthouses, government buildings, legal offices, embassies, and defense facilities. Details
may be found at http://www.cellbusters.com. Channel Business Services, of Hamburg Germany, markets the
Mobifinder® mobile phone detector, for use in airplanes, airports, hospitals, doctor’s offices, medical laboratories,
near fuel depots and gas stations, and other security areas. Further details may be found at
http://www.mobifinder.de/english/products/index.html. Alitalia Airlines has evaluated the Mobifinder® as a tool
for the chief cabin attendant on some flights in 199833, and found that it was often difficult to identify the exact
location of the unauthorized transmitter. The Alitalia evaluation team recommended that multiple Mobifinder®
units be used to increase the likelihood of threat localization, to heighten passenger awareness to the potential
hazards of wireless phones, and to aid the flight crews in resolving suspected EMI events. Other PED detection
products are also likely to be (or become) available. Narda East (L3 Communications), in Hauppauge, New York
has advertised the portable AirGuard® PED sensor, for detecting PED emissions that may be present in aircraft
communication/navigation frequency bands, and has demonstrated a prototype unit at NASA LaRC. The Narda
approach is subtly different from the other approaches because it focuses on excessive PED emissions in aircraft
frequency bands, rather than detecting specific T-PED frequencies that have been designated as unauthorized for use
Figure 11: Sample of Magazine coverage of EMI Weapons and Terrorism

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onboard airplanes. This significant difference was identified in the Megawave/ERAU study, and acknowledged to
be of significant design concern for an operational system to provide a high probability of detecting potentially
harmful PED signals, while not burdening flight crews with false alarms. The most difficult issues relating to the
detection of unauthorized PEDs are less technical than financial and operational. Any piece of electronic equipment
an airline designates for use onboard their aircraft must be certified for flight worthiness according to FAA
regulations. Certification may add significant cost over the base price of the equipment. Also, airplanes can only
generate revenue when they are carrying passengers. Thus, an installed PED detection system is subject to the
additional cost of lost revenues during its installation time. Once the technical issues and certification requirements
for a PED detection system have been resolved, flight crew training and enforcement policies must be developed to
address situations when potentially harmful PEDs are being used by passengers.
More recently several mobile phone manufacturers have demonstrated picocell systems to RTCA SC-202 and
EUROCAE WG-58 that could be considered to be mobile phone detection and mitigation systems. Such systems
have the benefit of being able to command the participating handsets to transmit at minimum power, thus possible
reducing EMI risk. Unfortunately, regulatory guidelines make it difficult to design such a system that will work
with all the mobile phone technologies used by passengers on a typical airplane flight (ie. CDMA, GSM, PCS, PDC,
3G, EDGE, etc.). In addition, it is nearly impossible to ensure that passenger mobile phones will not bypass the
onboard picocell and transmit (at maximum power output) to a terrestrial base station below.
One day, it is likely that some form of EMI detector will be commonly installed on board commercial airliners.
A simple cockpit indicator for one such concept is pictured in Figure 12. Detected signals that are not authorized for
the current flight phase, or violate airline policy, would be annunciated with a display in the yellow “Alert” range.
Detected signals that are likely to exceed allowable limits for safe operation of the aircraft would be annunciated
with a display in the red (“Alarm”) range. Additional information, such as the possible location of the offending
EMI source an a suggested course of action could be displayed in the “Message” field.
C. EMI Shielding Evaluation
The first reported measurements of electromagnetic shielding of commercial airplane apertures to prevent PED
coupling to aircraft radio systems was performed by Veda Incorporated, under contract to the FAA.34 A median
shielding effectiveness of 26 to 35 dB was reported when covering all port and starboard windows with aluminum
foil and tape. It was observed that shielding all the windows resulted in more variation of field levels inside the
passenger cabin (ie. “stronger modal structure”). Veda also experimented with using 2-inch foil tape to partially
cover aircraft windows. Over 10dB of additional shielding was reported when using only one strip of 2-inch tape.
Various combinations of aluminum tape and alternating window coverage were examined. The report did not reveal
the dependency of shielding effectiveness on particular RF bands however.
Figure 12: RF threat indicator (or status page on multifunction display)

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Additional shielding measurements were performed by NASA, EWI and United Airlines on B737-200 aircraft at
Victorville, CA in 200235. The merit of PED EMI mitigation by conductive sealing of door and exit seams was
evaluated by measuring airplane IPL with (and without) aluminum foil bonded along all window and door exit
seams along both sides of the airplane. See Figure 13, right. IPL measurement comparisons were performed for the
VHF1 communications, LOC and GPS aeronautical radio systems. Coupling from all passenger cabin window
locations to the VHF1 aeronautical communication system was reduced by about 5dB, and an even greater benefit,
up to 15dB, was obtained at the door and window exit locations when the seams were conductively sealed. For
LOC, coupling at most window locations was not significantly reduced. More than 10 dB of coupling reduction was
obtained at the doorways when the seams were conductively sealed. The merit of PED EMI mitigation by the
application of conductive window film was evaluated by measuring airplane IPL with (and without) film installed
on the first 12 windows on the starboard side of the airplane. See Figure 13, left. It was shown that coupling levels
may be reduced by more than 15 dB for GPS and more than 10 dB for TCAS by application of conductive window
film. These results demonstrate that the application of conductive films to aircraft windows may provide significant
reduction in PED EMI coupling to aircraft radio systems. This testing did not evaluate the level of protection
possible to aeronautical radio systems operating in the VHF and UHF radio frequency bands (ie. VHF Com, VHF
Omniranging, LOC, Glideslope) by applying conductive window film. It was recommended that more
comprehensive evaluations of conductive sealing of door seams combined with conductive window films be
performed for all aircraft radio systems in the future. These tests should consider aging issues and maintenance
strategies in the selection of materials and their installation.
During the course of some inspections of different types of aircraft doors, it was notices that B-777 doors appear
to be designed for improved electrical bonding to the aircraft structure. A photograph showing the change is shown
in Figure 5. Previous measurements by EWI and Delta airlines indicate that this change aircraft door seal design
may increase PED path loss through aircraft doors.
Figure 13: Top: Photo of airplane with door and exit seams electrically sealed with aluminum foil and tape.
Bottom: Photo of airplane with the first 12 window apertures electrically sealed with transparent conductive
film.

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22
The Aerospace Vehicle Systems Institute, part of Texas A&M University, currently has a project entitled
“Mitigating the impact of RF Emissions from PEDS Through Aircraft hardening”. The work is being performed
under an industry partnership, and is expected to provide valuable insight to RTCA SC-202.
V. The Future
A. Within the Next Decade
We are clearly in the midst of an unprecedented age of personal connectivity. Given the widespread adoption of
multi-band (and international band) mobile phones, wireless LANs & PAN enabled PDA’s, and keyless entry
systems, it is not unusual for a typical person to be carrying several transmitting devices at one time. The
introduction of UWB devices and RFID systems will surely lead to devices that are “location aware” within the next
several years. With improved authentication, encryption and security protocols, people will become increasingly
comfortable using their devices for purchases and exchange of personal information. It will soon become more
difficult for many people to even know that they are carrying transmitters. In fact, it is possible that many people
will become reluctant to turn their devices off at any time.
Several updated aeronautical radio services have been introduced over the past 10 years. Existing aeronautical
VHF Com infrastructure has been updated with VHF Datalink (VDL) capability, that allows digital controller-pilot
datalink (CPDLC) of text information, Wide Area Augmentation (WAAS) differential corrections of GPS
navigation data), and airplane broadcast of position and altitude information (Automatic Dependent Surveillance
Broadcast, ADS-B. ADS-B has been tested using aircraft universal access transceivers (UAT), SATCOM, and by
placing extended spectral content onto aircraft radio transponders. Many more details may be found in the FAA’s
Operational Evolution Plan (OEP).36
Perhaps one of the most exciting opportunities for the near future is the Airborne Internet. The idea of an
Airborne Internet began as a supporting technology for NASA's Small Aircraft Transportation System (SATS).37
The ultimate goal is to establish a robust communications channel between aircraft and various ground networks.
United Airlines has joined with AeroSat, Inc. (http://www.aerosat.com), Computer Networks & Software, Inc.
(http://www.cnsw.com), Project Management Enterprises, Inc. (http://www.pmei.com) and Mulkerin Associates,
Inc. (http://www.mulkerin.com) to form the Airborne Internet Consortium (http://www.airborneinternet.org/) The
Airborne Internet Consortium promises to make aircraft easier to fly with more situational awareness, safety, and
security, by utilizing Internet protocols and services in flight. These new services will also increase the productivity
of passengers because the growth in connectivity will allow people in transit to use otherwise unproductive time.
This expanding use of RF spectrum for personal connectivity, combined with new and unforeseen applications
of Airborne Internet and expanding aeronautical radio services makes it likely that more EMI interactions will occur.
Figure 15 shows an overview of PED and CNS technologies of today and tomorrow. The middle area identifies the
level of published data addressing their potential interactions. Though the efforts of the RTCA, FAA, NASA,
airlines, avionics manufacturers, aircraft manufacturers and others, significant information is available to assess the
Figure 14: Left: B747-400 Door contact point. Right: B777 door contact point. Note: each contact point on the
B777 door has a ground strap.

American Institute of Aeronautics and Astronautics
23
potential interaction between today’s PEDs and today’s CNS systems. Much work remains to ensure that these
exciting new applications do not lead to unforeseen consequences.
Mobile Phones
(AMPS, IS-95 CDMA, GSM, 3G)
IEEE 802.11a, b, g
Bluetooth
FRS/GMRS Radios
Today
Tomorrow
PED Technologies CNS Technologies
Mobile Phones- (>3G, 4G)
UWB
(Wireless USB, IEEE 802.15.3)
Software defined Radio
Cognitive Radio
MIMO Systems
??
VHF Com DME
VOR ATC
LOC TCAS
GS GPS L1
SATCOM
VHF Com+ (VDL: ADS-B, LAAS, CPDLC,
NEXCOM, TIS-B)
UAT (ADS-B, FIS-B)
1090 MHz Extended Squitter (ADS-B)
GPS L5, L2
SATCOM+ (ADS-B, Swift 64,
other INMARSAT, ?)
Airborne Internet
(Connexion, AeroSat, Airfone, AirCell, FAM Com,
JetConnect, Sirius, XM, EFB, IRIDIUM, etc.)
?
?
Some Data
Published
?
Mobile Phones
(AMPS, IS-95 CDMA, GSM, 3G)
IEEE 802.11a, b, g
Bluetooth
FRS/GMRS Radios
Today
Tomorrow
PED Technologies CNS Technologies
Mobile Phones- (>3G, 4G)
UWB
(Wireless USB, IEEE 802.15.3)
Software defined Radio
Cognitive Radio
MIMO Systems
??
VHF Com DME
VOR ATC
LOC TCAS
GS GPS L1
SATCOM
VHF Com+ (VDL: ADS-B, LAAS, CPDLC,
NEXCOM, TIS-B)
UAT (ADS-B, FIS-B)
1090 MHz Extended Squitter (ADS-B)
GPS L5, L2
SATCOM+ (ADS-B, Swift 64,
other INMARSAT, ?)
Airborne Internet
(Connexion, AeroSat, Airfone, AirCell, FAM Com,
JetConnect, Sirius, XM, EFB, IRIDIUM, etc.)
?
?
Some Data
Published
?
B. Within the Next Few Decades
With the increasing demand for more and more wireless bandwidth, RF spectrum will become increasingly
scarce. In the near term, this is already leading to more efficient waveform technologies being used in existing RF
spectrum allocations (ie. closer channel spacing, spread spectrum technologies, frequency reuse, etc.). Today,
software defined radio (SDR) systems are being evaluated that can operate bandwidths of hundreds of Megahertz.
Current research utilizing channel sensing, broadband monitoring, adaptive transmit power and adaptive bandwidth
will lead to systems that can readily adapt to their RF environment. Furthermore, as technology progresses to allow
radio systems to become aware of their location (ie. RFID, GPS, etc.), it will become possible for future T-PEDs to
adjust their frequency use and power levels to conform to local and international RF spectrum restrictions.
An overview of this expected transformation was published in the January 2005 Joint E3 Bulletin.38 In the
Bulletin, it is stated that “a fundamental transformation is required in the way the DoD obtains and utilizes its
spectrum resources if it is to effectively employ emerging technologies such as smart antennas, ultra-wideband
(UWB) systems, software-defined radios (SDRs), and adaptive waveforms.” To support this transformation, the
DOD has established the Emerging Spectrum Technologies (EST) Program to examine how spectrum is accessed
and utilized by the DoD in the future. An excellent chart from this reference is provided in Figure 16.
Figure 15: Overview of PED and CNS technologies of today and tomorrow, showing the level of published
data addressing their potential interactions.

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24
VI. Conclusions and Recommendations
Aeronautical CNS, ATM and IFE are in the midst of a transformational era. Surely, broad bandwidth, low cost
datalinks will find their way onto passenger airplanes. Air carriers, passengers and governments will find creative
and ingenious ways to utilize these technologies to improve the safety, economy, efficiency and enjoyment of air
travel. We are also in the midst of an exciting age of personal wireless connectivity. As air travelers continue to
become more comfortable with existing and emerging wireless transmitters, it will becoming increasingly difficult
for flight attendants and passengers to discern whether today's highly integrated and multi-function devices are
designed to transmit or not. Observations suggest that passengers are increasingly likely to knowingly operate
unauthorized transmitters while on board aircraft.
The interplay between evolving CNS, ATM, IFE, and passenger wireless connectivity will continue to evolve in
ways that will certainly impact the safety and security of air travel. It will be a continuing challenge to understand
safety and security problems as/before they develop, design solutions to those problems, and effect policy and
procedural changes for airlines and governments.
A. Understanding the Problem
1. PED Spurious Radiated Emissions
Through the efforts of RTCA committees, NASA, the FAA and others, a significant body of PED spurious
radiated emission data has been published. A standard set of procedures for measuring spurious radiated emissions
in aircraft navigation radio-frequency bands from common and emerging wireless transmitters has been developed.
While these efforts quantify the threat from many existing PEDs, they do not bound the potential EMI threat from
newly emerging T-PEDs, or modified or damaged devices. Radiated emission characteristics of future T-PEDs will
Figure 16: U. S. Department of Defense perspective on the transformation of RF spectrum operations

American Institute of Aeronautics and Astronautics
25
also need to be determined. In fact, new radiated emission measurement processes should be expanded to account
for signal characteristics other than peak amplitude (i.e., modulation types and parameters, duty cycle, bandwidth,
etc.), for more accurately quantifying the potential for EMI to aircraft communication and navigation radios. It may
be possible to build database to establish confidence in signal compatibility for certain product types, and identify
particular products that threaten aircraft signals. Finally, it is important to study the potential for devices transmitting
on different frequencies, and possibly regulated by different national standards, to generate intermodulation products
in aircraft navigation radio-frequency bands. While FCC and CISPR emissions standards must be met for products
sold in the United States and Europe, they are not intended, and are therefore inadequate, for protecting aircraft
spectrum from passenger generated EMI.
2. Aircraft Coupling Data
Extensive front-door IPL data has been collected by the RTCA, NASA, EWI, Delta Airlines, United Airlines,
Sky West Airlines, Air Wisconsin, Airbus and others. Unfortunately, all this data is not compiled in a standard
format in a single comprehensive reference. Many airplane types have never been subject to such measurements.
Also, more effort needs to be devoted to statistical analysis of IPL probability distributions based upon seat location,
airplane type, and airplane version.
Some analysis of back-door IPL analysis was documented in RTCA/DO-233 for non-transmitting PEDs. This
work was essentially republished in EUROCAE/ED-118. It is still unknown whether common mobile phones and
FRS/GMRS radios, placed inches from aircraft wiring, may couple enough power into aircraft systems to cause EMI
anomalies.
3. Aeronautical Radio Receiver Susceptibility
While aeronautical radio receiver sensitivity thresholds are well established, their susceptibility to different types
of EMI signals is not understood. A standardized susceptibility measurement process for aircraft navigation radios
needs to be developed. Multiple types of aircraft navigation radios should be characterized to establish database of
typical susceptibility to EMI from present and future PEDs. Different susceptibility threshold requirements for
navigation radios, based upon operational requirements (ie. minimum service levels and IFR conditions) should be
developed.
4. Operational Insight
How pilots respond to various types of EMI events is largely unknown. In some cases, serious degradation of
CNS data may be corrected by changing to a different channel, or switching the aircraft radio to a different antenna.
To date, no commercial pilot training program exists to inform pilots about how to recognize EMI events and
minimize their impact on the safely flying the airplane. EMI events that affect the interaction between flight crews
and flight controllers in the overall CNS/ATM infrastructure need to be considered. Operational Insight becomes
much more critical if an aircraft is subject to an EMI attack.
B. Designing Solutions
Due to the global interplay between CNS, ATM and new wireless technology development, it is especially
important for government regulatory agencies and research organizations to collaborate extensively with airlines,
airplane manufacturers, avionics manufacturers and wireless product manufacturers and standards organizations to
develop solutions to current and future EMI problems. These EMI problems have both safety and security
implications.
Table 1 shows a perspective on the new dynamics, concerns and solutions from the author’s perspective.

American Institute of Aeronautics and Astronautics
26
Table 1: EME and Aircraft: Dynamics, Concerns & Solutions
•Vulnerability Assessment of CNS/ATM
to HIRF Kits & Plans and COTS Equip.
•Collaboration with DHS, DOD
•Secure CNS, SASIF
•On-Board Spectrum Monitoring
•Crew Training to Identify & Mitigate
EMI attacks
•Commercial Airplane Design & Test
Incorporates DOD EME Requirements
•EMC Testing of New PED-
CNS/ATM technologies
•Collaboration with FCC, ITU, etc.
•Secure CNS, SASIF
•On-Board Spectrum Monitoring
•Crew Training to Identify & Mitigate
EMI events
•Airplane Design for EMI Control
(VHM, CUPR, AVSI, RTCA, etc.)
•Neutron Particle Testing of
Avionics to identify
susceptibility
•Avionics Design for
Control of Upsets (VHM,
CUPR)
•EMI techniques will be used to Exploit
CNS/ATM Infrastructure: COTs
Equipment; HIRF Kits & Plans
•EMI Attack Option is “Sensational”
-Effective: Economic Impact, Media
Coverage, Public Confidence
-Anonymous: Difficult to ID Source
-Repeatable: Just add Electricity
•EMI Events will Impact Aircrew
Operations More Frequently
•EMI Events are Difficult to Identify,
Repeat and Resolve
•Existing Certification and
modeling tools are not
adequate
•CNS/ATM Increasingly Dependent
Upon Radio Technologies
•HIRF weapon kits & plans increasingly
available to the public
•Publicized Use of HIRF & EMP
Weapons by Military/Government
•CNS/ATM Increasingly Dependent
Upon Radio Technologies
•PED Technology: Ubiquitous
-RFID, UWB, IPV6, IEEE802.???
•Spectrum Policy Evolution
-Spectrum on Demand
-Wireless Global Information Grid
-International Policy Variation
•Application of Composite
Materials to Airplanes
•High Altitude Flight
•UAV’s
Man-Made MaliciousMan-Made InadvertentNatural
•Vulnerability Assessment of CNS/ATM
to HIRF Kits & Plans and COTS Equip.
•Collaboration with DHS, DOD
•Secure CNS, SASIF
•On-Board Spectrum Monitoring
•Crew Training to Identify & Mitigate
EMI attacks
•Commercial Airplane Design & Test
Incorporates DOD EME Requirements
•EMC Testing of New PED-
CNS/ATM technologies
•Collaboration with FCC, ITU, etc.
•Secure CNS, SASIF
•On-Board Spectrum Monitoring
•Crew Training to Identify & Mitigate
EMI events
•Airplane Design for EMI Control
(VHM, CUPR, AVSI, RTCA, etc.)
•Neutron Particle Testing of
Avionics to identify
susceptibility
•Avionics Design for
Control of Upsets (VHM,
CUPR)
•EMI techniques will be used to Exploit
CNS/ATM Infrastructure: COTs
Equipment; HIRF Kits & Plans
•EMI Attack Option is “Sensational”
-Effective: Economic Impact, Media
Coverage, Public Confidence
-Anonymous: Difficult to ID Source
-Repeatable: Just add Electricity
•EMI Events will Impact Aircrew
Operations More Frequently
•EMI Events are Difficult to Identify,
Repeat and Resolve
•Existing Certification and
modeling tools are not
adequate
•CNS/ATM Increasingly Dependent
Upon Radio Technologies
•HIRF weapon kits & plans increasingly
available to the public
•Publicized Use of HIRF & EMP
Weapons by Military/Government
•CNS/ATM Increasingly Dependent
Upon Radio Technologies
•PED Technology: Ubiquitous
-RFID, UWB, IPV6, IEEE802.???
•Spectrum Policy Evolution
-Spectrum on Demand
-Wireless Global Information Grid
-International Policy Variation
•Application of Composite
Materials to Airplanes
•High Altitude Flight
•UAV’s
Man-Made MaliciousMan-Made InadvertentNatural
New DynamicsConcernsSolutions “Risky Behavior”“Consequences”
Acknowledgments
The majority of content in paper is a summary of works provided in the reference section. As such, the author
acknowledges the contributions of the NASA LaRC HIRF Laboratory Team: Reuben A. Williams, Truong X.
Nguyen, Sandra V. Koppen, Theresa Salud, George N. Szatkowski, Max Williams, and John H. Beggs; Delta
Airlines: Kent Horton, Brian Eppic, Mitch Huffman, Harrison White; and the UWB Direct Effects Team: Gerald L.
Fuller, Warren L. Martin, Timothy W. Shaver, John Zimmerman, William E. Larsen and James H. Hollansworth:
the FAA Certification Office and Tech Center: Dave Walen, John Dimtroff and Anthony Wilson; and those who
have supported the RTCA Special Committees on PEDs. NASA’s contributions to this work are a direct result of
funding from NASA’s Aviation Safety and Security Program, with help from the FAA and the NASA HQ Office of
Space Flight.
Note
The use of trademarks or names of manufacturers in this paper is for accurate reporting and does not constitute
an official endorsement, either expressed or implied, of such products or manufacturers by the National
Aeronautics and Space Administration.
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