Air Traffic Control - Science topic

Thanks a lot.

ATC Towers are critical for surface movement and take off- landing clearances of the arrival and departing aircraft. So it's construction is with this basic premise of giving it maximum visibility. You can go through these videos for your better orientation.

Kalina Tcholakova

I think reasons not to do a meta-analysis revolve around intolerable differences between studies. Ones that may be mentioned in the literature of your field and proved to make a difference in the outcome. For example, in clinical research different doses of a drug can be a problem, specially if the difference was established in published articles.

To manage these discrepancies, you can do a "subgroup analysis" which makes a separate MA for each set of circumstances and compare each group with certain differences. Or you can do a sensitivity analysis, which involves removing studies that are substantially different (by some defined factor) and see whether removing them makes changes on the pooled estimate. However, it doesn't completely solve the problem, sometimes it's just not a good idea to compare studies using a meta-analysis. If so, try to report results of studies narratively, many systematic reviews are published without MAs. Good luck!

Dear Charles,

Thank you very much for your message and for the valuable documents. I am also very actively involved in this line of research. A recent paper on GNSS performance threats and augmentation strategies in aviation was recently published in JPAS (for convenience, the link is provided below):

In addition to addressing GNSS issues, it would be nice working together and investigating the feasibility of specific safety features that could be included in the ADS-B data-link as well.

https://confcats_isif.s3.amazonaws.com/web-files/journals/entries/308_0_art_11_27647.pdf - article on Asynchronous Track-To-Track Fusion, though I have not used this article.

What is the difference between the periods of the two radars? Does the prediction of one track sampling time to the other one help, to get to a common sampling time help?

Have you solved the association problem?

For synchronous tracks, I've got good results using the association and fusion equations in article "Multisensor Track-to-Track Association for Tracks with Dependent Errors" - Huimin Chen and Bar-Shalom.

Look for prof. Bar-Shalom articles in the domain, he has some great ones.

Hello. Fusion of asynchronous radar tracks requires prediction of all track estimates/covariances to the most recent measurement epoch. You wish to calculate the posterior PDF of the target state (assuming no data association problems!) p(x(k) | Y1^k, ... , YN^k ) where Yi^k is the set of measurements from radar i up to time k. You can approximate this PDF using the formulae you provide but you have made a number of assumptions, the most important of which are: (1) the measurements sequences are actually from the target with state x(k); (2) the process noise for each filter is independent. In practice, both these assumptions are violated. There is a fairly simple way to deal wtih (2) on the common process noise. This is covered in Bar-Shalom and Fortmann's 1988 monograph (in the appendix, I think). Your problem is a bit more complicated due to multiple motion models, but that should not deter you! IMM type approximations will help. Good luck. Please upvote if you like this answer.

Yes,there are already lot of articles on it.

Dear Giacomo,

We recently explored the effect of outcome bias on reporting intentions. Whilst our participants were primarily training to work in aviation management, I think what we found might be relevant to ATC too. Gilbey, A., Tani, K., & Tsui, WHK. (2016). Outcome Knowledge and Under-reporting of Safety Concerns in Aviation. Applied Cognitive Psychology. 30(2), 141-151 (If this may be of interest, I can send you a copy if you don't have easy access).

It might be a fascinating topic to research; our study might even work as a template to do so,

Regards,  Andrew

Hello. This is an interesting question. There are a couple of Viterbi/EM techniques that you may wish to try. They are compared with IMM in the paper below. You may get some more ideas from the survey paper I did (it was "gazumped" by Li's paper, despite being done earlier). The title is "A Survey of Manoeuvring Target Tracking Methods" but I can't find the link right now..

Hi Karthik, the website attached has a detailed guide on the process of decoding ADS-B packets. To generate your own packets it is simply the same process in reverse. I hope this is helpful.

Hello Gerald, Ulli, Volker,

There quite a few nice examples I'm aware of where accretionary lapilli were sampled soon after fallout. One is the 2002 study by Bonadonna et al. on the 1995-1999 eruption at Montserrat (Geol. Soc. London Memoirs). Another is the 2009 eruption of Redoubt, Alaska, described by Kristi Wallace et al. in JVGR, 2013. The latter samples provided the basis of my study of 'volcanic hail' using radar observations and plume modeling with ATHAM in Nature Communications. As suggested by Gerald, these samples were indeed frozen upon landing, though that's not too surprising for an Alaskan eruption. It is clear from lab experiments that neither ice nor salt precipitates are required to grow aggregates >1cm diameter. I do not think aggregates need to undergo freezing, however, it does seem to be very common and does affect their growth rates and internal structure. 

There are also some gorgeous, layered accretionary lapilli from the 18 May 1980 eruption of Mount St. Helens, which have been archived for the past 35 years. I've recently thin-sectioned these samples and am currently working on comparing their internal structures to the eruptive stratigraphy and photographic record of the eruption dynamics. Hopefully I'll be presenting this work at the Cities on Volcanoes meeting in Chile this year. Ulli and I were talking about organizing a workshop on ash aggregation there if there's enough interest. 

All the best

Alexa

@Robert_Hutton - I am quite familiar with Klein's work on expert behavior.  The problem that we are dealing with is that our controllers are experts at what they are doing.    Controllers recognize the solution, but to be able to do so, they need to be able to perceive the situation.  At the moment we are tinkering with the basic building blocks that controllers use to build their model of that situation.  I fully agree with you that controllers are not thinking in chunks of characters, or even chunks of aircraft, but not knowing what the impact of changing the basic building blocks puts them at risk to no longer being able to use their expertise.  Compare it to changing the layout of a chessboard for chess masters or changing the content of the fields in a data block with Chinese characters.

What do we really know about experts that have looked at the display format for several decades?  How many aircraft can they track?  How much can they see in the periphery? I have worked with controllers for 20 years and I still don't have the answers, but I am trying to find if others have looked at similar issues before.

Psycholinguist Rainer Dietrich of the Humboldt University (Berlin) has worked on the language of ATC. You might find references to corpora in his work.

Hello Gerard,

 In your extensive analysis you did not include the fact that the Greek population is well educated and aware of the natural dangers that hit all too common for millennia. Although the country is short of money, many research projects are funded from EE and elsewhere, so there is not a big increase of risks since 2008.  You see some of the projects mentioned above.

For example, the Greek people were well aware of tsunamis before Dec. 2004, unlike most of the rest of the world. I think Greek people are better prepared than those in Canada by comparison. In the last 10 years or so the federal funding for anything to do with the environment including research at universities in Canada has been severely CUT to avoid people get the facts on weather, natural disasters, etc. The reason is the government has been extremely pro-fossil fuel with a “forget the environment” attitude (also was the only country to officially return its signature from the Kyoto Protocol).  The result is a big problem for preparedness in a developed country and a worry for those trying to educate the public/schools, etc

Some suggestions:

CORREIA, T.C.V.D. ; SOARES DE MELLO, J.C.C.B. . Avaliação da eficiência das companhias aéreas brasileiras com o modelo Fuzzy-DEA. Relatórios de Pesquisa em Engenharia de Produção da UFF, v. 8, p. 5, 2008.

BARROS, T.D ; RAMOS, T.G. ; SOARES DE MELLO, J.C.C.B. . Avaliação dos atrasos em transporte aéreo com um modelo de Análise Envoltória de Dados. Relatórios de Pesquisa em Engenharia de Produção da UFF, v. 8, p. 6, 2008.

Something else to consider is that, if you're using precip mode as a proxy for precipitation being present in the radar scan, this isn't always perfect. Precipitation (often isolated) may still be present in clear air mode, which can affect any calculations of bird density. Likewise, radars can be in precip mode but with no precipitation around. 

As an Air Traffic Controller, I like my instructions to be understood by the pilots. If both of us are going to follow different languages as a medium of radio telephony, then imagine the confusion! Already we are facing the problem of phonetics and different pronunciation among all the stake holders in aviation like pilots,ATCOs and ground crew.The use of non-standard procedures and phraseology can cause

misunderstanding. Incidents and accidents have occurred in which a contributing

factor has been the misunderstanding caused by the use of non-standard

phraseology.

The worst accident in aviation history i.e.,Tenerife collision between two B747s on 27/03/1977 was due to non standard R/T only. So standard and uniform R/T is a must for safe operations. Language was a part of important factor in many accidents like Milan Linate airport MD10 and a Cessna. etc

Follow the link to know about the english tests satisfying the ICAO SARPs for Language proficiency requirements.

Regarding the air traffic through out the world check ACI (www.aci.aero) or IATA (www.iata.org). They are publishing the air statistics regularly in their sites.

If you feel I may be of further helps,please inform me.

Regards and best wishes.

Find attached some articles I saw on the internet.

There are several books on Kalman filtering and integrated navigation that would give you the answers, at least in part--This book by Paul Groves is the state of the art:

and the book by Britting is the classic on inertial integration:

The Kalman filter is a state observer (or Luenberger observer) or estimator that minimizes the variance of the state estimate obtained from measurements. It is able to do so in real time because it is implemented recursively--it doesn't take very much of computing or memory in each step--relative to what a batch optimization method would take for example.

Thus, the Kalman filter simply takes the various measurements in a suitable coordinate frame as output equations (e.g., y(k)=Cx(k)+D1u(k) +v) with measurement noise v, and estimates the state of the system x(k+1)=Ax(k)+B1u(k)+B2w(k) with state x and process noise w. This is usually done in the body frame of the aircraft, and then transformed suitably to LLH (latitude longitude, height), NEH (north, east, height with some local origin), or ECEF (earth centered earth fixed--usually used in GPS and satellites)  coordinates to aid the flight control and flight management systems. The state of the aircraft, or most any vehicle, is typically its 3 components each of position, velocity, attitude, and angular velocity.

The execution time for a Kalman filter on a commercial aircraft was under 5 milliseconds even in the 1990s. It assumes that the governing dynamics of the body are linear differential or difference equations, and that the measurement noise and process noise are normally distributed.

These are strong assumptions, and certainly not true for an aircraft, whose dynamics are nonlinear--as with any rigid body governed by the Euler equations. However, most aircraft operate in the regime of linear dynamics and linear aerodynamics, i.e., they mostly fly at small angles of attack in ascent or descent, and mostly straight and level. While measurement noise is normally distributed in many cases, especially when produced by circuitry (Johnson noise, shot noise and flicker), process noise is seldom well characterized, and depends upon the context, and the aspects of dynamics we choose to ignore. However, when when high sampling frequencies are available for measurements, vehicle dynamics can be approximated by simpler models to great effect.

At design stages, ARP4754a and ARP4761 are referred, but purely an industry practice. The tools used are FTA or Markov Chains to derive specified hazard probability.

You may want to reach out to Doug Baart and Albert Schwartz at the FAA. They use models like RAMS Plus and Agentfly all the time.