Don Hudson and PBL on the ITU’s proposal for real-time flight data transmission

The International Telecommunications Union has been conducting its four-yearly meeting. Its president has apparently promised everyone to make possible the real-time transmission of flight data from commercial transport aircraft in flight. This has been supported by the Malaysian delegate. All according to this news report: MH370: ITU Commits to Integrate Flight Data Recorders with Big Data and Cloud, writes Vineeta Shetty from Dubai

Captain Don Hudson is a valued colleague for well over a decade. He has some 20,000 or so flying hours, has flown a variety of transports, including Lockheed L1011, Airbus A320 and varieties of A330 and A340 machines and is an active professional pilot although formally retired from scheduled airline flying. While with Air Canada he contributed significantly to the development of the airline’s safety-management and flight-quality systems while he was a captain on intercontinental flights.

Don points out, as have others, that the technology exists to do what the ITU proposes. However, he finds the proposal problematic, as do I, and economically and from a safety point of view barely justified, if at all.

It almost goes without saying that people expert in the standardisation of telecommunications are not necessarily expert with the human and organisational factors involved with aviation safety programs. Don is expert. I recommend that ITU delegates read what he has to say below. Some comments of mine follow.

Captain Don Hudson: Response to the ITU’s proposal for real-time flight data transmission

Some important issues have not been addressed in the ITU’s suggestions.

Aside from any commercial priorities and processing/storage/retrieval issues regarding DFDR and CVR data, a number of important issues are not addressed in this announcement.

I suspect that each individual country would “own” their carriers’ data. Given the difficulties with establishing even a “local” distributed archive of flight data within one country, even purely for safety purposes and with limited access, I doubt that such a flight-data archive will be hosted by a world body anytime soon. Within such a proposed arrangement lie a number of serious impediments to international negotiation, not the least of which is the potential for legal prosecution of one country’s flight crews by other countries. Such data could be a legal goldmine for various interested parties and that is not what flight data recorders and CVRs are for. Their purpose is expressly for flight safety.

I submit that such a suggestion to stream flight (and CVR?!) data would be an initiative to solve the wrong problem – the one of disappearance, of which there have been only two very recent cases among millions of flights and billions of passengers, all carried under a safety record that is enviable by any standards.

The main problem that many are trying to come to grips with is certainly real. We needed to know what occurred to AF447 and the results of that knowledge have materially changed the industry in many, many ways. We need to know what happened on board, and to, MH370.

What makes more sense, in place of a wholesale sending of hour-by-hour flight data from every flight at all times, is a monitoring function something along the lines of the work Flight Data Monitoring people perform on a regular, routine basis, but do so on-board the aircraft, using a set of sub-routines which examine changes in aircraft and aircraft system behaviours to assess risk on a real-time basis.

Flight data analysts look for differences-from-normal – a rapid change in steady states or a gradual change towards specified boundaries, without return to normal within expected durations. It is possible to define a set of normal behaviours from which such differences can trigger a higher rate of capture of key parameters. This approach is already in use on the B787 for specific system failures. A satellite transmission streams the data set until either the differences no longer exist or end-of-flight.

Flight data quantity from aircraft such as the B777 is in the neighbourhood of 3 – 4 MB per flight hour. Most events prior to an accident and relevant to that accident are moments to minutes in duration.

The two industry events which have triggered the ITU interest were a rapid departure from cruise altitude & cruise Mach (AF447) and MH370, with which a sudden change in aircraft routing concurred with a loss in normal air-ground routine transmission by automated equipment, (transponder, ADS-B). Both these events lasted moments and would be events that would initiate data-capture and transmission in my proposed scenario. In the MH370 case the transmission would remain active until end-of-flight. If the AF447 aircraft had been recovered from the stall and had made destination, the data would still be in place off-aircraft. Loss of satellite signal occurred on AF447 but the problem would not have prevented an initial data stream (See the BEA Interim Report No. 2 on AF447, p39).

The flight phases defined as “critical” by AF447 and MH370 are from the top-of-climb to the top-of-descent phases, in other words, the cruise phase. From the takeoff phase through the climb to cruise altitude and the descent/approach and landing, no such need for this kind of system exists, because any accident site is going to be within about 150nm or about one-half-hour’s flight time from departure and arrival.

An “on-condition” data transmission would be more practical and cheaper than full-time transmission of flight data, which would bring the notions expressed by many regarding these issues a bit closer to implementation.

Besides flight data, there is cockpit voice recording (CVR). The data issues with CVR transmission require a parallel and separate examination.

Don Hudson

[End of Hudson’s Essay]

PBL Comments on Hudson

Concerning the ITU’s statement, I fail to see what either big-data analysis or cloud computing have to do with real-time data transmission from aircraft in flight. I suspect an infection by buzzword.

The ITU is suspected by many people concerned with the Internet, and certainly by most in the IETF, to be a political body more interested in control than in enabling technology. This current announcement does seem opportunistic, and, as one can see by connection to “cloud” and “big data”, some of its senior officers apparently don’t really understand the technology which they want to regulate.

There are further questions which Don does not address above.

Who is going to pay for it, and will the expense be justified? Likely will the satellite companies gleefully support the proposal (see the article’s comment on Inmarsat), given that through it they would be rolling in cash. But where shall that cash come from in a boom-and-bust industry such as airlines? Likely from the passengers through an increase in fares. So one would be asking passengers to pay for a service on their flight for which the rest of the world would only benefit if the flight crashed and said passengers died. That seems to be stretching everyday altruism to its limits.

As Don points out, such a proposal would have helped in precisely two cases in five years. But Air France was found, at a cost according to this Newy York Times article of €115m, and it currently looks as if MH 370 will also be found, so someone will be able to estimate the cost of that. A cost-benefit analysis (CBA) is thus possible, though I guess there would be lengthy argument over the components of the calculations. With a CBA a decision on implementation would come down to attempting to reduce, respectively to raise, the cash paid to satellite companies, and that seems to me to be a commercial issue and not one which governments would or should care to resolve in the absence of demonstrated need. I doubt governments would want to end up paying out of taxes. Surely, any individual government would prefer to put such resources into improving its surveillance capability, and expect to use those covertly in the very rare cases such as MH 370?

To the main point. How would real-time data transmission kit have helped in the search for MH 370?

Likely it would not have helped at all, if the current hypothesis of deliberate human action is validated. Such a system, like the transponder and ADS-B, can be turned off. For reasons of basic electrical safety, a discipline established over 100 years ago, you have to be able to turn off any given electrical circuit in flight. You can make it easier or harder, but no certifiable design can allow that it be prevented. Thus no such system is resilient against intentional human action.


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