Radio transmission of FDR and CVR information?

Hi everyone,

Up until now, I have always posted questions pertaining just to flight simulation. But now that we have reached the third anniversary of the missing Malaysia Airlines Flight 370, I wanted to pose this question. I know that many of you are aviation experts, unlike me who know only the scantiest amount about real-world aviation (do I even know that much?). The only thing that I know comes from my use and study of FSX Steam Edition — although for sure this has been a very instructive piece of software.

So, here is my question. This is not my thought, but I have heard this suggestion posed regarding the two “black boxes” for the flight data recorder and the cockpit voice recorder. The suggestion has been that the information contained in those physical structures instead be continually transmitted via radio to air traffic control. Once the flight arrives safely at its destination, then this information could be deleted.

As I understand it, the objection to such a procedure would be the cost involved in transmitting and temporarily storing the data. Countering that objection, however, one could note that the cost involved in locating the physical black boxes in difficult terrain or under the water would at least negate the cost involved in radio transmission. In the end, it might be less expensive to transmit the data over the radio waves.

The case of the Malaysia Airlines flight is an extreme example, for sure, but other cases involving difficult and expensive searches have also arisen. Furthermore, if the data were transmitted, then the aviation community and the public could rest content knowing that the data could definitely be obtained if necessary.

So, does this idea make any sense or not?

Thank you.

Stanley

The expense (and difficulty) isn't due to installing a radio transmitter on the aircraft, so much as how do you get the signal to a place where it can be stored? Radio transmissions are typically short range (line of sight, for antennas that fit well on aircraft). So that Malaysian flight was likely out of range of normal communications when it went down (at least from what I've read).

So where do you put receiving stations (hundreds, perhaps thousands of them), to accommodate the thousands of airliners around, or how do you get satellites (it would take a few) with sufficient capacity (then the various ground stations they would need) up there, and who bears the expense and who controls them, and who makes the regulations (getting all countries to do this?) to force the airlines to do it?

So you get into politics and huge expense and technical difficulty all in one package. Incidentally, that huge expense for searching for that Malaysian plane is a drop in the bucket compared to what would be needed for your suggestion, plus it's rarely needed, so a humongous expense to be very rarely used, along with the politics (who does what) and technical problems (lots of them).

Does this help?

Inmarsat is offering free global flight tracking for commercial aircraft. It includes the option of streaming voice and flight data based on defined trigger events, such as unapproved deviations.

http://www.inmarsat.com/news/inmarsat-provide-free-global-airline-tracking-service/

With more and more airliners taking routes over more remote areas of the planet, this is going to be more important as time goes on.

Hi everyone,

Now I am confused. Following the cogent arguments put forth by lnuss, it seemed that tracking aircraft flights by radio was impractical. But according to what loki writes, this very thing is starting to be done.

Stanley

Hmmm... how will they finance this, if it's free? And I'm not sure how extensive the Inmarsat network is, or whether they can handle the bandwidth. You're talking a commercial service, so someone will be paying somewhere, but I'd expect this would be a gradual ramp up.

Note, too, that this is a proposal, mentioned in a press release (not a news item as such), and is not an existing service:

They also say:

So this wouldn't be a constant update, but only triggered by "certain defined trigger events" (obviously an inflight explosion wouldn't have time to transmit). So it's only a (relatively) crude substitute for what Stanley asked about, though it might be a start. If they are only talking about location tracking, that's relatively little data, compared to Stanley's question of the contents of two black boxes -- a huge difference, actually.

Addendum: I notice that Wikipedia has this to say about Inmarsat Ltd (a British company) as related to Malaysian Flight 370:

So there apparently is an existing satellite network that can provide at least some form of communications from airliners, but what its capacity is will be a question if this proposal goes through.

But, as far as continuous transmission from all airliners, my comments still stand. They list the factors involved, even if someone is already doing a tiny piece of this, and bandwidth is still a question, too.

Hope this clears your confusion, Stanley.

Yes, there is a ways to go yet to do everything Stanley asked, however, technology has been steadily improving and satellite coverage is getting better all the time. See the link below for Inmarsat's coverage.

http://www.inmarsat.com/about-us/our-satellites/our-coverage/

Streaming the complete contents of the black boxes may be overkill in the vast majority of cases, so restricting it to a subset of what the flight data recorder tracks may be good enough. This would cut down on the bandwidth, especially if you don't have to worry about audio. The larger issue is tracking and locating aircraft anywhere in the world. Having some flight data, and an accurate location at all times would help get SAR to the crash site where ever it was.

One of the other proposals that has come up again after MH370 is the battery life of the transmitters in the black boxes. Also having an emergency buoy that was released on impact with water, or released if submerged, would greatly help. If an accurate location was provided through satellite coverage and a buoy, and the black box battery life increased from 30 to 90 days, we would at least be able to find missing aircraft like MH370 without having to comb half an ocean.

Forgot to add that more and more airlines are offering in flight internet. This would require far bandwidth than uploading the data from the flight recorder.

It looks like tracking ADS-B data aircraft are now broadcasting is also possible to potentially provide the location of all aircraft around the world.

https://spaceflightnow.com/2015/05/07/space-based-airplane-tracking-demonstrated-by-esa-satellite/

Hi lnuss,

Yes, this does clarify things quite a bit.

I thank both of you for weighing in on this. It was very instructive.

Stanley

Hmmm... how will they finance this, if it's free? And I'm not sure how extensive the Inmarsat network is, or whether they can handle the bandwidth. You're talking a commercial service, so someone will be paying somewhere, but I'd expect this would be a gradual ramp up.

This news release may provide a hint as to how the service will be paid for.

https://www.airnewzealand.co.nz/press-release-2016-air-new-zealand-to-introduce-inflight-wifi

The airline and passengers could pay for the in-flight internet access and Inmarsat then throws in the flight tracking and flight data uploading for free.

but I read that all or most military aircraft in the U.S have a buoy for their black boxes.

I don't know about all the US Military aircraft, but I do know that on the F/A-18, C model and up, they implemented a rather interesting "black-box retrieval" set-up. The FDR and CVR are a single unit, on the back end of the aircraft, between the vertical stabilizers. It's mounted in the fuselage, just under the skin, between the engine nacelles. If/when the bird impacts anything, water, earth, ship's round-down, whatever, with enough force to be considered a crash, or the pilot has ejected and then there is such an impact, it ejects it's self from the aircraft with a fair amount of force, and glides a short distance away, clearing the crash area. It's mounting is a small, lifting body shape, thus permitting the glide. It also floats, a huge advantage in Navy birds :)

There's your "bouy", at least on the F/A-18. As far as I know, they are working on implementing this sort of thing on ALL the Navy aircraft. COD's, fighters, sub-chasers, you name it.

I'm not sure about helicopters. There's the problem of the main rotor interfering, just as with ejection seats for the crew. I'll see what I can dig up.

As to the "final" record of data from the FDR/CVR: with data compression, and burst transmission set-ups, the bandwidth and data storage isn't really a huge problem. But that's just for the final data from the two, not a continuous data read. The method would still dramatically reduce the bandwidth required for any given aircraft. Multiply that by the number of aircraft in the air at any given time nowadays, however, and you again start running into problems. Bandwidth, storage room someplace, frequency assignments, etc. Add in the politics for forcing all countries to adopt any sort of method, and the problems of such things expands exponentially.

There's my 2 pennies worth...

Pat☺

The F/A-18 system is what I was thinking of. Something similar has been proposed for airliners, at least those flying long over water routes. However, as has been noted, this wouldn't be cheap. As for getting everyone on board, one way would be for the FAA, EASA, CASA and Transport Canada to require it on all aircraft flying into their respective jurisdictions.

On the technical side the main issues are coverage, which is being solved, and bandwidth, which is also being solved. People like having Internet access for Facebook, email etc., which will lead to both bandwidth and coverage issues being solved. Storage isn't a major problem as it is quite cheap these days with everyone building data centres all around the world.

As for getting everyone on board, one way would be for the FAA, EASA, CASA and Transport Canada to require it on all aircraft flying into their respective jurisdictions.

Of course this wouldn't have affected Malaysia 370...