ICAO orders real-time aircraft tracking in wake of MH370
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ICAO orders real-time aircraft tracking in wake of MH370
The amendments to the Chicago Convention, which lays down a bunch of aircraft, airspace, and airport rules for almost every member of the United Nations, are all within Annex 6 (the section that deals with the "operation of aircraft"). The three most significant tweaks are:
* Aircraft must carry "autonomous distress tracking devices" that can "transmit location information at least once every minute in distress circumstances."
* The cockpit voice recorder (CVR) must be able to store at least 25 hours of recording, "so that they cover all phases of flight for all types of operations."
* Aircraft must be "equipped with a means to have flight recorder data recovered and made available in a timely manner."
* Aircraft must carry "autonomous distress tracking devices" that can "transmit location information at least once every minute in distress circumstances."
* The cockpit voice recorder (CVR) must be able to store at least 25 hours of recording, "so that they cover all phases of flight for all types of operations."
* Aircraft must be "equipped with a means to have flight recorder data recovered and made available in a timely manner."
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Lowering the frequency will increase the penetration in air or water and allow it to be detected further. If I recall correctly the ones in use are using 37.5 kHz?
The good thing about generating a lower frequency is it takes less power to do so which will in theory increase the battery life
The good thing about generating a lower frequency is it takes less power to do so which will in theory increase the battery life
Lowering the frequency
On the wake of MH370, I remember a comment about the frequency about being as low as possible since a lot of underwater life emits sounds below 37.5. Not sure if its true or accurate.
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Alternatively, select a pinger frequency that is attractive to whales or some other aquatic life and look for a concentration of the creatures in a search area. Might not be a good idea to attract sharks though.
"transmit location information at least once every minute in distress circumstances."
I suppose you could make it possible for the cabin crew to switch it on, but that would open other cans of worms IMHO.
As far as I can see it would only be of value where the pinger (for the sake of argument) is permanently on, but I suspect the reason for only having it on in "distress circumstances" is a recognition that humanity does not have the satcoms bandwidth available to process full-time pinging from all air traffic.
So I see this as a political salve to public concerns rather than a real technical measure to address the issue.
€0.03 supplied, YMMV,
PDR
Distressed circumstances ?? what does that actually mean-well AF 447 would I am sure qualify but as has been pointed out MH370 could have had a flight profile that looked completely normal- cruise altitude, controlled descent etc just it was a controlled descent to the bottom of the sea . I would have thought that the right idea would be to ping a flight number altitude heading message -very very very short every 15-30 mins 'when operating over oceanic routes. ie wouldn;t be fitted to BA Airbus 32X or Ryanair 738s which operate entirely overland or heavily trafficked over water routes. i think technology has reached the stage that we could find something ditched in the channel without too many clues.
if you take out all those kind of routes, intra europe and US domestic then how much traffic do you really have left to monitor -not that many flights really so I think the computing and telecomms capability could cope pretty easily especially if the data over writes after say three hours .
if you take out all those kind of routes, intra europe and US domestic then how much traffic do you really have left to monitor -not that many flights really so I think the computing and telecomms capability could cope pretty easily especially if the data over writes after say three hours .
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Hmm...
One theory about MH370 is that the reason the transponder stopped transmitting was because one of the crew was interrupted by events while resetting it and lost consciousness before they ever got to finish what they were doing. Does this suggest that a big red glowing 'Panic' button in the middle of the overhead panel might be a good idea so that if it all suddenly goes wrong you take a tenth of a second to punch that before dealing with the emergency and get a set of default actions, perhaps a generic squawk for 'fast developing crisis' plus all the communications options turned on, maybe the satellite upload of the 30 seconds of CVR before the button was hit and the one minute after... then the crew can come back and adjust the settings manually as they normally might when time permits and if they are still able...
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Distressed circumstances -- I had wondered about this, too. but also wondered if the other requirement -- Aircraft must be "equipped with a means to have flight recorder data recovered and made available in a timely manner." -- kind of offsets these issues. But this is kind of ambiguous, too. Would it mean perhaps something like a pod containing the flight data ejected from the aircraft from underwater (in the case of MH370)? Perhaps then transmitting the data to a satellite? Lots of questions.
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If I remember correctly, one of the major issues with MH370 was Malaysian not enabling the online connection due to costs, so only the Ping was left of the connection? Does this mean this is no longer allowed?
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MH370 was perfectly capable of sending ACARS traffic by satellite. It just stopped doing so after it vanished. That's why the pings and the telephone call setup messages were the only signals received that way.
As for 'distressed circumstances', you could probably have a very simple system that could be turned on by a satellite message from the ground if contact is lost. It shouldn't have to be any more complex than the systems already used to track shipping containers and trucks.
Of course, it doesn't help if someone pulls the circuit-breaker.
As for 'distressed circumstances', you could probably have a very simple system that could be turned on by a satellite message from the ground if contact is lost. It shouldn't have to be any more complex than the systems already used to track shipping containers and trucks.
Of course, it doesn't help if someone pulls the circuit-breaker.
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PDR1
If mandatory cooperative surveillance systems such as SSR or ADS-B are both switched off while the aircraft is airborne it could be counted as 'distress circumstances'. Certainly, excessive cabin altitude would also be a distress circumstance. The system would then autonomously start transmitting position and if bandwidth permitted CVR/FDR without input from the crew and regardless of input from 'the crew'/hijackers.
Unless I'm missing something this would not have helped in the MH370 scenario. The "distress circumstances" would either have to be based on some analysis of aircraft systems data or be crew-selected. From what we know of the MH370 case the aircraft systems would not have seen anything that looked like a "distress circumstance" unless the aeroplane actually ran out of fuel, and in the case of a deliberate "suicide" action the pilot would be unlikely to switch it on. It might help in a hijack scenario, but hijackers would probably soon learn how the system is switched off.
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What about transmission of "artifact" information from the ARINC-429 Databus? If done in "packet form", the acquisition and transmission of such data would be fairly simple, and difficult to defeat/impede.
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37.5 kHz ULB
@Rwy in Sight:
Good memory.
https://en.wikipedia.org/wiki/Underwater_acoustics
"Distant ship traffic is one of the dominant noise sources in most areas for frequencies of around 100 Hz, while wind-induced surface noise is the main source between 1 kHz and 30 kHz."
Fig. 2 in this paper shows a noise minimum around 40 kHz:
https://stuff.mit.edu/people/millits...chmj-print.pdf
Good article on underwater beacon search:
Deep-water Black-box Retrieval
No explanation of frequency specification here, but some history:
https://en.wikipedia.org/wiki/Underwater_locator_beacon
Good memory.
https://en.wikipedia.org/wiki/Underwater_acoustics
"Distant ship traffic is one of the dominant noise sources in most areas for frequencies of around 100 Hz, while wind-induced surface noise is the main source between 1 kHz and 30 kHz."
Fig. 2 in this paper shows a noise minimum around 40 kHz:
https://stuff.mit.edu/people/millits...chmj-print.pdf
Good article on underwater beacon search:
Deep-water Black-box Retrieval
No explanation of frequency specification here, but some history:
https://en.wikipedia.org/wiki/Underwater_locator_beacon
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...humanity does not have the satcoms bandwidth available to process full-time pinging from all air traffic.
Humanity's satcom network wouldn't even blink at a short transmission from every aircraft once per minute. And it only needs to be satcom for aircraft outside of surveillance coverage, which means probably less than 10% of the world's airborne fleet at any one time.
For a hundred or so dollars a year, I can put a $200 device on my car dashboard that transmits every 10 minutes. One of these devices on MH370 would have located it immediately. And you think we don't have the bandwidth?
Hasn't one provider already offered the service for free?
Malaysian chose not to spend the money for a service that already existed on their aircraft. ICAO is now saying "you don't get to opt out", and by their use of the word "autonomously", I'm guessing the pilots don't get to turn it off either.
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Vinnie Boombatz:
This topic has been covered before in the AF447 threads and, if I recall, in the MH370 threads:
http://www.pprune.org/tech-log/39510...ml#post5683946
While it is true that there is a noise minima in the deep ocean in the 40KHz band, that is not especially relevant to maximizing detection range. For long ranges, the attenuation at 37kHz is a far more severe limitation than the background noise (and is part of the reason why there is less noise in that band). While the choice of 37kHz for pinger locators was made many decades ago, I expect that the choice was based on the smaller size/weight compared with a low frequency device, and the fact that the short range is adequate for the more common near-shore accidents.
For deep water work we commonly use transmitters in the 7-15kHz band, yielding ranges beyond 10km; 20-30kHz can yield 3-5km; and 40kHz 2-3km. These are not necessarily comparing equal sound pressure level, equal energy/ping, or any other "normalized" comparison, but are ranges practically obtained by traditional oceanographic systems. In this case, typical transmit levels in the 7-15kHz band are 200-210db re 1uPa @ 1m, and the typical aircraft pinger locators transmit at 160db re 1uPa @ 1m.
The problem with low frequency pingers is that they are significantly larger and heavier. A typical 7-15kHz transducer is 7-10cm in diameter and length, compared to less than 2cm for the 37kHz pingers. Certainly a lower frequency pinger or transponder could be carried by an aircraft, but everyone hates to add a kilogram of mass without reason. Also, the 37kHz pinger, being smaller, is much easier to design for shock resistance; that design has been highly optimized over the years. Shock protecting the larger, ceramic transducers might present an issue.
As also noted before, the use of transponders, rather than pingers, would extend the battery life. A transponder does not transmit unless it first receives an interrogation. Thus it only needs to operate its receiver until someone arrives to search, and it can then start transmitting (then also providing range via travel time). It is also possible to further save power by only listening intermittently until an interrogation is heard, and then to listen continuously for a while. All these extra features were complicated decades ago, but are now trivial to implement.
This topic has been covered before in the AF447 threads and, if I recall, in the MH370 threads:
http://www.pprune.org/tech-log/39510...ml#post5683946
While it is true that there is a noise minima in the deep ocean in the 40KHz band, that is not especially relevant to maximizing detection range. For long ranges, the attenuation at 37kHz is a far more severe limitation than the background noise (and is part of the reason why there is less noise in that band). While the choice of 37kHz for pinger locators was made many decades ago, I expect that the choice was based on the smaller size/weight compared with a low frequency device, and the fact that the short range is adequate for the more common near-shore accidents.
For deep water work we commonly use transmitters in the 7-15kHz band, yielding ranges beyond 10km; 20-30kHz can yield 3-5km; and 40kHz 2-3km. These are not necessarily comparing equal sound pressure level, equal energy/ping, or any other "normalized" comparison, but are ranges practically obtained by traditional oceanographic systems. In this case, typical transmit levels in the 7-15kHz band are 200-210db re 1uPa @ 1m, and the typical aircraft pinger locators transmit at 160db re 1uPa @ 1m.
The problem with low frequency pingers is that they are significantly larger and heavier. A typical 7-15kHz transducer is 7-10cm in diameter and length, compared to less than 2cm for the 37kHz pingers. Certainly a lower frequency pinger or transponder could be carried by an aircraft, but everyone hates to add a kilogram of mass without reason. Also, the 37kHz pinger, being smaller, is much easier to design for shock resistance; that design has been highly optimized over the years. Shock protecting the larger, ceramic transducers might present an issue.
As also noted before, the use of transponders, rather than pingers, would extend the battery life. A transponder does not transmit unless it first receives an interrogation. Thus it only needs to operate its receiver until someone arrives to search, and it can then start transmitting (then also providing range via travel time). It is also possible to further save power by only listening intermittently until an interrogation is heard, and then to listen continuously for a while. All these extra features were complicated decades ago, but are now trivial to implement.
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ADS is mandatory in an increasing number of areas. Iridium Next satellite constellation will be carrying the Aireon hosted payload that will pick up ADS-B transmissions worldwide, the problem being discrimination of signals from the densely flown areas.
A more sensible system would be designed and built for tracking and perhaps like satcom have a time slice for each aircraft to transmit. If the transmission is only required once every 5 minutes and only takes a few milliseconds the bandwidth could allow static allocation of a timeslice to each airframe
A more sensible system would be designed and built for tracking and perhaps like satcom have a time slice for each aircraft to transmit. If the transmission is only required once every 5 minutes and only takes a few milliseconds the bandwidth could allow static allocation of a timeslice to each airframe
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Interested to see how are they going to record and store high-quality audio of 25 h when there are still buses flying around with 4.6 MB memory slots running partial nav databases