The Naked Scientists

The Naked Scientists Forum

Author Topic: How hard would it be to track 100% of the global passenger aircraft always?  (Read 1848 times)

Offline CliffordK

  • Neilep Level Member
  • ******
  • Posts: 6321
  • Thanked: 3 times
  • Site Moderator
    • View Profile
How hard would it be to design a system that would track 100% of the global passenger aircraft 100% of the time?  Or, perhaps anything larger than a single engine Cessna? 

The planes should be able to get fairly accurate 3-D GPS information, latitude, longitude, altitude, direction of travel, velocity vector, fuel status, etc.  Design the system to broadcast an ID and status packet, say once a minute. 

For the most part, the data could be just logged, but deviations from normal should be flagged and analyzed.  And, of course, schedule status could be better monitored.

I assume there'd be a few dead spots, and the occasional network outage.  But, for something like the recent lost Malaysia jet, there would be  alot less guessing on where it would be.  The survival rate for planes lost at sea is low, but if some passengers managed to get their life jackets on, they might be found at a reasonable time.
« Last Edit: 11/03/2014 05:13:36 by CliffordK »


 

Offline alancalverd

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 4699
  • Thanked: 153 times
  • life is too short to drink instant coffee
    • View Profile
In principle, very easy. Pretty well everyone (including drivers of single engine Cessnas, and even sailplanes) now has access to full 4-dimensional GPS position and time information on board. The $500 gadget I carry in my pocket has my planned route, actual track, speed and present direction plotted over standard terrain maps and tells me everything I need to know, including a few things like airspace infringements and lost fumblings that I'd prefer not to.

But whilst this is fine for locating an intact small plane over land, it might not be a lot of help finding the wreckage of an exploded airliner at sea. The parts start off travelling at 500 mph: some slow down very rapidly when they hit fresh air, whilst dense bits like engines and suitcases describe a classically neat parabola. Falling 5 miles through varying winds and active clouds will further disperse the debris, which will eventually sink at differing rates through a moving sea. By the time you have initiated a search - say a minimum of 2 hours for a short scheduled flight and maybe 5 hours for an overdue long haul - and reached the epicentre (another 5 hours or more to get to the middle of the Pacific, even at 50,000 ft ) the stuff you are looking for will have drifted anything from zero up to 100 miles from wherever it hit the water. Thus the best guess, based on dead reckoning and known winds and tides, is probably as good as you can get when it comes to finding survivors and black boxes.

Lifejackets are a good idea if you are contemplating and have practiced a controlled ditching, or if worn with a parachute. But the number of sucessful ditchings of large passenger aircraft is pretty small, and nearly all from an initial low-level incident http://www.airliners.net/aviation-forums/general_aviation/read.main/1797199     
« Last Edit: 11/03/2014 07:28:02 by alancalverd »
 

Offline CliffordK

  • Neilep Level Member
  • ******
  • Posts: 6321
  • Thanked: 3 times
  • Site Moderator
    • View Profile
One shouldn't have to wait for the airplane to fail to land at the airport.

Miss 5 minutes of pings, and it should trigger an immediate attempt to contact the cockpit verbally.  There are probably some radio dead zones, but if a communication web was created with commercial shipping, and perhaps satellite uplinks, the dead zones would be minimized (and generally known or predicted).

There is no reason why the initial stages of an emergency response couldn't start within 10 minutes of the first missed ping.  Of course there would be the occasional communications failure, but with a dual redundant (voice/data) system, it should be minimized.

Earlier I calculated that it can take over a half hour for a dense object to fall to the ocean floor.    A low density object with significant amounts of trapped air might take much longer to sink to the bottom, and thus being spread out further.
« Last Edit: 11/03/2014 09:31:22 by CliffordK »
 

Offline alancalverd

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 4699
  • Thanked: 153 times
  • life is too short to drink instant coffee
    • View Profile
ACARS  http://en.wikipedia.org/wiki/Aircraft_Communication_Addressing_and_Reporting_System can pretty well do the job and did indeed provide a lot of information about the Air France 447 crash. However you need to consider the effect (particularly the cost) of false alarms. It is entirely up to the pilot to decide how he is going to handle weather and clear-air turbulence, so a departure from intended speed, track or altitude is not necessarily a problem - it is more likely a solution. When things get hairy, talking to the ground has a very low priority - and who do you contact to cancel a search and rescue that you don't know has started? Could be the navy (whose? where? what frequency (assuming you have access to military frequencies, which civil aircraft generally don't)) or coastguard, police helicopters.... 

Web communication via commercial shipping could be interesting if ships carried airband radio and the operators had the mandatory licenses, but it's just another expense....and thanks to the blessed European Union we now have some 2000 VHF channels to choose from, so negligible chance of contacting an aircaft unless it's already talking to another plane or air traffic service, in which case the call is redundant.

There's not a lot of difference betweeen 10 minutes and 45 minutes as far as the survivors are concerned, if the rescue is going to take 5 hours. Standard protocol is to alert "overdue" if you haven't reported a waypoint, landed, diverted, or cancelled the flightplan within 45 minutes of the expected time, but even the simplest local flight can cause uproar. I phoned a day ahead for information about a licensed airport in case I needed a night landing after a business trip: this was recorded in error as a flight plan. Job done on time, I blissfully flew back to our little grass strip in daylight and went to bed whilst the police phoned umpteen airports, radar and fire services to locate my charred corpse, culminating in the manager of the grass strip grumpily opening the hangar at 3 am to discover that I'd landed after the office closed.

On a long haul scheduled route, if you make hourly position reports there's a pretty good chance of finding the wreckage. You won't find many survivors from a sudden disintegration at 40,000 ft however long it takes.
« Last Edit: 11/03/2014 12:11:46 by alancalverd »
 

Offline syhprum

  • Neilep Level Member
  • ******
  • Posts: 3816
  • Thanked: 19 times
    • View Profile
The idea that engine maintenance data was received from the missing Malaysian airliner for up to four hours after the last communication was received from the pilots seems to be firming up.
if this data was time stamped and the position of the satellite that received it was known could this perhaps provide some information as to where the aircraft was and in which direction it was travelling.
A suggested route. 
« Last Edit: 14/03/2014 15:32:06 by syhprum »
 

The Naked Scientists Forum


 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums