[time-nuts] Aircraft ping timing
brooke at pacific.net
Sat Mar 22 17:34:38 EDT 2014
MH370 had both ACARS and ADS-B, they have not been of any help.
ACARS can send it's data using (in order) VHF, Inmarsat, HF.
The problem is that ACARS quit sending information.
MH370 did not have a contract wtih Inmarsat.
ADS-B is built using W.W.II IFF technology (1090/1030 MHz, i.e. 30 MHz IF) and is called secondary radar.
It's the rod looking antenna above the rotating radar antenna at airports.
There are a couple of problems with it, first like VHF it's line of sight so no good over oceans and in the case of
MH370 it stopped sending data.
The Emergency Location Beacons (there are maybe a half dozen on most over ocean airplanes) are coupled with life rafts
and only work when there are people there to turn them on (i.e. people to be rescued). These beacons typically have a
GPS receiver and within minutes have transmitted not only their location but the type of vehicle, number of people on
board, a contact phone number, etc. These 406 MHz beacons talk to the SARSAT system.
There are two scenarios regarding MH370: 1) there was some event, like a small fire with smoke that killed all on board,
or 2) someone in the cockpit (which has a door that can not be opened from the outside) wanted to commit suicide in such
a way that it could not be proved that's what happened so his family would get the insurance.
Brian Lloyd wrote:
> On Fri, Mar 21, 2014 at 11:22 PM, Joe Leikhim <jleikhim at leikhim.com> wrote:
>> In retrospect it is kind of crazy that fleet owners will put tracking
>> devices on $100K semi trucks and cranes yet $100 million aircraft have to
>> rely upon 60 year old technology (Transponders) and ACARS to keep track of
>> them. I don't question the utility of TCAS and Transponders, it is just the
>> issue of not tracking such a valuable asset that is kind of crazy. Can you
>> imagine how much an aircraft like that is worth in spare parts alone? -on
>> the world market. If I were an insurer I would be asking questions of the
> First, just because you imagine there is a problem does not mean that there
> is a problem. It is possible to determine the position of every airplane
> but they just don't go missing all that often, as this recent event
> illustrates. If this were a common problem, we wouldn't be talking about
> it. ;-)
> But the solution already exists and is being deployed - ADS-B. By 2020 each
> aircraft will be beaconing its ID, position, and velocity vector on 978MHz
> and/or 1090MHz. The solution for long over-water tracking is either to
> receive and relay such information, or put up some LEO birds to wiretap and
> forward the broadcasts.
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