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Re: Question for pilots.
From: Lu Abel
Date: 2014 Mar 16, 09:21 -0700
From: Lu Abel
Date: 2014 Mar 16, 09:21 -0700
Bruce:
I think you may not be aware that -- to a first order approximation, at least -- aircraft are tracked only when they are over land. That's because their on-board transponders are transmitting on a line-of-sight frequency. So even at a high altitude, their signal is cut off when they're less than 200 miles offshore (which, by the way, is consistent with the "last reported position" for MN370). Ditto for air traffic control frequencies. So it's quite common for aircraft to be "lost" to ground tracking when they are over water. This happens on trans-Atlantic flights and even flights to Hawaii all the time.
In the case of MN370, the pilots said "good night" to the Malaysian air traffic controllers as they were about to go out of range. It was expected that they would be picked up in a couple of hours by Chinese ATC as they approached China's coast.
It's apparent that whoever diverted the flight was pretty sophisticated; knowing, for example, where the aircraft would be out of transponder range when it was over the ocean and therefore a change of track would not be seen.
I believe the Malaysian authorities were made aware that the flight had not come into Chinese air space pretty soon after its expected arrival. I remember the initial news reports saying that Malaysia Air had assembled crisis teams in Beijing even before the scheduled arrival of the flight, presuming that the flight had crashed into the South China Sea. It's only now, days afterwards, that we've learned that it appears as if the flight was hijacked rather than crashed.
Lu
I think you may not be aware that -- to a first order approximation, at least -- aircraft are tracked only when they are over land. That's because their on-board transponders are transmitting on a line-of-sight frequency. So even at a high altitude, their signal is cut off when they're less than 200 miles offshore (which, by the way, is consistent with the "last reported position" for MN370). Ditto for air traffic control frequencies. So it's quite common for aircraft to be "lost" to ground tracking when they are over water. This happens on trans-Atlantic flights and even flights to Hawaii all the time.
In the case of MN370, the pilots said "good night" to the Malaysian air traffic controllers as they were about to go out of range. It was expected that they would be picked up in a couple of hours by Chinese ATC as they approached China's coast.
It's apparent that whoever diverted the flight was pretty sophisticated; knowing, for example, where the aircraft would be out of transponder range when it was over the ocean and therefore a change of track would not be seen.
I believe the Malaysian authorities were made aware that the flight had not come into Chinese air space pretty soon after its expected arrival. I remember the initial news reports saying that Malaysia Air had assembled crisis teams in Beijing even before the scheduled arrival of the flight, presuming that the flight had crashed into the South China Sea. It's only now, days afterwards, that we've learned that it appears as if the flight was hijacked rather than crashed.
Lu
From: Bruce J. Pennino <bpennino.ce@charter.net>
To: luabel@ymail.com
Sent: Sunday, March 16, 2014 8:56 AM
Subject: [NavList] Question for pilots.
Hello:I've always imagined that if an airliner went drastically off course, or had a sudden change in altitude, someone would start asking questions?? Have other planes on the look-out? Send up a jet to investigate? Are the Malaysians that incompetent or asleep? Quick response only true in U.S., Europe, etc?Bruce----------------------------------------------------------------
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