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    Re: Question for pilots.
    From: Lu Abel
    Date: 2014 Mar 16, 15:45 -0700
    Thanks for the clarification, Gary.  I thought there was a requirement to have ELTs on private aircraft, but was unable to verify that with the private pilots I know. 

    There's a good article on ELT/EPRIB's on Wikipedia. 


    From: Gary LaPook <garylapook@pacbell.net>
    To: luabel@ymail.com
    Sent: Sunday, March 16, 2014 1:56 PM
    Subject: [NavList] Re: Question for pilots.

    All private airplanes in the U.S. have been required to have an ELT installed by a law passed by the Congress after one of their own, House Majority Leader Hale Boggs' plane disappeared in Alaska 1n 1972. They send out a signal automatically after a crash on 121.5 and 243 mhz. For a long period these frequencies were monitored by satellites but that ended a few years ago. 406 mhz ELTs are available now but there is no requirement to install them so nobody does.


    From: Lu Abel <luabel{at}ymail.com>
    To: garylapook---.net
    Sent: Sunday, March 16, 2014 12:56 PM
    Subject: [NavList] Re: Question for pilots.

    Bruce, I suspect (with absolutely no facts to back me up) that it may be a matter of international cooperation and politics.

    Your MOB device transmits to a satellite system that is an evolution of a long-standing way of locating ships and aircraft in distress.  

    BTW, what mariners know as an EPIRB (emergency position indicating radio beacon) flyers know as an ELT (emergency location transmitter).  Same functionality.   Just as with watercraft, all commercial flights are required to carry ELTs.  Many private planes carry one, too, but it's not legally required.

    But they are only for location in an emergency.   One would only infrequently see an actual signal.   And, to my political point, I think everyone can agree on the need to find an aircraft or ship in distress.

    Tracking of ALL flights would require satellites and corresponding ground systems that could handle a million times as much data.   You ain't going to get that out of one of the EPIRB/ELT satellites.   It would require a whole new system of satellites.

    Plus, even more important, what's to stop a hijacker from simply turning off the transponder as they did with the ground-based transponders (similar to AIS for ships)?   Before someone says "shouldn't be able to turn it off," consider the fact that the average aircraft spends at least half its time on the ground, not in the air.  Would we really want to overload the tracking system (whether ground-based, as we have today, or satellite-based) with irrelevant signals?

    Some thoughts....


    From: Bruce J. Pennino <bpennino.ce---.net>
    To: luabel{at}ymail.com

    Sent: Sunday, March 16, 2014 10:36 AM
    Subject: [NavList] Re: Question for pilots.

    Hi Lu:
    It is interesting to me that for a few hundred dollars there is a "man overboard" device that sends a "position" signal to a satellite, but every plane that flies over water does not have one (apparently).The cost of this search is so enormous compared to a relatively simple device......yes/no? 

    ----- Original Message -----
    From: Lu Abel
    Sent: Sunday, March 16, 2014 1:11 PM
    Subject: [NavList] Re: Question for pilots.


    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.


    From: Bruce J. Pennino <bpennino.ce---.net>
    To: luabel{at}ymail.com
    Sent: Sunday, March 16, 2014 8:56 AM
    Subject: [NavList] Question for pilots.

    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?
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