Missing Malaysia flight

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Missing Malaysia flight

Post by N7ZAL on Sat Mar 15, 2014 11:35 pm

I posted a question about commercial radar and another on transponder antennas on that other forum before they locked the threads. Political. The place is run like an ignorant dictatorship. I couldn't take anymore and just fled for good.

Anyway, one question was about the antennas used for the transponders. I did get a pm after the thread was locked and the fellow said there are two antennas. Where I am going with the question is: could the antennas be destroyed and therefore the transponders were working but not detected by the commercial airports? This question is based on the missing Malaysia flight.

I'm not familiar with commercial aviation but do have experience with airborne fire control radar systems and can't believe the defense radars in the area didn't detect the flight, although there is some vague allusion to that now. Guess the countries don't want to tip their hand?
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Re: Missing Malaysia flight

Post by Guest on Sat Mar 15, 2014 11:39 pm

That's a good question but I don't know either. I don't see why we can't talk about this, there are plenty of technical and aviation issues where we can have a good discussion and stay away from the politics.  Very Happy 

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Re: Missing Malaysia flight

Post by Wildcat445 on Sat Mar 15, 2014 11:55 pm

I do not have a dog in this hunt, but something about this whole missing aircraft incident does not pass the smell test with me. I can't put my finger on it, though.  Shocked 

We are glad you are here, Bill.

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Re: Missing Malaysia flight

Post by N7ZAL on Sun Mar 16, 2014 12:11 am

I do not have a dog in this hunt, but something about this whole missing aircraft incident does not pass the smell test with me. I can't put my finger on it, though.

Certainly agree and with so much conflicting information it is probably the puzzle of the centuries. Since the US is taking the lead I suspect a lot of the information now is correct. I know fighter aircraft have the radar antennas in the nose cone for technical reasons. However I am totally ignorant about commercial aircraft antenna locations, specifically on the 777. Lots of "what if" scenarios. Of course I am familiar with the long wire antennas on those old aircraft.  Wink 
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Re: Missing Malaysia flight

Post by Wildcat445 on Sun Mar 16, 2014 12:15 am

The news media is calling this "The aircraft mystery of the century". Are they forgetting Amelia Earhart or is this a different century they are talking about? It took them over 50 years to come up with a theory on her disappearance, and I'm not convinced they have it 100% right yet.

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Re: Missing Malaysia flight

Post by N7ZAL on Sun Mar 16, 2014 12:22 am

The news media is calling this "The aircraft mystery of the century".

Safe bet since the century started in 2000.  Wink 
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Re: Missing Malaysia flight

Post by simplex1040 on Sun Mar 16, 2014 2:01 pm

Transponder antennas are a different shape than the communications antennas on the wings. The transponder is set to a certain "frequency" determined by ATC and what it does is when the radar hits it it says " I am XYZ" back to the radar. The transponder has to be "lit up" by the radar. It does not just broadcast. It is like pinging an IP address on the internet. So if someone turned off the transponder and/or changed squawk numbers on it. Radar will loose contact. A commercial jet does have a radar in the nose, however it is a weather radar.
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Re: Missing Malaysia flight

Post by N7ZAL on Sun Mar 16, 2014 3:09 pm

Where are the antennas for the transponder located and about what frequency/size are they? I assume the regular radio transmitters are still in VHF ?
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Re: Missing Malaysia flight

Post by simplex1040 on Sun Mar 16, 2014 3:19 pm

The ground station transmits its interrogation pulses on an "uplink" frequency of 1030 Megahertz, and the transponder replies on a "downlink" frequency of 1090 Megahertz

Radio communication ( voice) is VHF in the 120 MHZ range.  

article on transponders

http://www.avweb.com/news/avionics/183231-1.html?redirected=1


seen some on bottom of planes, some on top, some on tail sections.
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Re: Missing Malaysia flight

Post by N7ZAL on Sun Mar 16, 2014 3:46 pm

Thanks and a good link!
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