Slcpilot
Posts: 568
Joined: Thu Aug 07, 2003 3:32 am

Mode A, B, C Transponder Questions..

Fri Oct 31, 2003 1:49 am

Somebody asked me the other day what Mode A, and Mode B were with respect to transponders. I always thought Mode was just the "code" while C included the encoded alitiude. What is mode B?

Also, with respect to VFR cruising altitudes in the U.S., why does 14 CFR 91.159 refer to VFR cruising altitudes at the flight levels? I thought all the traffic was IFR up there.

Thanks in advance !

SLCPilot
I don't like to be fueled by anger, I don't like to be fooled by lust...
 
MxCtrlr
Posts: 2312
Joined: Tue Nov 13, 2001 11:22 am

RE: Mode A, B, C Transponder Questions..

Fri Oct 31, 2003 1:52 am

You are correct on the A and C but you forgot the new Mode S (which is transponder with Altitude Encoding and TCAS).

MxCtrlr  Smile/happy/getting dizzy
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cdfmxtech
Posts: 1319
Joined: Wed Jul 05, 2000 11:37 am

RE: Mode A, B, C Transponder Questions..

Fri Oct 31, 2003 2:17 am

Mode A = Identity
Mode C = Altitude
Mobe B was planned for, but never used, at least not in civial aviation.
 
avioniker
Posts: 1099
Joined: Tue Jan 01, 2002 5:38 am

RE: Mode A, B, C Transponder Questions..

Fri Oct 31, 2003 2:26 am

Actually Mode S is so named because it Selectively interrogates other nearby aircraft transponders in coordination with TCAS to determine proximity and threat. It also transmits the registration or international identification code of the aircraft so it may be specifically identified for interrogation by other Mode S transponders in the area.
The name isn't accurate in that a Transponder responds to interrogation and an Interrogator initiates interrogation or communication (i.e. DME Interrogator vs. ATC Transponder) The name stays because the primary purpose is still to respond to ATC queries for control.
One may educate the ignorance from the unknowing but stupid is forever. Boswell; ca: 1533
 
liamksa
Posts: 301
Joined: Mon Oct 29, 2001 1:13 pm

RE: Mode A, B, C Transponder Questions..

Fri Oct 31, 2003 10:27 am

Also, with respect to VFR cruising altitudes in the U.S., why does 14 CFR 91.159 refer to VFR cruising altitudes at the flight levels? I thought all the traffic was IFR up there.

Here in OZ generally the max VFR altitude is FL200 due to VFR altimeter accuracies.

Rob.
 
Guest

RE: Mode A, B, C Transponder Questions..

Fri Oct 31, 2003 11:17 am

Hey SLC! I used to live in Utah County, and did most of my flying in Provo. I've flown to SLC numerous times, though. Did my 10 night tower landings for the Commercial on 17. Fun stuff.

Drop me a line, eh?

-Normal

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