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Mon Mar 17, 2014, 05:37 PM

I have a question about planes "Transponders".....

Can anyone give me one good reason why transponders have an "off" switch?

As important as they are why would this be an option?

Just as the engine "ping" cannot be disengaged ... you would think airlines would make transponders continue to communicate while the plane is running.

My humble question of the day....

MH

9 replies, 1100 views

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Arrow 9 replies Author Time Post
Reply I have a question about planes "Transponders"..... (Original post)
MysticHuman Mar 2014 OP
quinnox Mar 2014 #1
moondust Mar 2014 #2
MysticHuman Mar 2014 #5
jmowreader Mar 2014 #3
MysticHuman Mar 2014 #7
longship Mar 2014 #4
Mojo Electro Mar 2014 #6
Kilgore Mar 2014 #8
MysticHuman Mar 2014 #9

Response to MysticHuman (Original post)

Mon Mar 17, 2014, 05:39 PM

1. yea, I had the same question. The answer is

 

when all the planes are on the ground, then it would cause a big mess for the controllers trying to taxi the planes to take off safely.

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Response to MysticHuman (Original post)

Mon Mar 17, 2014, 05:40 PM

2. I asked that question yesterday.

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Response to moondust (Reply #2)

Mon Mar 17, 2014, 06:04 PM

5. Thanks moondust....

My only thought on it would hamper ground control is that it shouldn't be hard to put the a transponder on a different frequency thus eliminating interfering whenn it is on the ground.

I did read some are moving to overcome the interference issue which is good..but this should have been done years ago.

Thanks again

MH

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Response to MysticHuman (Original post)

Mon Mar 17, 2014, 05:43 PM

3. Probably so you can maintain the plane without bothering the tower

If you need to run the engines as part of a service, you've got to power up the plane but ATC doesn't need to know about it because you're not going anywhere.

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Response to jmowreader (Reply #3)

Mon Mar 17, 2014, 06:08 PM

7. As I stated to Moondust - using a different frequency or band would

solve this issue.

If you need two transponders ...one that does show up to the tower... and one that doesn't and can't be turned off ... have two then.

For me there should be no reason that a transponder transmitting on a separate channel should be possible.

Thanks for your input.

MH

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Response to MysticHuman (Original post)

Mon Mar 17, 2014, 05:51 PM

4. It is a good question. The answer is in the other responses.

It is needed.

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Response to MysticHuman (Original post)

Mon Mar 17, 2014, 06:06 PM

6. As has been said in the thread,

there are times when it is apropriate for the transponder to be off. I believe it's really only used while in flight.

It is actually just put in "standby" mode where it is not transmitting, though I believe it can be disabled by pulling the circuit breaker that supplies power to it.

Here is a picture of the transponder control panel on a 777 console, which is positioned in between the 2 pilots on the right side next to the seat, with the transponder switch shown in the "standby" position.







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Response to MysticHuman (Original post)

Mon Mar 17, 2014, 06:56 PM

8. Just open the circuit breaker

Not having an off switch would just mean opening the appropriate circuit breaker to kill the system.

Kilgore

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Response to Kilgore (Reply #8)

Tue Mar 18, 2014, 03:45 AM

9. I am sure this could be prevented

I am just saying there has to be a way to keep some type of communication from the plane to the ground that can't be stopped or overridden.

Mh

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