AIM on ground transponder use

[Orest Skrypuch]

Gavin,
..... How does stand by mode fits into these 3 below?

Anticipating ...

And how is Standby different from OFF? It is a historical issue. Older transponders took a long time to warm up and be functional. You'd turn them to STBY when you start up the plane, and they'd be ready to transmit immediately, once on the runway.

* Orest

[arb65912]

Thank you, Orest, understood.

Now, not to drag the subject but if stand by mode is invisible for ATC, what is the stand by mode used for in newer transmitters when transponders do not need to be warmed up before becoming functional?

Cheers, AJ

[Keith Smith]

Pilots expect it to be there.

[gavink42]

Also... there used to be some concern about active transponders on the ground causing TCAS alerts to be generated on aircraft that are on short final. That was one of the justifications for keeping transponders in standby on the ground. But, I haven't heard that brought up in some time.

Gavin

[Keith Smith]

Gavin,

I was referring to AJ's question about the need for off vs stdby given that the newer electronics don't have the warmup time.

[kullery]

Any time something changes, it takes a while for it to "kick-in" with everyone. I hadn't been aware of this change till reading this forum last week (thanks PE community for the education!!!).

I toured KCAK tower and TRACON this past weekend. I asked tower controllers about ALT during ground operations. They indicated that it occasionally gives them a "false reflection" and that they prefer ALT only be used at the active runway. They do not have ASDE and they were not aware of the change in the AIM.

So don't be surprised if you get a R/W request to switch to STBY during taxi, especially at smaller towered fields without ASDE.


ken