RV628PV Squawk..... Never had that before!

[Ash]

There is pretty good chart on wikipedia that shows what a number of transponder codes mean, and what some blocks of numbers are reserved for.

http://en.wikipedia.org/wiki/Transpo...aeronautics%29

Rosie, apparently you are 'Special' :

7701-7707 : Reserved for special use by FAA (USA)

[TylerII]

Was not given 7701 but Chicago center gave me 1201 and Ident just to see where I was before giving me my en-route code. I was leaving Logansport In headed for KOSH and requested FF from Chicago Center. After that exchange the controller let me know that I was outside the Class B and I was instructed to stay clear of all Class B,C,and D airspaces but I got the FF code

Tyler

[newt]

ALT-> SBY
Select 7701.
SBY->ALT

That's how we were all taught to do it, isn't it?

- mark

[KRviator]

Originally Posted by newt

ALT-> SBY
Select 7701.
SBY->ALT

That's how we were all taught to do it, isn't it?

- mark

That's how I was, yes. Never change your code with your transponder in ALT or ON. You run the risk of corrupting the ATC system, at least in Australia.

From the AIP:

Pilots must select the transponder to STANDBY before effecting an SSR code change and returning the transponder to ON/ALT.

Note: This action is required to prevent possible loss of displayed aircraft position/label information and possible misidentification of aircraft in automated Australian ATC systems due to temporary selection (while effecting the change) of a code already in use.

[C. Brenden]

We try (via automation) to preserve your code from facility to facility to reduce the need to change your code. Given the number of planes and the limited number of codes, that isn't always possible. Each center does have a subset of codes that the computer assigns as a first choice; at Albuquerque Center we often see codes 07xx, 26xx, 41xx.
Approach controls do have a set of local codes they use if you stay in the immediate facility. You will notice that if you call inside approach and request flight following outside their facility, it takes a few moments longer because they retrieve a code for you to use as you leave their facility so they can make an automated handoff to the adjacent facility.

[RV7A Flyer]

Originally Posted by newt

ALT-> SBY
Select 7701.
SBY->ALT

That's how we were all taught to do it, isn't it?

- mark

Probably not necessary with a glass cockpit, I'd think...the transponder code entered in to an EFIS (like Dynon w/ its own XPDR) most likely doesn't take effect until the last digit is entered, unlike the old-style XPDRs with separate knobs for each digit.

At least, that's how I'd design the code.

[DFlyer]

Probably not necessary with a glass cockpit, I'd think...the transponder code entered in to an EFIS (like Dynon w/ its own XPDR) most likely doesn't take effect until the last digit is entered, unlike the old-style XPDRs with separate knobs for each digit.

At least, that's how I'd design the code.

That is the way we would design it too.

-Robert
Dynon Avionics

[newt]

That's cool and obvious (I think Garmin does it the same way too).

Another alternative is to have a flip-flop button for the transponder code, the same way we do with COMs. Microair does that on their T2000SFL transponder: You select the code you want on the standby, and hit the flip switch to activate it.

I have one of those, I still turn it back to SBY before changing it, out of habit

In any case: Rosie said he was turning dials, which makes the EFIS side of things less relevant.

- mark

[rjbob]

Originally Posted by newt

ALT-> SBY
Select 7701.
SBY->ALT

That's how we were all taught to do it, isn't it?

- mark

Negative...Controller friend tells me that they know you are changing codes and would rather see a very short time with screwy numbers than the numbers disappearing altogether.

[hgerhardt]

Originally Posted by rjbob

Negative...Controller friend tells me that they know you are changing codes and would rather see a very short time with screwy numbers than the numbers disappearing altogether.

Second that. Heard the same thing from a controller in CA.