I was taught to always select standby mode in the transponder when manipulating the squawk code, at least when using old transponders with turning knobs instead of buttons. The idea behind is to avoid dialing 7700 or similar codes accidentally.
However, this controller here has a different preference.
How are you doing?
If I am using an old four-knob transponder I put it in standby mode. It takes less than 10 seconds to change the code so that really shouldn’t be an issue.
With modern transponders using pushbutton or single-knob code selection this is fortunately not an issue.
Ditto Airborne_Again
It’s good practice but probably not needed with modern equipment.
Would 7700 register with ATC if transmitted for ~0.5 second when cycling through the numbers?
I never used standby mode to switch the code. I would avoid setting all zeros or scrolling thru 77XX.
Would 7700 register with ATC if transmitted for ~0.5 second when cycling through the numbers?
In the UK, the 7700 would need to be present for a few seconds, IIRC.
How does these transponders actually work when switching? It looks to me they go into some kind of “switching mode” as soon as you try to change the numbers. The numbers get highlighted and that doesn’t go away before a few seconds after no more changes are done. Do they stay on the last channel until the “switching mode” is over?
LeSving wrote:
Do they stay on the last channel until the “switching mode” is over?Well, last code. Yes.
NCYankee wrote:
I would avoid setting all zeros or scrolling thru 77XX.This is a recurrent thing to be wary of in northern Germany. Bremen Info got the 774x block of codes for VFR flights. Whether one is coming from Scandinavia (north) or from Langen info (south), invariably you are on 7000 when entering the Bremen FIR. Hence the practice to go through standby, because it’s more logical than changing the individual digits not in order.
How does these transponders actually work when switching?For a Trig or a Garmin transponder, it keeps answering with the current code as long as the cursor is on, ie the new code has not been fully entered. As soon as the last digit is entered or validated, the cursor goes away and the new code becomes the current code. Some other transponders like Funke use a standby code for entry and a flip-flop like on a COM, so no risk until the switch is made.
Luckily there are not many S-mode transponders with rotary knobs, that mandate cleaned it up. There must be a giant pile with all the old KT76’s somewhere.
Dimme wrote:
How are you doing?ALT when I enter the runway before take-off, SBY when I leave the runway after landing.
Arne wrote:
SBY when I leave the runway after landing.Not GND?
I don’t think all transponders have GND. What does it actually do?
