Transponder code

[Capn Bloggs]

Originally Posted by Bloggs

TCAS uses the transponder system. Transponder off? TCAS inop.

I was a bit flippant there. Here's what the 717 displays:

Transponder Setting/TCAS Status display

STBY / TCAS Off

Alt Off / TCAS Off

Alt On / TCAS STBY

TA / TA ONLY

TA/RA / Nothing

[ATCast]

Capt Pit Bull

No problem!

I followed your advice and used the search function and found this marvellous old post.
Not much has changed in 13 years on pprune. Not the questions, nor your attitude

[FlightPathOBN]

From Transport Canada

RAC - 1.0 GENERAL


"Do not select “STANDBY” while changing codes as this will cause the target to be lost on the ATC radar screen.

Pilots should adjust transponders to “STANDBY” while taxiing for takeoff, to “ON” (or “NORMAL”) as late as practicable before takeoff, and to “STANDBY” or “OFF” as soon as practicable after landing. In practice, transponders should be turned on only upon entering the active runway for departure and turned off as soon as the aircraft exits the runway after landing."

[Capn Bloggs]

And the AIP Australia says...

7.1.9 A pilot operating a Mode S transponder must:
a. Not relevant.

b. On receipt of ATC clearance, or requesting the earlier of Push Back or Taxi, select TA/RA/XPDR/ON AUTO as applicable.

Note 1: If AUTO mode is not available Select ON (e.g. XPDR) and assigned Mode A code.

Note 2: Australia does not require TA/RA to be de--selected while aircraft is on ground.

c. When parked and shutting down engines, select STANDBY.

d. Not relevant.

7.1.10 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.

[Haroon]

7.1.10 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.

does anybody know if this applies to any other place apart from Australia

[Capt Claret]

I think the Aussie system is of French design. Should one inadvertently set the wrong TXPR code on the ground in one's Boeing or Airbus, and that code has been assigned to a Cessna 172 on the other side of the country, the automatic pickup once airborne causes all sorts of problems, because the 172 is now exceeding its design perameters and has mysteriously crossed the country. But one's Boeing or Airbus is still safely on the ground.

[Saratogapp]

How long does it take to change your code? I would think that, immediately you have been instructed to change code (I.e. ATC is EXPECTING a change) going STBY for, say 15 seconds while you dial up the new code and return to AUTO or ALT, is an expectation. What am I missing here?

[Turbavykas]

How long does it take to change your code? I would think that, immediately you have been instructed to change code (I.e. ATC is EXPECTING a change) going STBY for, say 15 seconds while you dial up the new code and return to AUTO or ALT, is an expectation. What am I missing here?

Accidents happen when multiple factors combine. Lets say that there is 1:1000000 chance of engine failure during those 15 seconds. You get multiple warnings, you forget to turn on transponder, you start to descent, nobody know where you are, TA/RA is not working in other aircraft and just happens A380 flying 1000 ft below you. 500 lives lost just for turning transponder to STBY.

[Capt Claret]

Accidents happen when multiple factors combine. Lets say that there is 1:1000000 chance of engine failure during those 15 seconds. You get multiple warnings, you forget to turn on transponder, you start to descent, nobody know where you are, TA/RA is not working in other aircraft and just happens A380 flying 1000 ft below you. 500 lives lost just for turning transponder to STBY.

Not to mention the system chaos as one momentarily selects several different TXPDR codes whilst changing the squark, activating a whol lot of flight plans.

[DaveReidUK]

Not to mention the system chaos as one momentarily selects several different TXPDR codes whilst changing the squark, activating a whol lot of flight plans.

We were told as far back as post #5 that

equipment manufacturers - of both transponders and radar processors - soon started building in what are often called 'slugs', slight delays before believing that a changed code really was the next selected code and transponders effectively switched themselves to STBY while code selections changed

Was that rubbish, then ?

[Haroon]

is there any ATC personnel here reading this post?

[Spitoon]

'equipment manufacturers - of both transponders and radar processors - soon started building in what are often called 'slugs', slight delays before believing that a changed code really was the next selected code and transponders effectively switched themselves to STBY while code selections changed'

Was that rubbish, then ?

Not rubbish, but not to be relied upon as universally applicable - there will be old equipment out there and few people using radars will fully understand what processing goes on behind the screens. Just as posts in this thread show that many pilots are not fully aware of how their equipment works.

But as one of my old instructors used to say, it's always a good day when you learn something new.....especially if no one gets killed.

[Natstrackalpha]

A classic tale indeed. Go to Stand-by always. This is a hairy chesnut.

Just go to standby. Then change. Don`t do it any other way.

FOR EXAMPLE. TRUE STORY.

Airliner approaching the US Eastern coast, from the East, like Europe, ok?

Pilot inadvertantly selects a naughty squawk, US ATC kindly invites them to divert.

Pilot argues, it was his error and everything is tickety boo. US ATC, not interested. Divert or else. Pilot diverts. Conclusion: silly pilot.

Standby, before changing squawk, standby before operating from cold. Standby when asked to squawk `standby`
Standby before switching the box off. Standby until airborne for initial squawk.

[Natstrackalpha]

saratogapp. You are missing my post, see further. Also, if you or anyone-else here have not been trained to go through stand by as written, by me, in this thread, then ask for your money back. Also, I don`t care what RAC says if it contradicts what I posted. Whether its RAC from Canada or RAC from IRAQ or WRAC from the Army, or the UK or EASA - you must always change to stand by first.

[Natstrackalpha]

Quote:
7.1.10 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. does anybody know if this applies to any other place apart from Australia

HAROON You are dead right mate, it applies to the UK as well.

Here is another way of looking at it:


ALWAYS GO TO STAND BY BEFORE CHANGING CODE.

JUST DO IT!!