Transponder to standby
Guest
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Transponder to standby
I have religiously turned my transponder to "standby" before changing the squawk code - and I've religious taught students to do the same.
Am I doing the right thing...or wasting my time (and theirs)?
Does a sweep of the radar cause garbled codes during number changing...or, to be more precise, does it matter to you guys (and gals).
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LIVE in peace...or REST in it!
Am I doing the right thing...or wasting my time (and theirs)?
Does a sweep of the radar cause garbled codes during number changing...or, to be more precise, does it matter to you guys (and gals).
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LIVE in peace...or REST in it!
Guest
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I used to go to Standby before changing code.
These days however, I reckon its the lesser of two evils to leave it on.
As is mentioned in posts above, it probably won't cause a problem as the radar hardware will solve it.
It should also be considered that although you could cause a temporary error in your 4096 code, at least by keeping your transponder 'On' your Altitude Reporting data is still going out. This is important so that TCAS can operate correctly. By going to Standby you become invisible to the other guys TCAS.
Whilst I don't have any figures to prove it, having looked at TCAS incident reports I get the impression that the hand over from one controller to another is a risk factor. Since a change in squawk is part of the hand over process, it would seem sensible to ensure that your Altitude reporting is kept active. TCAS doesn't care about your 4096 code.
Any thoughts, anyone?
CPB
These days however, I reckon its the lesser of two evils to leave it on.
As is mentioned in posts above, it probably won't cause a problem as the radar hardware will solve it.
It should also be considered that although you could cause a temporary error in your 4096 code, at least by keeping your transponder 'On' your Altitude Reporting data is still going out. This is important so that TCAS can operate correctly. By going to Standby you become invisible to the other guys TCAS.
Whilst I don't have any figures to prove it, having looked at TCAS incident reports I get the impression that the hand over from one controller to another is a risk factor. Since a change in squawk is part of the hand over process, it would seem sensible to ensure that your Altitude reporting is kept active. TCAS doesn't care about your 4096 code.
Any thoughts, anyone?
CPB
Guest
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Kinda depends on how big a change it is, and what numbers you'll be going thru on the way. If you hit 77, 76 or 75 then your code as displayed on the tube starts flashing, alarms start beeping and the D&D cell at LATCC start getting excited.
If it's only a quick change (as others have said, no more than 4 or 5 secs) I wouldn't worry too much!
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Once more unto the breach, Dear Friends...
If it's only a quick change (as others have said, no more than 4 or 5 secs) I wouldn't worry too much!
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Once more unto the breach, Dear Friends...
Guest
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Is it not possible to keep one transponder on one code while selecting the newly assigned code on the second transponder. I dont have a huge amount of airline knowledge but this would seem like common sense. This way you get to keep your readout for TCAS while not setting off emergency codes or activating the code of another aircraft. When you have correctly selected the newly assigned code, then switch transponders??????
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And that's what I think about that.
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And that's what I think about that.
Guest
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Not this one again.
Friend of mine (pilot) did exhaustive research and discovered that it is NOT necessary to select standby when changing transponder codes - as has been previously stated the mode charlie needs to be left on for TCAS, etc.
Obviously you should not take all day about changing codes but so long as you select the new code in a "normal" manner there is no problem.
In short, no need to select standby.
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Friend of mine (pilot) did exhaustive research and discovered that it is NOT necessary to select standby when changing transponder codes - as has been previously stated the mode charlie needs to be left on for TCAS, etc.
Obviously you should not take all day about changing codes but so long as you select the new code in a "normal" manner there is no problem.
In short, no need to select standby.
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Guest
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I also do the same as squeakmail and have often wondered whether anybody else does,however,I think I will not bother anymore as the ATC software requires two hits before capture and recognition. There is one scenario that could create a problem, that is if you get distracted before you have completed the change.On reflection I think I will continue the practice of turning to standby.Will you continue to teach your students the same?
Guest
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FBW et al,
May I respectfully suggest that you DON'T turn the transponder to SBY when changing squawk.
In modern ATC centre's, selection of SBY will remove your target/data from the screen until the computer has a few sweeps to fit you back into the system. It will continue to track a "live" transponder while the numbers alter in a sort of 'memory' mode while the squawk changes to look for a new number and database reference.
Thus, if the centre is not one which processes raw data [and few do these days outside a TMA], you can very inconveniently disappear off the screen on selection of SBY.
Is that what you or the ATCO looking after your interests really want??
G'day
May I respectfully suggest that you DON'T turn the transponder to SBY when changing squawk.
In modern ATC centre's, selection of SBY will remove your target/data from the screen until the computer has a few sweeps to fit you back into the system. It will continue to track a "live" transponder while the numbers alter in a sort of 'memory' mode while the squawk changes to look for a new number and database reference.
Thus, if the centre is not one which processes raw data [and few do these days outside a TMA], you can very inconveniently disappear off the screen on selection of SBY.
Is that what you or the ATCO looking after your interests really want??
G'day
Guest
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Ooo, er, missus!!
Are we now saying that turning it ON will take two or three sweeps of radar to acknowledge that it is there...but turning it OFF is instant lack of data?
Looking back through the messages it seems that TCAS is the thing we are trying to protect...rather than ATC confusion.
I was surprised to see mention of "code change" on handover...I would have thought (although, presumably, incorrectly) that at the levels where heavy metal meets PA28...all code changes would be finished and the little guy (me...hence the reference to teaching students) would already be identified and locked into the airspace system that the heavy metal deems to be theirs (and only theirs).
On the question of "Will I still teach that way?"...to be honest, I don't know. I'll probably - as I do with many aviation thingies - show 'Gromit' (I don't fly with Bloggs anymore) both ways, discuss the comments and options and let him/her suit himself/herself in the future. Whatever I tell him/her...I may be wrong.
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LIVE in peace...or REST in it!
Are we now saying that turning it ON will take two or three sweeps of radar to acknowledge that it is there...but turning it OFF is instant lack of data?
Looking back through the messages it seems that TCAS is the thing we are trying to protect...rather than ATC confusion.
I was surprised to see mention of "code change" on handover...I would have thought (although, presumably, incorrectly) that at the levels where heavy metal meets PA28...all code changes would be finished and the little guy (me...hence the reference to teaching students) would already be identified and locked into the airspace system that the heavy metal deems to be theirs (and only theirs).
On the question of "Will I still teach that way?"...to be honest, I don't know. I'll probably - as I do with many aviation thingies - show 'Gromit' (I don't fly with Bloggs anymore) both ways, discuss the comments and options and let him/her suit himself/herself in the future. Whatever I tell him/her...I may be wrong.
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LIVE in peace...or REST in it!
Guest
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I have to say that I thought it was all a bit much ado about nothing until my 170a flight test for my instrument rating. I was changing xpndr codes (on standby ).
I glanced down to check the code before I switched the thing on and blow me if I didn't find the thing reading 7700 and an examiner waiting expectantly...
The chances must have been quite a lot to one, but I have been a convert to changing to standby when changing codes ever since
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they bought their tickets - they knew what they were getting into
I glanced down to check the code before I switched the thing on and blow me if I didn't find the thing reading 7700 and an examiner waiting expectantly...
The chances must have been quite a lot to one, but I have been a convert to changing to standby when changing codes ever since
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they bought their tickets - they knew what they were getting into
Guest
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Thanks for the advice Feather # 3
Your comments are interesting and I will think about them over the next couple of days. I'm not sure disappearing for a couple of sweeps is such a problem, especially as ATC will presumably expect this to happen.
It would be interesting to know what the manufacturers recommend, anybody got any information?
Your comments are interesting and I will think about them over the next couple of days. I'm not sure disappearing for a couple of sweeps is such a problem, especially as ATC will presumably expect this to happen.
It would be interesting to know what the manufacturers recommend, anybody got any information?
Guest
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First, the point about changing codes 'on the other transponder' might be worth considering, but most aircraft I have flown have two transponders drivenm by one selector head, so only one code is ever displayed - you just select which box (and which Mode C feed) is active.
Second, it is my understanding that whilst ATC radars do take their time to receive and process SSR transmissions, the same is not true of airborne radar as used in SAR, for example on the British Nimrod, which does (I am told) show an emergency squawk on first reception. Would a Nimrod crew-member care to comment... perhaps someone at LATCC could make a 'phone call to ask the question....
Second, it is my understanding that whilst ATC radars do take their time to receive and process SSR transmissions, the same is not true of airborne radar as used in SAR, for example on the British Nimrod, which does (I am told) show an emergency squawk on first reception. Would a Nimrod crew-member care to comment... perhaps someone at LATCC could make a 'phone call to ask the question....
Guest
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Ok FOKJOK. Point taken about the two transponders. But after ATC advise you of a new transpondser code, how long does it take to input such a code?Surely it's just a case of twiddling a few numbers. Why the confusion? I ask purely from a learning point of view????
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And that's what I think about that.
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And that's what I think about that.
Guest
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If the debate takes the track of "two transponders"...can we steer it back to the point of view that ALL aircraft could benefit from an answer...not just airliners.
Remember, there are more PA28's on the UK register than ANY other aircraft type...and I doub't any one of them has a spare transponder...nor a "non handling pilot" to "twiddle the numbers" whilst the handling pilot scans the TCAS.
Please, don't forget your roots when continuing this discussion.
Remember, there are more PA28's on the UK register than ANY other aircraft type...and I doub't any one of them has a spare transponder...nor a "non handling pilot" to "twiddle the numbers" whilst the handling pilot scans the TCAS.
Please, don't forget your roots when continuing this discussion.
Guest
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Sorry if you thought I was going off the point squeakmail. I thought it would have been obvious by me saying the Question asked was from a learning perspective that my "ROOTS" are not in the left seat or the right seat but in a seat outside the aircraft. Hence the question.
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And that's what I think about that.
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And that's what I think about that.
Guest
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I'm at work (LATCC) tommorrow morning so I will pop into the military and ask about the SAR radar as mentioned by Fokjok. Regarding the point made about the importance of TCAS and maintaining the continuity of transmission, it is worth remembering that most PA28's, which is where this thread began, allthough fitted with SSR are not mode C enabled.
Guest
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To comment on a couple of posts:
Squeaks; Although I drive B744's for a crust [loaf even?], during any year I fly a variety of a/c down to the lovely DH-82A [Ahhh! de Havilland!!] The same technique applies to all; simply change the numbers while squawking.
However, if you DO operate in an environment with Jurassic radar systems, the old technique may apply. I would respectfully suggest that most Western world systems now rely on computer processing of SSR data, and that my earlier comments are valid.
FBW; Please don't perpetrate the myth they've tried here in Aust that you MUST have Mode C [Altitude reporting] to be any use to TCAS. A basic transponder still alerts the crew to your position. It may not give height [naturally], but helps the eyeballs to scan in the right direction. If you have a transponder, turn it on to your country's basic VFR squawk [as a minimum] EVERY time you are airborne! Please!!
G'day
Squeaks; Although I drive B744's for a crust [loaf even?], during any year I fly a variety of a/c down to the lovely DH-82A [Ahhh! de Havilland!!] The same technique applies to all; simply change the numbers while squawking.
However, if you DO operate in an environment with Jurassic radar systems, the old technique may apply. I would respectfully suggest that most Western world systems now rely on computer processing of SSR data, and that my earlier comments are valid.
FBW; Please don't perpetrate the myth they've tried here in Aust that you MUST have Mode C [Altitude reporting] to be any use to TCAS. A basic transponder still alerts the crew to your position. It may not give height [naturally], but helps the eyeballs to scan in the right direction. If you have a transponder, turn it on to your country's basic VFR squawk [as a minimum] EVERY time you are airborne! Please!!
G'day
Guest
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Need to know,
regarding setting the code on the other transponder, and then changing over.
It depends on avionics fit. Even in an aircraft with two tranponders, it may not be possible to set the code on the transponder not in use. Although you may have 2 tranponder boxes in the rack, often they are operated by a single control head. This would have a toggle switch to change between 1 and 2, but only one set of code setting knobs. Does that make sense?
I.E. you can't change the code on the box not in use.
If I can just reiterate for those who are clinging to the 'Standby' method, please don't do it. Even if your transponder is at standby for say 5 seconds that is still a large proportion of the alert time thresholds for TCAS at low levels. If you are really worried about inadvertantly selecting an emergency code, it pretty easy to avoid going via 77, 76, or 7500. You're much more likely to get caught out by the single push 'squawk emergency' or memory features that some control heads have.
CPB
regarding setting the code on the other transponder, and then changing over.
It depends on avionics fit. Even in an aircraft with two tranponders, it may not be possible to set the code on the transponder not in use. Although you may have 2 tranponder boxes in the rack, often they are operated by a single control head. This would have a toggle switch to change between 1 and 2, but only one set of code setting knobs. Does that make sense?
I.E. you can't change the code on the box not in use.
If I can just reiterate for those who are clinging to the 'Standby' method, please don't do it. Even if your transponder is at standby for say 5 seconds that is still a large proportion of the alert time thresholds for TCAS at low levels. If you are really worried about inadvertantly selecting an emergency code, it pretty easy to avoid going via 77, 76, or 7500. You're much more likely to get caught out by the single push 'squawk emergency' or memory features that some control heads have.
CPB
Guest
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What are you talking about feather#3.....
Jurasic radar? old technique? You've obviously spent too much time in that glass cockpit that you fly.....try a bit of real flying in the real world. Oh, by the way, next time you are sitting at the controls of your 747, in between cups of coffee I would respectfully suggest you brush up on TCAS operations....which ONLY works on mode C interrogation.
Back to the real world.
I spoke to D&D at LATCC this morning who were pleased this subject has been mentioned as pilots who change squawk without going to standby mode are the bane of their lives. The chaps there were very helpfull and made three important points.
1. D&D (SAR) radar is no different from any other radar. Two hits will be required for capture.
2. ALLWAYS turn to standby when changing codes to avoid setting SAR alarms off, which happens on a regular basis due to pilots using the "Ausie" method of just changing the numbers.
3. When the SAR alarm is set off, that screen is then out of action untill the matter has been resolved thus creating a small delay should a real emergency code be transmitted.
They also mentioned that since 7000 was introduced they get far more erroneous alarms as two aircraft changing to 7000 without going to standby in close proximity can trigger the alarm. Apparantly this is quite common around the Solent area.
They informed me that there is talk of reverting back to the old 4321 conspicuity code.
It may be helpfull to draw a line between GA traffic pottering about VFR and airways traffic who will not be squawking 7000. It is the GA traffic that can cause a problem when changing without reverting to standby.
D&D are now aware of this site and may well talk to us in more detail if requested.
[This message has been edited by Flybywyre (edited 05 May 2000).]
Jurasic radar? old technique? You've obviously spent too much time in that glass cockpit that you fly.....try a bit of real flying in the real world. Oh, by the way, next time you are sitting at the controls of your 747, in between cups of coffee I would respectfully suggest you brush up on TCAS operations....which ONLY works on mode C interrogation.
Back to the real world.
I spoke to D&D at LATCC this morning who were pleased this subject has been mentioned as pilots who change squawk without going to standby mode are the bane of their lives. The chaps there were very helpfull and made three important points.
1. D&D (SAR) radar is no different from any other radar. Two hits will be required for capture.
2. ALLWAYS turn to standby when changing codes to avoid setting SAR alarms off, which happens on a regular basis due to pilots using the "Ausie" method of just changing the numbers.
3. When the SAR alarm is set off, that screen is then out of action untill the matter has been resolved thus creating a small delay should a real emergency code be transmitted.
They also mentioned that since 7000 was introduced they get far more erroneous alarms as two aircraft changing to 7000 without going to standby in close proximity can trigger the alarm. Apparantly this is quite common around the Solent area.
They informed me that there is talk of reverting back to the old 4321 conspicuity code.
It may be helpfull to draw a line between GA traffic pottering about VFR and airways traffic who will not be squawking 7000. It is the GA traffic that can cause a problem when changing without reverting to standby.
D&D are now aware of this site and may well talk to us in more detail if requested.
[This message has been edited by Flybywyre (edited 05 May 2000).]