Ident on the ground?

[malcolmf]

Any ATCO in the tower at LHR is probably well aware of the difficulties BA have in getting an aircraft ready to fly in a timely manner. We are doing our best with getting briefings done as early as possible, but currently when we are transferred to TWR we are asked to "monitor". I usually disregard this and call fully ready when we are. Would squawking ident work on the ground and be any use? Woul it be a pain at Swanwick?
Just a thought so don't be too harsh on me

[HEATHROW DIRECTOR]

Full marks on the R/T side malcolmf... I pretty sure I know what the current people are going to say..... but I always viewed "monitor....." as appalling radio communication practice and never used it. It's never so busy that a single call "Speedbird 123" would cause problems and at least one would know that communication had been confirmed. I sat next to a young controller one day who rebuked a pilot for calling him first even though he was the only aircraft on the frequency. I cringed under my seat..

At one stage there was the suggestion that landing aircraft should be told "monitor the tower on...." which, IMHO, is an accident waiting to happen. Problem is that a lot of these clever ideas come from people with little experience of radio comms.. they think it's like a telephone call. Maybe it is, but there are a thousand numnbers you might accidentally connect to!!

HD (ex Heathrow Tower ATCO).... now awaiting flames.

[Radarspod]

Squawk Ident on the ground will not have any effect on Swanwick, as a transponder should not be replying to SSR or Mode S all-call interrogations when on the ground(*). As such, none of the Heathrow radars can see aircraft when they are on the stand and taxiing around the airport. There is no way therefore that a squawk ident done on the ground will have an effect at Swanwick, unless the aircraft has a fault and is replying when it shouldn't and the Heathrow ER radar is providing an SSR track - but even then I would imagine some airport filtering is applied at the centre.

The only affected user would be the Heathrow Tower which is using multilateration as part of the A-SMGSC and a squawk ident could be detected by multilat system from Mode S squitter and roll-call replies that are permitted when on the ground.


*Just to clarify, not all aircraft have this capability. It requires a weight-on-wheels type switch mechanism to determine the aircraft state. Smaller airframes and rotorcraft are likely not be be equipped, and rely on pilot action to put the transponder in a state to reply. However, from vast majority of EGLL traffic, switch mechanism will automate the transponder response state.

[Dan Dare]

While I agree with HD that "monitor" on transfer from radar to tower is a very bad idea, I have never seen a problem with it for the queue of aircraft awaiting departure. I sometimes wonder what part of "monitor" pilots don't understand, when there are 10 aircraft ahead of them, a steady stream of inbounds and someone over the fence awaiting landing cearance, which comes even later because you want to put your towel down. And given the scenario above, I would be astounded if you were not ready when your turn came. While you are waiting, I should think you establish that you are actually monitoring the correct frequency, so it is rare that a monitoring aircraft in the queue is not listening when his turn comes.

If traffic levels are low and you are taxiing towards the hold with nobody else there, then by all means tell us that you are ready (and that you could depart from intersection xxx), but we are likely to be ahead of you there and to have asked you to report ready if we are going to be able to make use of you. We want to make most use of the runway (delays are hard work), so believe me you will be airborne as soon as we can possibly get you there.

As for squawking ident on the ground to signify ready - nice idea, but I'm not sure it would be of benefit - If ASMGCS (ground radar) was able to show your ident it only shows for seconds, so I don't even think the departure controller would even necessarily notice, when they are looking out from the visual control room. Notwithstanding BAs difficulties, we would normally expect you to be ready at the hold when you are number one and if experience tells us that you may not be ready we would ask you to report when you are. [/Ramble]

[Gonzo]

'Monitor' is a very good idea to use for a queue of departures. There are few things more off-putting than pummeling those brain cells trying to figure out how you're going to cope with the BPK+4 MDI that's just been slapped on, as well as how you're going to get those two late slots through the crowd and airborne in time and then hearing 'Tower, Fastair123' when you're not expecting it. Ok, so now you need to reply...you wonder what the matter is....'Fastair123'...........'Tower, Fastair123 is holding at S1N'

I can see that, thank you. Now, where was I?

Please, if you're told to monitor, then monitor.

I would recommend, once you're given marshalling instructions past PLUTO/ETTIV/HORKA etc, is to tell is if you're not ready when reading them back. That gives us a chance to do something with you.

[5milesbaby]

Radarspod - if an a/c is fully ready for departure then I imagine that the SSR interrogation will have been turned on as part of the departure checks (doubt very much it happens just after rotation). Unfortunately LHR has a couple of taxiways that are high enough for a/c to give a good signal to the Swanwick radars and occasionally (although not regular) are caught. For those that don't know this activates the flight in the centre computer and produces times and details to the radar controllers which are wrong as its a false activation. I would say personally last year this happenned 4 times, normally a heavy jet taxiing out of Terminal 4. So squalking IDENT could affect the Swanwick system.

[Dream Land]

When your in a queue of over fifteen or more it's hardly necessary to inform tower of anything until you are number one.

'Monitor' is a very good idea to use for a queue of departures. There are few things more off-putting than pummeling those brain cells trying to figure out how you're going to cope with the BPK+4 MDI that's just been slapped on, as well as how you're going to get those two late slots through the crowd and airborne in time and then hearing 'Tower, Fastair123' when you're not expecting it. Ok, so now you need to reply...you wonder what the matter is....'Fastair123'...........'Tower, Fastair123 is holding at S1N'

I can see that, thank you. Now, where was I?

Please, if you're told to monitor, then monitor

[Radarspod]

if an aircraft is providing responce to SSR interogations on the ground, then it is operating incorrectly. The pilot will move the transponder from standby to an operational state (can't remember the switch settings, something like active or tx/rx or suchlike) at some time either at the gate or on pushback, the transponder is now prepared to reply. But until it takes of and the suppression signal from the wow switch is removed, the transponder will not respond to Mode A/C interrogations or Mode S all-call. If they did, the two radars at Heathrow will be tracking all of the aircraft around the airfield, which would cause all kindsof problems. The aircraft should only be appearing on the ATM displays at EGLL and to any other radar users once the aircraft is airborne (Mulitlat feeding ASMGCS is different)

If some SSR tracks are getting through to H23 or H10 radars and sent to Swanwick, this is only because of faulty aircraft transponder suppression, not normality.

I'm currently sitting in the Eurocae working group that defines the MOPS for transponders, and we happened to discuss this very subject this morning!

[HEATHROW DIRECTOR]

<<'Monitor' is a very good idea to use for a queue of departures. There are few things more off-putting than pummeling those brain cells trying to figure out how you're going to cope with the BPK+4 MDI that's just been slapped on, as well as how you're going to get those two late slots through the crowd and airborne in time and then hearing 'Tower, Fastair123' when you're not expecting it. Ok, so now you need to reply...you wonder what the matter is....'Fastair123'...........'Tower, Fastair123 is holding at S1N'>>

Don't make it sound difficult for the punters Gonzo when it's really a doddle! I recall doing 51 deps one hour and we didn't use "monitor" in those days!!! Tee hee hee!!

[Gonzo]

It would have been even easier with 'monitor'!!!

By all means come and have a go with our electronic strips and only one conditional clearance!

[Eric T Cartman]

Oh no ! Now I have this image stuck in my head of Gonzo sitting in EGLL VCR wearing a Millwall scarf chanting "come an' 'ave a go if you fink yer 'ard enuf!"

[Gonzo]

One believes Millwall plays Association Football, the ruffians' game. One is more cultured than that.

[Point Seven]

Don't think squawk ident works on A-SMGCS without a software upgrade.

P7

[GTH]

The software's not the problem, P7. The multilateration is basically a passive system relying on squitters that aircraft automatically broadcast, with infrequent interrogations for Mode A. The squawk ident sets a bit in the Mode A message, not the squitter, and it only sets it for 18 seconds. Therefore it is possible that the squawk ident would appear between interrogations, so the system would miss it.

[Dunregulatin]

Could it be that Malcolmf knows his phraseology? Actually, obviously not but he has a point - "monitor" is incorrect phraseology. The correct phraseology is "standby for (....) on (freq). MATS 1 section E attach refers. But of course that's too many words for busy Ground controllers!

[Gonzo]

We tried that when it first came in. Didn't work. Went back to 'monitor' as per Part 2.

SRG aware.

[llanfairpg]

I sat next to a young controller one day who rebuked a pilot for calling him first even though he was the only aircraft on the frequency. I cringed under my seat..

Not as much as I did when my FO on his flight out of LHR chaged frequency and said.

"Monitor this is XXXXXX!"

[criss]

"Any ATCO in the tower at LHR is probably well aware of the difficulties BA have in getting an aircraft ready to fly in a timely manner."

In fact its "Any ATCO in the tower", not only LHR.

[malcolmf]

I knew it would open up a can of worms!!

And given the scenario above, I would be astounded if you were not ready when your turn came

Believe it or not it happens!!
All I'm trying to do is help the controllers, at the moment, particularly on departures from T4 to 27L and T1 to 27R/L there is a very short taxi (for a 744) and I a) don't want to get stuck in a sin bin or b) block taxiways.
We are well aware of the time it takes and the more proactive of us get the briefings done on stand if we've got a stand hold, but we can still be waiting for final figures for a multitude of reasons.
I guess the pragmatic thing is to call if we think we may not be ready, but not too late so we block the holding point. As long as you guys are assuming we will be ready
It'll all be OK at T5
Thanks for the input.

[RadarRambler]

transponders on the ground at some units actually cause problems, not all units have the A-SMGCS, so ident would in factat some units cause even more problems.