MODE S Operation while airborne

[1999]

One short question for you "people in the best offices in the world" especially bus drivers ...

Are you able to reselect your MODE S identification during the flight? And how do you do it?( is it enough if you retype your Flight number in your FMS or there's other way to achieve this?)

Why do i ask?
Recently MODE S radar was implemented into the system at my unit. Although we still function and provide radar identification based on the "regular" Mode A method, from time to time we get a small warning mark next to certain flights whos MODE S identification doesn't correspond to that in their current flight plans. During the low traffic periods I sometimes check with pilots of such "erroneous" Mode S settings to "RE-ENTER MODE -S AIRCRAFT IDENTIFICATION" ..which is an ICAO published phrase for such occurences. The responses from pilots are sometimes awkward ...from .. we can't do that ... to some who clearly don't even understand what I'm asking ... If time permits I try to explain in plain language what I would like them to do ..that is.. to put the correct Flight number into whatever box they should ...lol
And there that myth arose somehow ..that airbuses and certain types of A/C are not able to do that while airborne...
So I would like to get the firsthand clarification from you guys :)

Regards from the green radar pastures bellow :)

[flyburg]

Never having done so but it would only entail changing the flight code on the route page in the FMS. Don't know if you can do that inflight but see no reason why not.

Fly boeings

Below an excerpt from the manual about entry of flight number on the FMS route page, no mention that this cannot be done inflight.

6 Flight Number (FLT NO)

Valid entry is any flight crew entered flight number. The FMC sends flight number to each ATC transponder for flight ID function.

Flight crew entered or uplinked.

Flight number displays in PROGRESS page title.

Data line blanks at flight completion.

Transponder transmits flight number to ATC when Eurocontrol-compliant transponder installed.

[1999]

Flyburg , thanx for your reply ... I was asking myself the same question - why on earth and at this stage of technology one would not be able to type a few letters and numbers ...
One thing in particular I've noticed on the subject mentioned - the most usual mishaps are A/C Flight numbers from the previous flight. I would assume when you download your FPL via ACARS such errors couldn't happen presumably the A/C Fl.No. would be correct there ?

"If It ain't Boeing, I ain't going" LOL :)

Thanx for your input my friend.
Tot ziens :)

[Capt Scribble]

Airbus FMS2 now allows a simple amendment to the callsign, previously you would have to reinitialize the flight through the secondary flight plan. Maybe some did not know how to do this.

[fivegreenlight]

on 737 it seems to depend on the transponder fit, some you enter it in the FMC and some need it entered into the transponder. Some transponders don't have the facility ie only sqk input.
Have been asked to change it airborne as forgot to change it from previous sector ! but used txpdr input to do it.

[1999]

Uhhmmm ... Capt Scribble, now that explains it all .. so obviously there were really some limitations in that regard.

We are all prone to "forget" or not being comfortable with certain things we don't use often ... MODE S resetting is obviously one of them.
If some who check out this thread get reminded how to do it, we did a good thing with this discussion . :8


Thanx for your input guys. :ok:

[hapzim]

It's a shame that when you put your flight number in the FMS that it does not also display said flight number on the ND display for all the flight. I might be able to remember my flight number for the day then.

[flyburg]

Don't have the ability to download the flight plan on my aircraft, but what would occasionally happen is that we would have a different flight number and callsign.

For example in Europe to avoid similar callsign Confusion and for some reason lately to the states. Crews would inadvertently input the flight number in the FMS instead of the ATC callsign. In Europe for example klm1237 instead of klm37D, or something along those lines. Both are given on the flight plan but if you are in a rush, easy to overlook!

Tot ziens.

[FLEXPWR]

hapzim

the flight number on ND would be nice indeed, but it is displayed in FPLN page on the top line, it is also available in numerous other menus, and the PROG page as well as submenu "report".

Personaly, I just look at the top of FPLN page when making or receiving a call, however, it is not displayed there if you have an offset. So just press the PROG page.

[sleeper]

I must be getting old.
I make a fairly large note of my current callsign and clip that on the yoke.
Works like magic. :)

[1999]

Sleeper ... hahaha .. that's pure analog vs. digital technology baby :)

[Clandestino]

previously you would have to reinitialize the flight through the secondary flight planI used to ride RHS on early 90s vintage 320 where even that workaround was not available and there was no way to change wrong C/S once at least one engine was running. As you mentioned, it is corrected in FMGS version 2. In version 1, depending on software version, you have to find your way around it or live with wrong S mode callsign until engines are shutdown.

My current steed (Q400) has Universal FMS which allows trouble-free change of callsign in any phase of the flight, which comes pretty handy when Langen or Munich ATCOs diligently point out someone has made a typo during preflight FMS preparation.

[Shore Guy]

A possibility....if the aircraft is transmitting an ADS-B "out" signal, there is a possibility that the call sign is different than the one programmed into the FMS. In transport aircraft, the ADS-B information is normally transmitted through Mode S. It can be transmitted through other data links.

Do you know...does your display have a priority to display ADS-B call sign vs. the "normal" Mode S/FMC call sign?

[Flaymy]

The most common retrofit on smaller GA aircraft is the Garmin (GTX330 I think) which as far as I have found needs to be turned off and back on again to change the flight ID. I have done so a couple of times, after warning the ATSU that I will stop squawking for a minute or two.

[Jetjock330]

Yes, it can be reset in-flight A346. We got airborne one night from SYD and immediately, for various reasons had to do a tech stop into SIN and was given a revised FLT number to entered with a "B" attached.

We then changed the FLT number in the MCDU thru the ACARS if I can remember, or on the secondary and activated it. But either way it can be changed! Although it was a while back.

Can be changed in the B777 in-flight too.

[DaveReidUK]

It's not uncommon, on occasions when an incorrect Mode S flight ID has been set on an eastbound LHR departure, to see it being corrected when the aircraft gets to the FIR boundary and starts to talk to Maastricht.

Seems to happen on both Boeings and Airbuses.

[Jetjock330]

If the flight number is wrong, it won't log on to Maastricht, EDYY if I remember (HELP, I may have the log on wrong too!)

[1999]

Shore guy .. if you ask me abouth those details.. unfortunately I don't have such an in-depth knowledge ...that's more in the field of technicians expertise ... :)
I'm just a poor sod sitting in front of the radar screen somewhere in Europe. But as I mentioned earlier according to my experiance the majority of the erroneous indications are plain and simple typos ...e.g. AF1234 instead of AFR1234 (i'm using this just as an example not pointing blame on a given airliner) , and "left over" flight numbers from the previous sectors.

[EEngr]

1999, during what phase of flights are you seeing these errors? And what are the consequences of having an incorrect ID?

It might be one thing to spot this if the flight is en route and the crew has some time to fix the data error. But if its on approach, they might be a bit too busy to figure out a little used procedure.

By 'consequences', I'm also wondering what affect this kind of error might have on other systems like TCAS, ADS-B, etc.

[Denti]

There should be no effect whatsoever on TCAS, on ADS-B/C of course the wrong ID is transmitted which might lead to problems.

As europe is moving slowly to radar allocation via Mode-S ID a very low failure rate is becoming more and more important. Currently Mode-S ID allocation with a blank 2000 squawk is used only on dedicated routes, however the number of routes is slowly increasing and in the end most of europe should work that way.

At the moment my outfit gets a letter each month with every wrongly entered Mode-S ID, however we are below the magic 1% for quite some time now, but still trying to improve that figure of course.

[Intruder]

Are you able to reselect your MODE S identification during the flight? And how do you do it?( is it enough if you retype your Flight number in your FMS or there's other way to achieve this?)
In the 744, yes. It is controlled by the call sign entered in the ACARS Preflight Initial Data page. Found out for sure today when I fat-fingered it on the ground, and Frankfurt Departure immediately didn't like it...

[Denti]

As posted above on the 737 it depends on variant and transponder retrofit. On the classic we had some retrofits where the ID had to be entered into the transponder directy. On others we had the same method we use on NGs, the ID is entered into route page 1. Both methods allow easy change inflight.

ATC callsigns are usually different than the commercial flight number, therefore we always check out the callsign info on our LIDO flight plan or on our crew briefing sheet, not the flight number.

[1999]

EEngr, I'm spotting it and dealing with it when they are at their cruising levels ...of course i wouldn't bother them during climb or descend preparations ... :)

I would say there are no immediate consequences on other systems ... although in certain situations the correct mode s id setting would become handy ... if for example our data processing system on ground crashes for one reason or another(it happened a few times) the first consequence is that all the correlation on the radar screens is lost ... meanning .. i won't see a callsign next to your aircraft bleep but only Squawk A figures for all the flights except those who have Mode S(they would retain corresponding callsings) ... if there were a lot of aicraft in the sector at such times retaining identification is more time consuming compared to the one when system authomatically correlates flights displaying their callsings next to little dots on the screen :)
The second reason I question the pilots of such flights is : if that ident feature of Mode S is there for a reason, then it should be correct . Its the foremost for their own safety sake and my peace of mind as well.
Chain of events is a curious thing, often leading to disasters - and you never know when such feature is going to take a part in an incident or thus preventing one.

Fly safe http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/infopop/icons/icon6.gif

1999

[EEngr]

Thanks 1999.

I'm approaching this problem not as a professional pilot, but as an engineer who is often involved in issues of man-machine interfaces, usability, etc. We're the people who hide all those important functions in obscure menus and make you reboot your Windows PC every time you change some trivial parameter. :O