Mode C "test"???

[Blastoid]

I am curious to know whether some jet jockeys ever try to see whether a controller is paying attention by "accidentally" switching their Mode C off (e.g. in the cruise) to see how long it takes the controller to notice.

This occurred today, with the following exchange (after controller notices no mode C return from a RPT):

"ABC no mode C readout, request you recycle mode C"

(silence)
(Mode C returns)

"ABC thank you"

(silence) :rolleyes:

There was no operational significance to the occurrence, only to say that the lack of a response from the crew (e.g. oops I bumped it) led me to think that this was intentional.

Do professional RPT pilots really do this sort of thing as a joke or is it more likely they were too embarassed to own up to bumping it?

[edit for spelling :{ ]

[grrowler]

I guess whether it was a slipup or whether the system glitched doesn't matter, it wasn't really necessary to clog the airways with a "Ah roger, umm...bit embarassed by this... I went to slap the fo's hand away cos he was gonna touch something and I slipped and knocked the tx...oops sorry...ok you should be getting it now, I've turned it back on and we're getting a flash...we're passing 8500 by the way...HEY GET YOUR DIRTY HANDS OFF THAT!...oops still transmitting, sorry gotta go....":}

[Dehavillanddriver]

I can only think of one bloke that would do that - he isn't a professional pilot, though he does fly over vast amounts of water in single engined turbine power aeroplanes.


sings "Climb every mountain!!"

[Blastoid]

Thanks for the replies.

S-T - yes, it is a serious question. The lack of any acknowlegment (even a momentary TX as is common in such a situation) made me wonder about the scenario - I wouldn't post a beat up thread (although I know many do....) :ugh:

Dehavillanddriver

Is that the same one who is threatening to sue AsA? :yuk:

[grrowler]

What would turning mode c off achieve for the crew? I can't think of any pilot who would do it intentionally (obviously there are some as DHD pointed out). I have seen pilots occasionally hit ident to wake up a controller if they are approaching controlled airspace and haven't been given a clearance yet.

From the ATC's point of view, isn't the appearance of an alt on the screen an indication that the aircraft is back in mode c without a transmission to confirm it?

[Here to Help]

I have seen pilots occasionally hit ident to wake up a controller if they are approaching controlled airspace and haven't been given a clearance yet. I wonder why they wouldn't just transmit and ask for clearance. Squawking ident near a CTA boundary without being asked to can cause problems, especially if a controller is trying to identify another aircraft at the time.

[Roger Standby]

I like the idea of the pilot hitting his ident approaching cta. Although not by the books, if things aren't too busy, a subtle dig sends home the message. How many times have I repeatedly offered an airways clearance to an RPT twin turb. who fails to respond because they have taken off their headset having passed A100. Now they can wait 'til they're really approaching. It's subtle, it prevents chewing each other out over the radio and hopefully sends home the message. Mostly I think we all do a pretty good job and try and look after each other. Occaisionally frustration sets in but as long as we get over it quickly and get on with the job, I like a bit of creativity in a black and white world.

Also to grrowler, to ignore someone that has asked you a question is just plain rude- a simple callsign response would do.

Cheers,

R-S.

P.S. I await the vitriole

[SeldomFixit]

Mode C readout, like most digital streams, does occasionally forget to wake up. There is frequently another channel that can be selected to restore normal ops. By the time you get around to reselecting the initially faulty channel, it's usually ops normal again anyway. Such is the operation of a " glitch "

[Icebreaker]

Transponders and encoders fail on the occassion....more like he/she just selected no.2 after the ATC instruction. Would have expected an acknowledgement though. Of course an VHF R/T acknowledgement isn't required from an instruction to squawk ident.

[grrowler]

to ignore someone that has asked you a question is just plain rude- a simple callsign response would do.
Yep fair enough, and most crew probably would. It's hardly enough reason to accuse someone of intentionally turning your tx off as a joke (don't really see how it's funny).

Do professional RPT pilots really do this sort of thing as a joke No

or is it more likely they were too embarassed to own up to bumping it? Yes it is more likely, however more likely still are the scenarios from SF and icebreaker.

[boofta]

Dear Icebreaker.
Of all the things that need to be read back/acknowledged, a reply
with your full callsign to "Squark ident" is in my opinion one of the
most critical.
There are so many similar airline callsigns nowadays, all the Asian
carriers load up with 8's and 9's for good Fung Shui/luck that its too easy to be misidentified.
If there is one single instance of the wrong aeroplane squarking
ident without replying to ATC, then you are dead wrong my friend.

[Icebreaker]

Boofta,
You'd better tell that to ICAO/ASA/CASA then....cause it is not a response item (because you are doing so when you press the ident button) - refer AIP. In any case, SSR data tags are the double check.

[Blastoid]

Of course transponders can have problems ... normally though a crew would make a mention of changing to set #2 or "did it come back?" if they were not expecting that the Mode C would have dropped out. Also, the reply indicator on the transponder doesn't mean that all is well, mode A might be sending out the reply normally.

As for squawking ident to alert the controller that you're getting close to CTA .... interesting and I've never seen it before. Personally, I see quite a lot of idents not from intention but more from RADAR garbling, and I never take an unnanounced ident to mean anything unless I've to reason to suspect otherwise.

Besides, aren't you only supposed to ident if requested by the controller? (if you have other problems, there are other codes for that....) :hmm:

PS R-S no vitriol here (I hope), this isn't a NAS topic :ooh:

[Dehavillanddriver]

A lot of transponders don't have reply lights - the ones on the Boeings certainly don't...

[Roger Standby]

Geez DHD,

My c172 has a flashing light, therefore I thought all transponders did. Nice to know.

Cheers,

R-S.

[ITCZ]

146 txdrs do not show ssr 'hits.'

There are three indications that you have switched it on.... rotary switch position, console display says which txdr (1 or 2) is active, and the TCAS/VSI screen will annunciate TA or RA mode.

But no 'hits'.

Don't know what sort of goose would turn off their TCAS protection with the new airspace, just to give the controller a 'hint'..... seems pretty brainless.

More likely to believe that the thing has been accidentally left off, or the txdr 1/2 and tcas 1/2 toggles have been knocked to centre off by a meal tray.......