…on 2 Sep 2015 at 0953BST. Came up as an alarm on FR24, globally (but I’ve got the filters set-up properly on my phone, so it shouted-out).
I meant to post here about it on Wednedsay, but the day-job is currently crazy.
Hopefully was just a drill, or a only very minor tech issue. Unless someone here knows different…?
wilf_san
It happens regularly as part of training.
Probably a Practice Pan and D&D cell asking to squawk 7700 to get a fix.
I was unaware that they actually squawked 7700 during a Practice Pan. Yes, call on 243/121.5 for autotriangulation, but I thought there would’ve been a drill code?
This begs the question: under circumstances of COM failure (or sudden systems failure), how would a controller tell the difference between a real emergency or a drill one? Other than the absence of the ‘Practice’ prefixed message, I mean.
wilf_san
They don’t use any of the emergency codes in training. I have a leaflet somewhere from the D&D cell which is for pilots and explains it all inc the training opportunities.
CAP413 para 1.9.2 states:
If a practice is accepted, the pilot should then pass his details. SSR Code 7700 should not be selected during a practice emergency exercise unless required by the Emergency Controller. Mode C should be switched on, if available.
(I’ve actually been in the D&D cell when they asked a nimrod to squawk 7700 just so we could see what it did at their end, though that was a good few years ago.)
I concur; squawking 7700 is not actioned unless it is a real emergency. Very, very, occasionally, I have been asked to do so for 10 secs in order to do a gnd equipment check. Squawking 7700 lights up the ATC screens, & depending on the filters in use, can detract from monitoring other aircraft
Humm. Let me see if I can find that leaflet. It may be a general printed warning not to, but only if told to (but unprinted) iykwim.
There is an older document (CAP745) that outlines ATC actions & highlights what crews will be doing whilst they sort out an emergency.
CAP413 is the R/T authority for the UK (including the differences filed with ICAO )- you retain your original squawk unless instructed by the ATCC to squawk 7700:
If a pilot is already in communication with a civil or military ATSU, before the emergency arises, assistance should be requested from the controller on the frequency in use. In this case, any SSR code setting previously assigned by ATC (other than the Conspicuity Code 7000) should be retained until instructions are received to change the code setting.
Different countries may have alternative procedures that will be outlined in their national AIP.
It would have been a genuine emergency. Even though just about all Tutor ops take place under a radar service (and hence operate with a discreet SSR code) invariably during an emergency ATC will ask you sqk 7700 (it stands out on radar screens for a start.
Wilf: if you had a Com fail you wouldn’t be practicing any other emergency.
For practice emergencies, position fixing etc from D&D there is a dedicated UHF frequency known as Prectice Emergency Training Frequency (PETF). They will give a discreet SSR code if they need to and this wouldn’t be any of the genuine emergency codes.
If it was a genuine emergency then it is happening with alarming frequency. I’ve seen numerous reports on that Facebook group of tutors squawking 77’ .
I wouldn’t say that. Firstly things like FR24 make them more visible to the public, and secondly the emergency that the aircraft is squawking 7700 may actually be relatively minor.
Having had occasion to actually go with M we were not asked to squawk as we were already identified and receiving a service at the time and commed on Guard.
Along with the 6/5 numbers it’s part of the alternative comms package.
ISTR there was a tx plug in tester so you did not have to TX
I’ve known it all to kick off due to accidental sarbe activation. Embarrassing for the chap who’s flying kit locker was having an emergency!
It’s also embarrasing for the armourer who forgets to fit the blanking plocket to to the bang seat floor connection after removing the seat, prior to the aircraft being powered up. This has a similar effect to a sarbe activation. It was so funny for the riggers and fairies, less so for the armourers. 
Surely 7700 is a distress code along with a “Mayday” call meaning the aircraft “is in distress and requires immediate assistance”. A comms failure aircraft would squawk 7500. A “Pan” call is not a distress call and is only recognised in certain countries.
The other myth that I still hear is that you should turn transponders off when changing code in case you go through 7700. This hasn’t applied for many decades as the radar has a built in delay before it gets upset over a 7700 squawk.
A simple rhyme
Seventy five, taken alive (Hijack)
Seventy six, a box of tricks (Comms failure)
Seventy seven, going to heaven (Distress)
Comms fail is 7600…
A Mayday can still be something relatively minor, or not even a problem with the aircraft making the mayday call. Even a Pan aircraft may sqk 7700.
That is what I said.
Sort of. In your first paragraph you said 7500!
(I had tried to edit my response but the new forums aren’t as user friendly as the old one!)
Sorry, it was just a typo.