Mayday, radio silence and CAS

[bjornhall]

What are you supposed to do if there is distress traffic on your frequency when you need to make a call that is normally mandatory? For example when approaching your clearance limit or reaching a mandatory reporting point?

In many situations it is obvious (if you can remain clear of CAS until the distress traffic has ended then do so etc), but sometimes it's not: What if you are cleared to a point inside controlled airspace and reach that point? What if you are reaching a TMA sector border where you are supposed to call up the next sector; can you do that without telling the first sector that you are leaving their frequency? Or if you are leaving a CTR into uncontrolled airspace; do you skip the mandatory position report over the CTR exit point?

[tmmorris]

If you have an IFR clearance to a point then you go to that point and hold until you can contact someone for further clearance. If the Mayday is prolonged you may well be given another frequency to contact anyway ('All non-mayday traffic contact XXX on YYY' or something similar).

To the other questions, common sense suggests:

Crossing a TMA sector border, change frequency and advise the new frequency that you didn't sign out with the last one and why.

Departing a CTR into the FIR, just get on with it. They will have radar anyway and will see you have gone.

With any luck an ATCO will be along to explain in a mo...

Tim

[Fuji Abound]

I would only add that it is usually the Mayday traffic that is moved to a discrete frequency as soon as possible which, if you think about it, makes a great deal of sense given those coming on frequency may have no idea a Mayday is in progress.

[Timothy]

Speaking as someone to whom this happened yesterday (engine failure while in communication with Thames Radar) I was not moved to a different frequency and indeed they checked with me that I was able to change to TWR, giving the impression that they would have relayed all the way to the threshold if necessary.

In fact I could have coped with being moved to a discrete frequency because it was CAVOK and I had my act together, but I do not think that it is a clever idea in a single crew, distress environment.

I think that the answer is that radio silence is radio silence and that you only transmit if you really need to. Otherwise you continue with your clearance while trying to contact another ground station on box 2.

[Fuji Abound]

Timothy

I agree, I dont believe the Controller should offer the move unless it is clear the pilot is able to accept a frequency change. On the last two occasions I have had an in flight shut down a frequency change was offered and accepted as it was not an issue. I suspect where a change can be accepted it helps all concerned. As I commented earlier when people first pitch up on frequency they will have no idea a Mayday is in progress. Moreover on a busy frequency with a high volume of IFR traffic it must make sense to continue to handle the existing and new traffic on the published frequency and give the mayday traffic the dedicated service they might need. Still I dont really know what I am talking about, only my limited expereince as a pilot, it will be interesting to hear what those in the know from the AT side of the fence have to say about the decision making process.

[bjornhall]

That radio silence will be observed is hopefully a given! I was wondering if there is some procedure or practice to follow in such a situation that I wasn't aware of, apart from keeping one's mouth shut unless spoken to (which would be an exception, I should hope)... But if it's all down to common sense there shouldn't be a problem! :ok:

[HEATHROW DIRECTOR]

Definitely not a good idea to change frequency in busy airspace, otherwise the controller might want to urgently contact you and won't know where you are or who you are talking to. That particular situation has frightened me far more than the Maydays I've been involved in.

[bjornhall]

HD, I suppose you mean in case we are still in your airspace? Because if we leave your airspace there is probably somebody else we should be talking to instead, and you don't want us to just hang around at the CTR border until we can say our proper ICAO-style goodbyes, right? :)

[IO540]

If you have an IFR clearance to a point then you go to that point and hold until you can contact someone for further clearanceThat one is an interesting Q. Are there any rules for the case of "lost comms due to being unable to get a word in edgeways"?

The procedure, ICAO, for lost comms under IFR is to exhaust any explicit current clearance and then revert to the filed route, fly it, and land at the filed time.

There are national variations on this but that is the basic idea. There is an implicit clearance all the way to destination (well, in the civilised world, anyway).

If the IFR clearance is the "UK style Class D/G IFR" e.g. "cleared to SAM at 4000ft" kind of thing then that is still IFR, but somehow I doubt Solent would be banking on this eventuality, and very importantly they don't know your filed route because even if you filed a flight plan they will have never seen it (unless you filed Southampton as the destination or the alternate). In that case I would continue either the heading if assigned or the route if notified or otherwise obvious.

Not sure what happens if this happens on a VFR clearance in CAS. I'd continue as above. Doing a u-turn is not likely to help.

Not being able to get a word in edgeways is a major problem. It doesn't allow one to assume a clearance but once cleared to enter CAS you have to get on with it. ATC can do their job if there is a conflict.

[bjornhall]

Not being able to get a word in edgeways is a major problem.

Agree with much of the rest, so just to pick the bit I don't agree with then... ;)

In the real world, ATC would work the rest of the traffic, despite the emergency, so I believe it's unlikely that they'd abandon us at our clearance limit... Whether IFR or controlled VFR.

But in the hypothetical case when they do, I'm unsure how to deal with it, and I don't like being unsure. Even if the question is admittedly somewhat academical.

Does radio silence imposed by distress traffic on the frequency is really count as a lost comms situation? :confused:

[BackPacker]

Mods, can we move this thread to the ATC forums, or can someone otherwise start a thread there with the same question? I think that's the place where the expertise to answer this question is to be found, or at the very least an answer to what ATC expects you to do.

For IFR and for VFR OCAS the answer is quite clear (with a possible exception for UK-style IFR 'outside the system'). But if you're VFR inside controlled airspace (most likely a CTR) and your clearance limit is not the edge of the CTR (when departing) or the runway (cleared to land) but some VRP, are you expected to hold there, and if so, for how long? Do you eventually depart the zone via the shortest route without cutting through an ILS area, as if you're following no-comms procedures? And if you're cleared to enter the circuit, do you extend downwind until you reach the zone, do you hold on downwind, or do you overfly the runway at circuit altitude?

[HEATHROW DIRECTOR]

bjornhall wrote: HD, I suppose you mean in case we are still in your airspace? Because if we leave your airspace there is probably somebody else we should be talking to instead, and you don't want us to just hang around at the CTR border until we can say our proper ICAO-style goodbyes, right?

No.. But good communication procedures demand that you don't simply wander off frequency without saying so. In all my time as a controller I never experienced a situation - major emergencies included - where there was not time for a pilot to say he wanted to changing frequency when leaving my area of responsibility.

However, I've experienced a good few pilots changing frequency without saying anything and causing all manner of problems - some quite serious.. One I recall had flown SVFR through a control zone and simply QSYd as he left without saying anything...... head-on to opposite direction traffic which I was unable to warn him about. The subsequent avoiding action both pilots took was really quite amusing to watch on radar, even if it did give me grey hairs.

[IO540]

IMHO, any DIY activity in CAS is going to be worse than doing what ATC were reasonably expecting you to do.

For example if you are 10nm inside CAS and an emergency is declared, then I would continue on the current track, not e.g. do a u-turn.

[bjornhall]

No.. But good communication procedures demand that you don't simply wander off frequency without saying so. In all my time as a controller I never experienced a situation - major emergencies included - where there was not time for a pilot to say he wanted to changing frequency when leaving my area of responsibility.

Right! But as far as I understand, if there is distress traffic on the frequency I'm not allowed to talk on the radio, no matter how much I want to or how good an idea I think it would be (unless rendering assistence, responding to a call from the station leading the distress traffic, i.e. you, or being in an emergency myself).

You can talk to me, but I can't talk to you except to reply to you calling me, right? You can use a silent moment to speak with other aircraft if you're the station leading the distress traffic, but I can't do that no matter how quiet it is until the distress traffic has ended. If it was a PAN, I could speak up as long as I'm not disturbing the urgency traffic, but Mayday means radio silence, as far as I'm aware.

But Timothy gave what I think is the best solution: Keep monitoring the original frequency, and if I reach a point where I need to be talking to someone, call them up on a different frequency using the other radio.

[dublinpilot]

But as far as I understand, if there is distress traffic on the frequency I'm not allowed to talk on the radio, no matter how much I want to or how good an idea I think it would be
That is not correct. There is nothing that stops you speak on the frequency other than good airmanships whould would dictate that you don't make unnecessary calls.

Personally I would sign off on the frequency with as little fuss as possible. The last thing I want is the controller getting distracted from the emergency wondering what happened to me, or making blind calls to me to change frequency after I've already left unannounced.

dp

[bjornhall]

That is not correct. There is nothing that stops you speak on the frequency other than good airmanships whould would dictate that you don't make unnecessary calls.
No, the regulations impose mandatory radio silence while distress traffic is ongoing. Urgency traffic should be handled the way you suggest (do not interfere, but radio silence is not mandatory).

I checked the CAP in the unlikely event it is done otherwise in the UK (when did that ever happen? :E), but CAP 413 Ch. 8 sec. 1.10.1 seems pretty crystal to me. I'd be astonished if Ireland is any different...

[englishal]

But as far as I understand, if there is distress traffic on the frequency I'm not allowed to talk on the radio, no matter how much I want to or how good an idea
Impossible in some instances. I can vividly recall a trip to Stanstead one evening where talking to London Control, if you just had to maintain radio silence there would be pandamonium.

I reckon what would happen is that previous sectors would start allocating new frequencies to new traffic and start to switch existing traffic onto a new freq so eventually the original frequency would be empty. This is purely me guessing, but it would sort of make sense in a busy area.

Still if you are flying with modern avionics like the G1000, you just hold in the freq flip button and it tunes to 121.5 after a few seconds so not too big a deal to change frequency I'd have thought.