In the UK, if vectored off my flight-planned route, either with a waypoint (also off flight-planned route) or on a heading and I then suffer total comms failure, what will I be expected to do?
It's an interesting reflection on the difference in UK and US attitudes to IFR clearances that an instrument rated pilot would ask such a question. And I mean that as absolutely no criticism of Captain Stable, but as a comment on the relative importance attached to the concept of a
clearance in the two environments. My impression is that the ICAO expectation is much closer to the US rigorous approach and that the UK ATC system is going to get bitten in the
one of these days. It is also perhaps a reflection of the fact that true irreversible comm failure is a rare event in the UK environment because of the average quality of the equipment flying in it.
In principle, you're in one of two states: you're flying your clearance, which takes you on an unambiguously agreed route to destination, or you're on a vector, a temporary deviation from that clearance. The comm fail procedure if you're on a vector is laid out in the AIP -- stay on the heading for 3 mins after squawking 7600 and then resume your clearance.
The situation of being sent ("cleared"?) to an intermediate waypoint which is not on your cleared route should not arise -- you then have a
broken clearance because it doesn't take you to your destination. Again, in principle, when sent to a waypoint that is not on your cleared route, you should be refusing the reclearance until you have a route that you can fly unambiguously to your destination.
Most of the time, it doesn't matter, because the radio hasn't failed and you either get another instruction or you can ask ATC "where to next then?" But there's the potential for something nasty to happen when an aircraft has accepted an instruction to an off-route waypoint, the radio fails and it's not clear what the aircraft should do next.
A similar situation may arise because UK ATC is not in the habit of telling aircraft where vectoring will end. Here's what
Order 7110.65P (equivalent of MATS) 5-6-2 says:
b. When initiating a vector, advise the pilot of the purpose.
PHRASEOLOGY-
VECTOR TO (fix or airway).
VECTOR TO INTERCEPT (name of NAVAID) (specified) RADIAL.
VECTOR FOR SPACING.
VECTOR TO FINAL APPROACH COURSE,
Note that "VECTOR BECAUSE I JUST WANT YOU ON THAT VECTOR AND WE WON'T WORRY ABOUT WHERE YOU PICK UP YOUR CLEARANCE AGAIN" is not on the list.
Section 4-2-5 of the same document covers route amendments, BTW.
a. Amend route of flight in a previously issued clearance by one of the following:
1. State which portion of the route is being amended and then state the amendment.
PHRASEOLOGY-
CHANGE (portion of route) TO READ (new portion of route).
2. State the amendment to the route and then state that the rest of the route is unchanged.
PHRASEOLOGY-
(Amendment to route), REST OF ROUTE UNCHANGED.
3. Issue a clearance "direct" to a point on the previously issued route.
PHRASEOLOGY-
CLEARED DIRECT (fix).
NOTE-
Clearances authorizing "direct" to a point on a previously issued route do not require the phrase "rest of route unchanged." However, it must be understood where the previously cleared route is resumed. When necessary, "rest of route unchanged" may be used to clarify routing.
Note the clear underlying principle that there must be no doubt as to how the route is to continue.
Why doesn't UK ATC do it properly?