I have a theory that Brussels only knows of four enroute points in their FIR: KOK, COA, BUB and LNO. Whatever you file, that tends to determine the routing.
On “resume own navigation to XXX”, I can’t think of a situation in which it would be safe for ATC to assume that you would not take a direct route to XXX. ATC has to look after terrain etc. until you’re back established on the ATS route, and I don’t see how they can be sure where your track will rejoin the ATS route if it does so before XXX. So I think it tends to be used after radar vectors, while “direct to XXX” tends to be used when you’re navigating to a different point.
bookworm wrote:
ATC has to look after terrain
Personally – and maybe that this is because I started IFR with a UK IMC rating, where you are pretty much on your own most of the time, I think of ATC as a service designed to keep me away from other aircraft, while keeping away from terrain is my job. And so is making it to my destination. So while ATC has to make sure they do not issue instructions that put me in conflict with terrain, it is still my responsibility.
Hardly a factor en-route in Belgium, where the highest point is below 2,300ft… :-)
I understand it to mean I am no longer being vectored and am responsible for navigation. I don’t take it to mean direct. If I was cleared on an airway and then received vectors for traffic or weather, I would expect to rejoin the airway. If I was VFR, then I am in charge of my route and take whatever routing I choose.
Cobalt wrote:
So while ATC has to make sure they do not issue instructions that put me in conflict with terrain, it is still my responsibility.
It’s also your responsibility in all conditions to avoid collisions with other aircraft. However, in some circumstances (class A/B/C airspace under IFR), the primary responsibility for that is ATC’s. Similarly when being radar vectored or giving a direct clearance, the primary responsibility for assigning a terrain-safe level is ATC’s. Always good to double check though.
The only time ATC has responsibility for terrain clearance is while issuing radar vectors. At any other time the pilot is responsible. So if I have filed GTQ – PHALO – Colmar, and at GTQ and FL100 I am cleared to descend for the approach to Colmar (as has happened to me) it is my responsibility to avoid flying into the Vosges by checking the MSA on the approach plate, not just dive and drive to the 3300 platform altitude or the 4700 hold altitude. So I wouldn’t assume that ATS has to look after terrain. In the enroute context of the OP question this is probably less relevant, but worth calling out all the same.
Cobalt wrote:
Other examples include a clearance to a waypoint not on, but close to the original route. When around FL100-150 on L607 (KONAN-KOK-MAK-LNO), Brussels often clears me to Brussels (BUB) which is a couple of miles to the side, and they NEVER tell me where to go next. So when reaching BUG, I always just say “G-XXXX, at Brussels, proceeding direct Olno”, which always elicits a “roger”.
I would reply that waypoint is not on my flight plan, confirm BUB and request further routing.
Rich wrote:
The only time ATC has responsibility for terrain clearance is while issuing radar vectors. At any other time the pilot is responsible. So if I have filed GTQ – PHALO – Colmar, and at GTQ and FL100 I am cleared to descend for the approach to Colmar (as has happened to me) it is my responsibility to avoid flying into the Vosges by checking the MSA on the approach plate, not just dive and drive to the 3300 platform altitude or the 4700 hold altitude. So I wouldn’t assume that ATS has to look after terrain. In the enroute context of the OP question this is probably less relevant, but worth calling out all the same.You are quite right, but even professional pilots are not always aware of this.
No. it’s simply not correct. In PANS-ATM:
8.6.5.2 When vectoring an IFR flight and when giving an IFR flight a direct routing which takes the aircraft off an ATS route, the controller shall issue clearances such that the prescribed obstacle clearance will exist at all times until the aircraft reaches the point where the pilot will resume own navigation. When necessary, the relevant minimum vectoring altitude shall include a correction for low temperature effect.
A direct routing which takes the aircraft off an ATS route is equivalent to radar vectors in terms of ATC responsibility. Clearly the pilot should do all he can to ensure that levels flown are terrain safe, but that also applies when on an airway.
If you’ve filed a DCT segment outside controlled airspace, then it’s obviously your responsibility to fly a terrain-safe level, but you shouldn’t be getting a clearance for that.
bookworm wrote:
A direct routing which takes the aircraft off an ATS route is equivalent to radar vectors in terms of ATC responsibility. Clearly the pilot should do all he can to ensure that levels flown are terrain safe, but that also applies when on an airway.
That’s interesting! Do you know if that is a recent revision of the PANS-ATM text?
There is some self-contradiction in that paragraph. It says that the pilot will resume responsibility for obstacle clearance when resuming own navigation — but a direct routing is “own navigation” unless on radar vectors.
As with most ICAO stuff, the committee nature of the drafting process makes the wording sub-optimal.
I think it’s obvious that a controller-initiated direct routing has to be terrain-safe like a radar vector. We expect pilots to carry charts of airway MEAs, but not complete terrain databases, which simply haven’t been available up until a few years ago, and which would be necessary in order to evaluate a direct routing, just like a radar vector.
The report on HAZE 01 is interesting. The controller at Kiruna gave the aircraft an instruction to descend from FL100 to FL70 outside controlled airspace, when 70 was not terrain safe. I find the way the conclusion is worded quite bizarre:
The accident was caused by the crew on HAZE 01 not noticing the shortcomings in the clearances issued by the air traffic controllers and to the risks of following these clearances, which resulted in the aircraft coming to leave controlled airspace and be flown at an altitude that was lower than the surrounding terrain.
It is unusual for such a conclusion to focus on the “failure to notice” shortcomings in another party’s responsibility the system, rather than focusing on those shortcomings themselves! In reality, there are three actors who could have prevented the tragedy: the controllers, the crew themselves, and the ATM regulators and managers who left the roles and responsibilities unnecessarily ambiguous.
