Peter wrote:
Interesting. I’ve never heard that in the European context – or indeed in the US context
Here is typical example from this AOPA article:
Prior to reaching the fix, our pilot is “cleared for the approach” and immediately begins a descent to the published altitude of the first segment of the instrument approach procedure (IAP). However, our pilot is quickly instructed by ATC to return to the assigned altitude and is informed of a possible pilot deviation.
There is a full explanation based on FARs in the article, too.
Peter wrote:
Is that after an IAF?
In this case yes. It also applies for published segment of a transition route or other published route for which a lower altitude is published on the chart.
Or would it include say a holding pattern which preceeds an IAF?
Crossing the IAF (holding fix) outbound you can descent during the entry once cleared to descend or cleared for the approach. The entry will keep you in the protected airspace of the hold.
When I trained for my first IR I was taught that on entering the MSA circle to call up and say “inside the 25 miles request descent”. There is no TAA at the time but when they were introduced I would still do the same. I would also request any staged descents within the MSA or TAA. In my head even if I was cleared for the procedure, that didn’t start until the IAF.
I have to admit that in more modern times I normally got a call from ATC with a " report ready for.descent" or “descend xxxxft” before I had to ask.
In US, being inside the MSA grants no permission to descend based solely on an approach clearance. With a TAA, if one is cleared for the approach prior to entering a TAA segment, as soon as one enters the TAA segment, they may descend to the TAA segment minimum without further instructions from ATC. If the approach clearance occurs when inside the TAA segment, descent to the charted TAA segment altitude may occur immediately unless ATC explicitly restricts descent. A simple clearance for the approach may not be issued if the aircraft is below a TAA segment altitude because the aircraft would have to climb to the minimum altitude. If the aircraft was inside the TAA, above the MVA, they may be cleared to an IAF as long as they are not cleared for the approach until on a segment they are at or above. So for example, assume a T style RNP approach with three IAF, RIGHT, LEFTT, and CENTR as part of a TAA. RIGHT and LEFTT are the base leg IAF entries and meet at CENTR (IAF/IF) which connects to the FAF. The TAA segment that includes the RIGHT IAF has a minimum charted altitude of 4000 feet, but the aircraft is in an area of the RIGHT segment where the MVA is 2000 feet and the charted minimum on the segment between RIGHT and CENTR is 3000 feet. A clearance similar to this would be acceptable, “Cleared direct RIGHT, maintain 3000 until RIGHT, cleared RNP Rwy 12 approach”. 2000 feet would work only if it was also the MVA for the route from RIGHT to CENTR and the minimum on the route from CENTR to the FAF was 2000, then the clearance could be “Cleared direct RIGHT, direct CENTR, Maintain 2000 until CENTR, cleared RNP Rwy 12 approach”.
OK so my conclusion to tell ATC my intentions (will level at 5000 overhead [waypoint]) seems to be quite appropriate. Because this is an implicit request for descent to level off at a certain altitude. ATC then can refuse this, but I’m not descending without negotiation.
Typical airline SOP is to be highly MSA vigilant. In the climb on the initial altimeter cross check, also registering MSA achieved. When descending, having briefed MSA, confirming a cleared altitude or FL is MSA safe. If on RV and being descended below MSA, with the situational awareness of the Minimum Vectoring Altitude chart, stating MSA Vectors, and if below MVA and visual to maintain own terrain clearance, then MSA Visual.
It is not untypical to be vectored on an ILS above platform altitude due to MVA limitations, and receive a ‘when established descend with the glide slope’ clearance. This is usually when vectored for a longer run in to the FAF. It doesn’t mean descend to the platform altitude when established on the localiser, a usual source of confusion, as this might compromise obstacle clearance.
In the same vein, a clearance for a procedural approach would be in the context, strictly, of descending when established on the procedure turn outbound.
Am somewhat allergic to accepting vectors on an RNP approach, mainly because having to maintain SA for potential intermediate step down limitations in the TAA. UK ATC seems to share this allergy and vectors are typically to one of the IAFs, at or above the MSA for the IAF, and then receiving the approach clearance, where you follow the procedure with the relevant crossing altitudes,
UdoR wrote:
OK so my conclusion to tell ATC my intentions
Universal way to go.
Always request what you need. If you don’t like what you get, negotiate. If in doubt, query. If still in doubt, query again. Keep decision making in the cockpit and stay safe.
Keep decision making in the cockpit
That is actually one of the most important things in flying.
It is easy to be afraid of ATC (most of us have been taught exactly that) and screw up.
