Cleared for approach prior to the IAF - when can you descend ?

['I' in the sky]

Situation:

Aircraft has previously been cleared to a VOR at 5000', The VOR is the IAF for an approach where the outbound leg of the racetrack is a minimum altitude of 2600'. About 7 miles from the VOR, approach clearance is given.

When I learned in the US the FAR's were quite specific that in this situation you maintain your last assigned altitude until the IAF and then you can descend in accordance with the approach procedure and your clearance.

Where I'm flying now (Spain) it seems that eveybody is quite happy that once the approach clearance is received you can descend straight away to 2600' as long as that's not below MSA for the sector from which you're approaching the beacon. Is this in fact the correct thing to do ?

Can anybody point me to a reference to this in the AIP, PANS-OPS or something else official. I can't find one. I can find plenty of people who think they can reason why it should be OK to do this but not actually provide a reference.

Thanks in advance.

[tori chelli]

Can't provide a reference I'm afraid. However, logically, if you're "cleared VOR/beacon approach..." then you should be able to descend to 2600' in the holding area which should be terrain-safe. Personally I control & teach that you instruct descent to 2600' and [I]then[I]clear either for the approach, or "descend with the procedure". That way there's no ambiguity...& ambiguity is what gets people into trouble!:D
Tori

[Pierre Argh]

ahh.. another grey area. IMHO if the procedure specifies a minimum holding level at the IAF then a pilot cleared for the procedure should not descend until they have departed the IAF outbound on the procedure (although I can see the safety arguements expressed in other posts re: terrain clearance, it is not what I would expect and have planned for. I have seen a couple of pilots do just that though, and fortunately it didn't cause a problem (just bewilderment) at the time.

I watch this one with interest...

[Scott Voigt]

The reason that we do it that way in the US is because there was confusion many, many years ago by some flight crews, and one B727 flight crew were arguing about it just prior to hitting the hill near Dulles... It's why now we all say Maintain XXX till XXXXX cleared XXXX approach. It is also why the ATPAC (Air Traffic Procedures Advisory Committee) came into being, because one airline figured out this was being done and told their crews about it, but it wasn't getting to other airlines.

regards

Scott

[Legs11]

I've always been taught not to clear an aircraft for a procedural approach unless the a/c can descend to the initial approach level stated on the plates. If cleared for the approach, there is nothing to stop you carrying out the approach.

[Tiberius]

Using the example provided, wouldn't the phrase "descend to 2600,cleared VOR approach' remove any confusion?

[Pierre Argh]

How about the procedure at XXXX where the minimum level at the IAF level is MFL. In the incidences I have seen of "early descent" traffic, that has still to reach the IAF but has been cleared for the procedure, has descended to the Intermediate altitude... i.e. crossed the IAF at a lower level than the minimum (but still above Safety Altitude)?

[SixDelta]

To throw my two pence in...

If cleared for a VOR approach with a descent to 2600' on the outbound, i would hold my cleared level until "beacon outbound" at which point i'd commence the descent regardless of what my VNAV wanted to do.

On another similar point. If flying level in the hold (eg 3000'), cleared for the approach which includes an outbound descent to a platform altitude (eg 1900') for the inbound turn do ATC expect you to commence descent immediately on leaving the beacon "outbound" or will they accept you descending when the VNAV commands for its continuous 3 degree descent path.

In our a/c the kit will maintain the holding altitude until it's in a position to fly a constant descent including a descending inbound turn to intercept the glideslope (from below, just) if you let it.

['I' in the sky]

Thanks for the replies so far.

So question to the contollers. Would it be fair to say that an approach clearance will not be given until all potential traffic conflicts between the cleared aircraft and the IAF have been resolved ? It seems we are all happy to ass-u-me this to be the case but the we all know what....

Legs 11, I appreciate what you are saying but the approach starts at the IAF so the question really was, can you descend to the intitial minimum approach altitude prior to the IAF because even though cleared fo the approach, you are not yet in the approach procedure ?

Tiberius, yes it would, which is what tori chelli says he does however they rarely if ever do that here. Only when you request clarification do they usually reply by confirming your approach clearance and then qualifying it with "descend at pilots discretion" and as Mike Jenvey has experienced, usually in a tone that suggests you have asked a stupid question !

Scott, yes but, even if you didn't say "maintain xxxx until xxxxx, cleared xxx approach", the FARs say you have to anyway - no debate.

[Pierre Argh]

can you descend to the intitial minimum approach altitude prior to the IAF... Depends what you mean by "Initial Minimum Approach Altitude". The Initial Approach Segment commences at the IAF and ends at the IF, before that, IMHO, you should be flying at the Sector Safe Altitude. Descent below that level before passing the IAF may not provide terrain clearance (hope this isn't another case of Intl Variance?)

Regarding other traffic... for our "on airfield" NDB the IAF/hold is, naturally, in the overhead. If I clear traffic to the IAF and out on the procedure I think I'm entitled to expect the pilot not to fly below the minimum holding level until beacon outbound?

Am I wrong?