RNAV or ILS DXB
 

Arriving at DXB yesterday was a little frustrationg.

Each controller gave us a different expected approach, alternating between ils or rnav for 12L.

Finally (when at 4500') cleared for an intercept for ils 12l my colleague pointed out that we had previously been told to expect the rnav. So the controller changed his mind and said " cleared for the rnav 12L, descend to 2000'".

Are controllers aware that this clearance kind of defeats the point of rnav and makes the workload unnecessarily higher for us. If we're cleared for the approach why give us a descent limit?

What we want is to be cleared to fly the approach as early as possible, perhaps only accepting small speed corrections limitations.

There was no-one close in front of us but departures seemed busy.

Hi
Not sure why you had confusion on RNAV or Loc/dme? We norm offer the RNAV them Loc/dme if people cannot accept RNAV. As for the decent to 2000ft this is the start level for the procedure and ALL of the local operators ask for decent to 2A for the procedure! Plus the controller may have needed the vertical separation again preceding or other traffic in TMA.

At present ILS approaches are not available to Rwy12L at DXB due to GP interference caused by WIP at the west end of November twy. RNV is also the preferred approach to Rwy30R as an ILS approach restricts some of the holding points we use on the north side and also the usage of the R/R1 twys in the undershoot. It's probably notamned.

I don't fly often to DXB, and would like to clarify what ATC expects in this case:

I was told to descent to 3000', at 3000' I was cleared for the RNAV 12L approach. The procedure starts at 2000', can I stay at 3000' waiting for the vertical path, or should I descent to 2000'? Sure, for me, is best to stay at 3000' and wait, but what ATC expects?

Descending to 2000 feet before being cleared to descend even though you have been cleared for the RNAV approach can be dangerous. ATC expects you to descend at the correct vertical path. If in doubt when operating during busy hours please ASK. Assume nothing; we are after your safety and if ATC has made a possible mistake do not compound the situation by making another one yourselves. Cheers:ok:

approach clearance
 

ricfly744

pretty much the world over (I wont say definitively) when ATC clears an aircraft for an approach, as well as clearing the aircraft to fly that approach it also effectively clears the aircraft to the ground and also for the missed approach (if this is required from the MAP).
Falcon is correct in that ATC would expect the aircraft to fly the appropriate vertical profile/path, however, the controller should protect that airspace underneath your aircraft track in the possible event the pilot decided to descend to the minimum altitude (ie the controller SHOULD NOT slide another plane underneath you expecting you to wait at a higher level until you intercept the vertical descent profile for that approach...that's not positive control that would be shear idiocy.

I didn't say "confusion", I said "frustration".
Nor did I mention Loc/Dme. The ILS was notammed as u/s but we were offered it ,and cleared for it too.

2000' is NOT the "start level" - there is no such thing.

I cannot explain why "ALL" the local operators would ask for descent to 2000' as this makes flying a continuous descent more tricky. Maybe they are choosing to fly level at 2000' and intercepting the 3deg approach path.

We prefer to stay at 3deg descent all the way as it's more fuel and noise friendly.

Your last comment is a little worrying. If we are cleared for the RNAV then - by definition - we are cleared all the way to the MDA. So to the include a descent limit point makes the clearance invalid. If you want to have the possibility of clearing other a/c below the RNAV then all you need to do is include minimum heights on the procedure.
But (if you understood the principal of RNAVs) a/c will be on the 3deg approach path after the FAF!

Well all of the GNSS approach plates tell you to maintain a procedure height of 2000ft until a decent start point eg on 12L 2A until DB601 then descend on a 2.8deg approach path??

Blu,

I could easily understand start level to be platform altitude?? Why shout??

Having checked charts, the platform altitudes for all RNAV approaches into Dubai are 2000'. If he doesn't clear you to that altitude, how could you start the approach? Even Heathrow does it that way! CDA's are preferable we all agree on that... But I imagine if you ask nicely to start the procedure from so many thousand feet there would be little resistance...

Being initially cleared to 2000ft on a RNAV approach doesn't mean you have to fly a level segment at 2000ft. Just like with being vectored for an ILS approach. If you wish to fly a CDA then there is nothing stopping you in doing so.

I'm based in DXB and for the fleet I am on at least, there is no procedures that prevent us from flying a CDA on an RNAV approach. It's how most guys will fly it anyway as it makes life easier.

I agree that platform height is 2000'.
The implication seemed to be that "ALL" local operators "start" level at that height.
Cough's comments appear to support that, whereas I agree with Emma.

Wasn't shouting - where did you get that idea?

I still believe that at - say - 4-5000' if you are cleared for the approach then that should be the clearance to MDA - without an intermediate descent restriction.

Riband, I certainly didn't read the OPs post as an implication the locals start level at 2000ft. He simply said they ask for descent to 2000ft. You imply you were under radar vectors therefore I'd always ask for descent to an appropriate level for the approach we're shooting for.

In my experience, controllers, if vectoring me, may say 'Descend altitude 3500ft, Turn left leading 040, Cleared ILS approach RWY 01', and then after a few minutes 'Descend altitude 2000ft'. I would never consider descending below the initial restriction of 3500ft without further clearance unless I established on the localiser. Nobody I know in my company would take a 'Cleared Approach' clearance as a 'descend on discretion' while in 'No mans land' on radar vectors before they establish on part of the published approach profile - localiser, inbound course, etc.

Got the shout from your caps...

CDA into LHR - Cleared 3000', aren't we always on the glide well before that?

CDA into DXB - Any different? But procedurally what did the ATCO do wrong apart from the clearance being a little reversed? If they had said 'Descend to 2000', cleared RNAV...' I would interpret that to be descend to the platform and complete an RNAV approach and if you choose to turn it to a CDA, that would be within the clearance as issued.

I totally agree if I 'clear you' for an approach from what ever level I give you, norm no higher than 3A (old ILS protection requirement!!) then I expect you to descend with nominal glide path. However I would say 80% of people ask to go to 2A to start GNSS?

AFAIK there is no mandatory @2000ft at the IAF. There is however a minimum safe altitude published for the initial segment.
Some STARs where I work have minimum safe altitudes of e.g. 5000 ft on two consecutive segment split by a waypoint with a hard constraint of @FL90.
The minimum altitudes are just to show at what altitude the procedure is protected in relation to terrain, and in some cases airspace.

Yep. One's an ILS. And you're not cleared for the approach yet.

We're talking about RNAV which is an autonomous VNAV approach.

Please go back to my original post. I said that the controller in DXB told me I was cleared for the RNAV but only to 2000'. Why?

Just guessing here but I think it was simply done in the wrong order.

The controller made a mistake, corrected themselves by clearing you for the RNAV and and while doing that realised you were only cleared to 3000. They then probably figured your next call would be to ask if you could continue to 2000 (which we get more often than not if we clear someone for the RNAV from above that), so added on the clearance to 2000.

Yes, that then made it confusing and I would understand someone wanting to reconfirm if they were still cleared for the approach but not everyone round here would.

Not the ideal thing to happen but with us doing so many different airports, where approach types are changing all the time, I'm afraid we are only human.