Cleared Flight Level ?

[jackieofalltrades]

I agree with what sellect says.

If I wanted you to remain at FL 150 until waypoint XXXXX I would instruct "At XXXXX descend FL 130." If I had cleared you to FL 130 before you had reached XXXXX I would expect you to commence your descent upon readback of my instruction.

My response was posted at 17.26 UTC, but due to the time stamp fairy it is showing up as first on the thread.

[wanchman]

Hi all, can anyone shed any light on the the following question?

The scenario is as follows : on a STAR under radar control and ATC clears you to descend to a flight level using the following EXACT phraseology-'descend FL150, reach by XXXXX'(waypoint). On your Jepp plate it has the waypoint XXXXX in a box stating 'At FL150'. If ATC then clear you to a lower flight level, eg FL130, before reaching waypoint XXXXX stating ONLY 'descend FL130' , are you cleared to continue descent to FL130 only after crossing waypoint XXXXX at FL150 or can you continue your descent to FL130 before reaching waypoint XXXXX.

I know the easiest thing to do is ask ATC if there is any doubt but sometimes this is not always possible.

cheers,

wanchman.

[sellect]

I would say if atc says descend FL130, then you are cleared to disregard the level restriction, unless they say after XXXXX descend to FL 130.

[Neptune262]

Please see this thread below:

ATC assign descent below altitude constraint while on a RNAV STAR

and also the following doc:

http://www.caa.co.uk/docs/33/FOD201009.pdf

Cheers

[055166k]

wanchman

In the UK any new instruction cancels the previous instruction. If the controller intends the original restriction to remain he/she should include the restriction in the new instruction. In your example "Descend FL130" means descend FL130 [now]. If the restriction still applies the controller could say for example.."Descend FL130 cross XXXX FL150" or "...after passing XXXXdescend FL130". Several different ways of saying it. In the UK most STAR charts specify that Actual descent clearance will be given by ATC......meaning that the STAR chart is a descent planning guide. The STAR chart gains more relevance in the R/T failure situation.......depending on what clearance you had actually been given prior to loss of communication. This is my opinion.....others may wish to contribute.....particularly if other States have different procedures.

[wanchman]

good gen, many thanks for the replies!

[Not Long Now]

Slightly off track (or more precisely, off level?), discussed yesterday with a fellow controller who is also a professional pilot, RNAV approach procedures should not be offered if temperature is below -10C as vertical component of tracking may be subject to considerable error (150ft?). So, if it's quite, but not extremely cold, the ground may be closer than you think, or indeed further away. Now is this RNAV error the same when at cruising altitude, where I'm guessing it's considerably colder? And if so, is it a consistent error so the guy supposed to be 1000ft above you is also on same error and you are indeed 1000ft apart, a random error, so you could be too close or over separated, and if the other guy is not RNAV will he be at exactly the right level and so too close or further away than required?
Answers on a postcard please.

[blissbak]

There is no correlation between RNAV and vertical separation of A/Cs, isn't it?

[Dallila]

Hi there!I work as an ATCO and I know that according to what is written in the procedures,the pilot should comply the last thing the controller is saying-so,if he cleared you first at FL150 as to be leveled by point XXX,and after you are cleared at FL130,you should continue descend,even if you are 15 or 20 NM inbound pointXXX.