Altitude restriction apply on SID if cleared to altitude?

[P-air]

Not quite sure,

When cleared for a SID, and cleared to climb to an altitude, are you restricted to reach/maintain altitudes until passing certain points that have the altitude restrictions and continue to climb to the cleared altitude, or are you simply cleared to climb all the way to the cleared altitude unrestricted?

[212man]

You have to respect the step limits; you cannot just climb to the cleared altitude. The vertical perofile is just as important as the horizontal one, so missing out altitude restrictions is analagous to cutting off corners and missing waypoints.

[Semaphore Sam]

212 is correct; however, in my previous employment, the local ATC, if one was cleared, for example, to FL350, expected an 'unrestricted' climb to this altitude, contrary to proper practice. If ambiguity exists, one should ask if the climb to FL350 is "unrestricted"; ie, altitude restrictions up to the cleared altitude are rescinded for your climb. However, when my local ATC was thus queried, they expressed dumbfoundment, so ambiguity was not formally resolved. One makes a 'best choice'...and hopes for the best.

[gengis]

Here's another spanner in the works: you are cleared for an SID with published altitude restrictions, then at some point ATC clear you direct to a waypoint. In most places the alt restrictions at the intervening waypoints which are now bypassed would not apply. But in oz - specifically SYD - ATC still require you to comply with those restrictions as you pass abeam the original points in the SID. So if you have have Honeywell FMC, don't just line select to the top; select abeam points as well & check that the height constraints are still in. Be careful of the differences.

[IORRA]

Interesting point there re SIDs @ SYD there, gengis. I'm not sure I agree though. In most cases out of SYD, direct tracking following a SID is prefixed 'Cancel SID', which (as I understand it) cancels all SID-specific requirements and restrictions, including crossing heights and altitudes unless specifically mentioned by the controller. I can't find a ready reference for situations without the 'Cancel SID' instruction appended to direct tracking, but will scour the AIP tomorrow. In any case, will see if I can get a SYD controller to shed some light on it...

IORRA

[Icebreaker]

gengis,

it depends a bit of the wording in the re-clearance.
For example if you were instructed "CANCEL SID, RECLEARED DIRECT TO XYZ" then if ATC required constraints to remain, you would get something like "SID ALTITUDE REQUIREMENTS STILL APPLY" added on.

I would suggest to take notice of the exact wording given in the reclearance especially to get the "cancel SID" and of course ask for clarification if there is any doubt.

:ok:

[gengis]

Icebreaker,

"it depends a bit of the wording in the re-clearance.
For example if you were instructed "CANCEL SID, RECLEARED DIRECT TO XYZ" then if ATC required constraints to remain, you would get something like "SID ALTITUDE REQUIREMENTS STILL APPLY" added on."

Been some time now since i flew to SYD. That was with my previous company. But from my own recollection, "CANCEL SID, RELCLEARED DIRECT...." or "CLEARED DIRECT ...." was the usual terminology. Certainly don't recall anything specific like "SID ALTITUDE REQUIREMENTS STILL APPLY" being used, which would no doubt have cleared up any ambiguity before it becoming a problem. Though i am glad not to have had this specific problem myself with ATC in SYD, there were enough occurances of this nature, ie inadvertant altitude busts in SYD with my company for this reason, for ATC to actually write in to Flight Operations to highlight the point. Which was diseminated to line crew via crew circulars.


IORRA: I would really like to hear anything you can find on this from your buddies in SYD ATC. It'd sure clarify an important point.

[PPRuNe Radar]

In the UK and the USA, a new level clearance cancels all previous level restrictions unless the controller restates them as part of the new clearance.

[gengis]

Radar: that's what seemed to cause the confusion. I stand corrected about the SYD example - actually it was direct clearances given along a STAR, arriving from the west.

[Herc Jerk]

P-air

From what i've seen so far they'll normally step climb/decend you to alts on the SIDs STARs if they want you to meet them- BUT... not always.

The standard phrase that they'll understand is "confirm unrestricted climb/descent"

Hows your "say again" count going?;)

HJ

[P-air]

thanks for all the replies, definately seems to be different interpretations/practices depending on location of operation.

But yes, only way to clear it up is to "confirm unrestricted climb" ;)

though can be busy when recleared new sid, halfway through a procedure turn and yet to pop in the autopilot, :ugh:

HJ, nice to see your presence, "SA" count = ((1/2 number of transfers) + (2 x every hour airbourne)) / length of total time airbourne

so yup, getting better ;)

[IORRA]

Hi gengis

I've just spoken to an ATC mate from the SY TCU, and he confirmed that the phrase "Cancel SID, track direct..." implies that all restrictions noted on the SID plate, including SID-specific altitudes and speed restrictions, are waived (obviously N/A to generic restrictions such as 250 blw 10,000ft without further instruction).

Interestingly (and I didnt realise it), it also cancels the generic altitude vs. SY DME restrictions that appear on some plates for departures via ENTRA (etc), unless the controller specifically appends 'Special Requirement still applies' to the 'Cancel SID' instruction.

Hope this helps!

IORRA

[212man]

Pprune Radar,
just to confirm what you mean, and that I haven't misunderstood the rules, could clarify the following examples, please?

An aircraft wishes to depart on XYZ SID to join an airway with a flight planned level of FL200. The SID has two step altitudes of not above 2500 ft at A and not above 5000 ft at B with a final exit point of FL110 at C.

In the first instance the clearance is XYZ SID to join the airway at FL140, with a level change requst en-route. My understanding is that you would comply with the two altitude restrictions. Correct?

If, during the climb in the SID the controller recleared the aircraft to FL200 (as planned) are you saying that you could now ignore the two altitude restrictions (or, more likely the second one as you'd probably have passed the first)?

Sorry I haven't refered to a specific example, that might have been easier.

Cheers

[despegue]

In my humble opinion:
when with your ATC clearance you get another altitude/FL than the one mentioned on the SID, this means that the alt. restrictions below your cleared alt/FL. have been cancelled except for minimum alt. at certain points and climb gradients .

Any ATC clearance overrides your little papers before your noses.

Check your doc. 8168 and 4444 please.

[deadhead]

despegue is correct, and for further reference your AIP should be able to help. Of course, notwithstanding possible frequency congestion, there isn't anything wrong with getting a clarification, as someone has already suggested.

SIDs are a procedural method of separation, of course; they come into their own should the departing aircraft fail to come up on the correct frequency after take-off, for whatever reason (RCF, finger trouble, etc). Any published hold-downs are usually for the purpose of providing vertical separation, most usually against arrivals, which will be held higher; it stands to reason then, that if there is no conflict, ATC may clear you to a higher altitude (but in rare cases the restriction may be to avoid restricted airspace, eg military transit lanes like at Tel Aviv, and in these cases ATC should only clear you higher by re-introducing the hold-down in a discrete and specific re-clearance - otherwise they should WAIT until you have passed the hold-down point).

However, they may still want you to track the SID in an azimuth sense, hence in this case the SID is not cancelled. This is likely whenever there is a conflict in an azimuth sense, naturally - and is most applied if there is departing traffic of differing speed ahead or behind you. Chances are, their SIDs were or will be cancelled entirely.

You can look at it another way; you won't be cleared to an altitude if someone is in your way, published "not above" altitudes or no, errors notwithstanding. Of course, you could get a step climb that replaces what is published if the new clearance can expedite your departure. That's the theory, anyway!

Of course, climb requirements for terrain clearance purposes must not be set aside at any time whilst climbing a SID - that is, climb gradients and "not below" altitudes must always be complied with.

It would be helpful if the docs quoted above were easy to read, or the national AIP were better written, or if ATC, for the sake of a couple of extra words said: "Track via the SID, climb unrestricted to FLXXX" where the meaning of this phrase is clearly stated in AIP etc as meaning that any climb restrictions (hold downs) are lifted etc...

[bookworm]

Check your doc. 8168 and 4444 please.

These are large documents that cover many issues in very different levels of detail. If you're going to cite documents, please give a reference to the words that support your assertions (which I don't disagree with).