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Altitude restrictions

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Old 30th Aug 2000, 15:46
  #1 (permalink)  
Sink Rate
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Unhappy Altitude restrictions

May I pose a question to you all as to altitude restrictions on SIDS and STARS?
If say you are flying flying a STAR and the controller clears you down to, say FL180, level by ABCDE.

You look at the plate and it says "thou shalt be at ABCDE AT FL180". Easy so far.

If then ATC clear you down to FL140, before you have reached ABCDE, are you still then expected to meet with the AT FL180 AT ABCDE restriction and then continue descent to FL140?

I think not, but some of the guys I fly with seem to think so, others aren't sure. Also vice versa with a SID and climb clearances.

What are your opinions of this. I am especially interested to know what our TC controllers think/know!?

Thanks in advance.
SR

 
Old 30th Aug 2000, 23:28
  #2 (permalink)  
Buffy Summers
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Unhappy

I believe its the same whether SIDs or STARs - you should ask if "unrestricted" climb or descent. ie. climbing on SID, have to cross point A at 3000 feet, ATC clear you to FL160 (unlikely, I know), your reply should be "confirm climb UNRESTRICTED FL160?". However, I also think that ATC is meant to say "climb/ descend "unrestricted" XXX".
Perhaps a controller can confirm?
 
Old 1st Sep 2000, 06:05
  #3 (permalink)  
TinPusher
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Unless the restriction is cancelled formally I would expect you to still comply with the Fl180. The only time I would expect you not to meet the restriction would be if you were stopped off at Fl190 or above.
 
Old 1st Sep 2000, 14:17
  #4 (permalink)  
Sink Rate
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Is there anything formally written down regarding this matter. It seems that so far it is personal opinion as to what restrictions apply.

Any other controllers care to comment? (Perhaps someone from CATC?)
 
Old 2nd Sep 2000, 19:13
  #5 (permalink)  
PPRuNe Radar
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Sink Rate,

In the UK, level restrictions on STARs are placed there for flight planning purposes so that crews may plan their descent profiles and fuel loads. They are not cleared levels and there is a plain language message on the STAR charts which states that actual levels will be assigned by ATC.

Now if ATC have cleared you down to FL180 level by ABCDE (which matches the published profile on the STAR) and then subsequently reclear you to FL140 by VWXYZ but do not mention the original restriction, then that original restriction is automatically cancelled.

SIDs are subtley different in that the restrictions published in them are actually part of the ATC clearance (a SID is in fact just an ATC clearance which is charted to cut down on RT). These restrictions are placed there to ensure terrain clearance, noise preferential routeings, and ATC procedures are all complied with.

Strictly speaking, ATC clearing you above the SID final altitude would by default cancel all other restrictions in the SID, however as the pilot you are still responsible for ensuring that you follow the noise preferential route (and altitude elements) plus maintain terrain clearance. As most pilots are busy after departure I would imagine they would just continue with the SID restrictions rather than work out for themselves the levels they need to be at to ensure compliance.

Examples of SID & STAR charts from the AIP can be found here. Just pick the airfield you want. The references to levels, NPRs, and climb gradients for terrain purposes are contained within the notes of each chart.


http://www.ais.org.uk/uk_aip/pdf/ad/aipad2.pdf

'Unrestricted climb/descent' is not in UK pharaseology.

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Old 2nd Sep 2000, 19:41
  #6 (permalink)  
gaga1976
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On STAR, if after "...descent FL180 by ABC" we get "...descent FL150 by XYZ" it is clear to disregard first restriction. What happpens when second clearance is just "...descent FL150"?
If after "...descent FL180 by ABC" we get radar vector (from "present hdg to left/rigt 90*) are we to be given level abeam given point (hard if hdg change is big)?
For SID: In UK we have altitude restrictions on chart and initial level is not given in Clearance-pre-taxi (you take it from chart). In other places like Madrid, Rome... there are max altitudes on chart (at or bellow), and clearance altitude is higher. You can climb clearance level only passing these points. Does the departure ATC clearance above these altitudes before these points cancels SID restictions?
 
Old 2nd Sep 2000, 22:22
  #7 (permalink)  
Grandad Flyer
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PPrune Radar, I love this forum, I learn so much!
Anyway, here is a question about SIDs. Lets take the STN CPT 3R as an example. There are two stop heights, both 3000 feet (for historical reasons I suspect), one before BKY and one after BKY. We almost always get cleared to FL70 prior to these points, then generally we will get radar vectors at some point further on, but we always go for an "open Climb" which means we don't stop at the stop heights. We do usually say "climb unrestricted" but now you have posted your reply above, I think we are doing this wrong and should maintain the 3000 feet limit until we're past the second (post BKY) stop height and then climb to FL70. We always follow the SID laterally.
It has never been queried by ATC.
Its not a problem either way for us to do in the aircraft.


 
Old 3rd Sep 2000, 01:36
  #8 (permalink)  
identnospeed
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G'dad Flyer,

Clearance to FL70 is unrestricted in the case you mention. If a controller wanted you to comply with the the SID altitudes as per the plate, then he/she would not clear you to FL70 in the first place.

We get a lot of US pilots asking the same type of question. This is due, I believe (?), to the nature of American SIDs where a clearance on a particular SID requires the a/c to follow the particular profile stated and aircraft are not generally authorised by ATC to deviate from that profile.

Sink Rate,

With regard to STARs : you may be istructed to be FL200 level 20nm before ABCDE and later told to be FL150 level ABCDE. The book says that the ATCO must restate the previous restriction if he/she wants you to still comply with it.

In practice this is never done.

Due to the requirement to fly standard speeds unless otherwise instructed, which involves a speed of 250kts at, say, ABCDE; most a/c need to be at FL200 level 20nm before ABCDE in order to make the 150 level by ABCDE AND reduce to 250 kts by that point.

Almost all the STARs into the LTMA are constructed in this way. And if you ended up being 200 level 17 miles before ABCDE (ie. 3 miles late) I don't think any radar controller would notice.

These STAR restrictions are usually designed to avoid you entering the airspace of a controller who has no information on your flight. However, they are generally not so tight as to be dangerous if missed by a mile or two.

INS
 
Old 3rd Sep 2000, 02:09
  #9 (permalink)  
PPRuNe Radar
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Grandad Flyer,

Sorry, I was not as precise as I should have been. When I was talking about pilots still complying with SID restrictions even when cleared above the final SID altitude I was thinking more about the cross at or above levels rather than the stepped climb ones.

For the stepped climb ones, identnospeed has hit the nail on the head, the restriction has been removed and therefore you may climb on the vertical profile as you see fit, subject noise and terrain constraints.

That should be all the angles covered now

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Old 3rd Sep 2000, 03:27
  #10 (permalink)  
TinPusher
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It never ceases to amaze me that when most of the worlds procedures are based on the same ICAO recommendations there is still so much conflict of opinion on matters that are really very important.

In Sink Rates original scenario a published (standard) restriction is reiterated by ATC ie Be level FL180 by ABCDE.ie He/she wants you to comply. Subsequent descent to FL140 is NOT a restriction, it is issued to prevent the acft leveling at FL180 when there is no need to do so. In my opinion the original restriction still applies!

Where the 'Be level FL180' is followed by a further restriction, as in gaga1976's scenario, where a further restriction is added then the original restriction is cancelled unless ATC reiterate.

Pprune radar, I agree that level restrictions on STARS are not cleared levels, however if cleared levels are issued that will enable the flight to comply with the STAR profiles (as they should 90% of the time or there is little point in having STARS) then it should be a valid expectation that the flight will comply unless they are specifically cancelled, in the same way that speed restrictions and max entry levels to holding patterns should be complied with unless ATC has issued a specific clearance to disregard what are standard procedures.



[This message has been edited by TinPusher (edited 03 September 2000).]
 
Old 4th Sep 2000, 23:03
  #11 (permalink)  
PPRuNe Radar
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TinPusher,

Part of the problem is that ICAO procedures are very generic and never go into the level of detail which States tend to publish for their specific operation. Their advice on reclearances tends to cover changes to flight plans, destinations, etc. There is nothing I can find on the scenario we are discussing. Also looking in the ICAO documents for phraseology terms, there is no ICAO phrase such as that suggested by Buffy, the only vertical reclearance phrases are 'Stop climb/descent' or 'Recleared'.

Both the UK and US procedures are quite specific however, and that is that all restrictions for a particular element (level, speed, time or route) are cancelled in a reclearance of the same element.

In Sink Rates example the descent clearance to FL140 is a reclearance, replacing the original clearance which was FL180 level by ABCDE. The fact the original FL180 was given as a restriction doesn't change the fact it is a clearance whether stated explicitly by ATC or as part of a published SID/STAR on which the aircraft has been cleared (these types of routes are just documented ATC clearances after all).

Unfortunately I don't follow your logic on restrictions I'm afraid. I apologise if I've misunderstood. What you seem to say is that if the aircraft has a restriction A (lets call it FL180 by ABCDE) and is then given a reclearance to FL140 with no restriction stated, then you still expect the pilot to comply with restriction A. Yet if he is given restriction A, but instead of a free descent is given a descent to FL140 level by VWXYZ (i.e. restriction B), you would only expect restriction B to be complied with. What's the difference such that restriction A is assumed to be cancelled in one case but not the other ?

In the UK and the USA, there should be no doubt. The controller is required to reiterate the restriction if they want it to apply. Now, what many people do in my experience is to monitor the profile being followed and issue the reclearance when it is obvious that the aircraft is going to make the restriction anyway. So we do not physically reiterate the restriction, but manage the traffic profile so that it complies anyway. This echoes what identnospeed says.

I think your last point will very much depend on what the STAR chart says. For the UK, the published levels are for guidance. If the controller wants the pilot to comply with them then they have to pass that as part of the clearance. It would not be good enough for us to simply clear the pilot to FL180 and then expect them to cross ABCDE at that level as per the chart, because that is not what we have cleared the pilot to do. Other countries may have different procedures and have 'hard' altitudes on the chart. In those cases what I have heard is the pilot being cleared to follow the STAR 'with the profile'. No descent clearance is passed and the pilot is expected to follow the route both laterally and vertically.

As to why have STARs ?, again from a UK viewpoint, the prime purpose is so we know where the aircraft are going to fly laterally. The vertical elements are enshrined in ATC procedures such as Standing Agreements between sectors or airfields so when it's busy the profile will be followed by the clearances issued, rather than the pilot being cleared to follow the profile on their own. However these vertical profiles, which are often not ideal in economy terms, are relaxed when traffic permits. In fact sometimes in the quieter periods the controller will be working both the sectors for which the profile has been designed (for ATC co-ordination purposes). So unless they have a split personality (mmmmm, in ATC that is quite possible !!), the restriction can be lifted and usually is, saving the crews a couple of Kg of fuel.

I agree with you that speed restrictions should be adhered to, but that is because the controller has generally not varied or lifted them. In the examples we are talking about the levels have been varied by ATC, thus overriding any restrictions.

Now we've got Grandad Flyers attention, I hope this lot doesn't scramble their brain too much

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Old 5th Sep 2000, 00:21
  #12 (permalink)  
Grandad Flyer
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You guys and girls in ATC always have my full attention
Basically you have just confirmed what I always thought was the case, and cleared up my error on "unrestricted" climbs.
Now, lets throw one more spanner in the works.
Why IS it that some pilots insist on saying "Charlie Charlie" instead of "affirm". I looked in my reggie spotters radio telephony manual and couldn't find it in there.
I think it might be an ex-RAF pilots thing.
I hear it ALOT on the Casablanca sector.
Please can someone confirm that this is non standard - we are always being lectured to about non-standard RT in our company and I would like this to be sorted.
Thanks!
 
Old 5th Sep 2000, 03:15
  #13 (permalink)  
PPRuNe Radar
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Grandad Flier

'Charlie' is definitely non standard, as is 'squawk coming down', 'out of 2 point 3 for 6', etc, etc.

Whilst these sorts of phrases may have their origins in days of old, the old tricks are passed on to the young ones coming through the system and so live on well past their sell-by date



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Old 5th Sep 2000, 20:38
  #14 (permalink)  
Sink Rate
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Wink

Thanks PPRruNe Radar et al.
That has just about cleared up my question (even if it did take me a bit of time to work through it!).

As soon as my head stops spinning I shall go to work and put in into practice!

Cheers!



[This message has been edited by Sink Rate (edited 05 September 2000).]
 
Old 7th Sep 2000, 13:52
  #15 (permalink)  
TinPusher
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Unhappy

I've been prompted to a little research and found that in NZ there is nothing published concerning this scenario, apart from a few phraseologies that apply to reclearances.

PPrune radar, I dont follow my logic either although I am sure I had a point...perhaps it was my other personality.

Whilst our manuals may be lacking, an informal survey amongst my collegues resulted in a 60/40 split on opinion, with the majority expecting the aircraft to be somewhere close to the published level anyway. Assuming the restriction is necessary it will be for a reason (read traffic) and where there is potential for doubt, good operating practice would dictate a confirmation or reiteration.
There are new FMS STARS soon to be published for Auckland that will have 'hard' altitudes published but they are all not belows for noise abatement and there is a comment stating that they are mandatory.

Here's another scenario:
SID has maintain 3000 to 10DME, the route clearance has cross 35DME 11000 or above. Aircraft calls airborne climbing 3000, is identified and given climb to cruise level (FL330). Does the 11000 by 35DME still stand??? I think it does given that the SID finishes at 10DME but there are some who disagree ie, give climb and you cancel previous instructions, including the 11000 by 35 (The SID and route clearance are published as Standard Route Clearances eg CHAA3)
This sort of stuff gives me a head ache


[This message has been edited by TinPusher (edited 07 September 2000).]
 
Old 7th Sep 2000, 15:05
  #16 (permalink)  
karrank
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Red face

The variety of views here is quite frightening! My experience in OZ on flight-deck famil at least encourages me that a cross section of OZ pilots understand the procedures.

Consider a STAR (which is also an ATC clearance which is charted to cut down on RT) with "reach FL180 by PRANG". For a start I would not re-state the requirement with a level assignment, the pilot has it already.

Even without a STAR I am most unlikely to assign "descend to FL180 reach FL180 by PRANG" unless I want the aircraft to maintain, or there is something else in the way. If I then assign FL140 (without a requirement) the previous requirement STANDS.
If I want to impose an additional requirement I must prefix it "additional requirement" or 180xPRANG is cancelled. So, with the above STAR:

"Descend to FL180," means "descend to FL180, reach FL180 by PRANG."

"Descend to FL140," means "descend to FL140, reach FL180 by PRANG."

"Descend to FL140, reach FL140 by AUGER," means "descend to FL140, cancel PRANG requirement, reach FL140 by AUGER."

"Descend to FL140, additional requirement, reach FL140 by AUGER," means "descend to FL140, reach FL180 by PRANG, and reach FL140 by AUGER."

Finally, (if anybody is still reading) I understand CC is an old morse thing, certainly beloved of Asian Aeradio operators.



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Old 8th Sep 2000, 14:56
  #17 (permalink)  
gaga1976
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Question

I still do not know if I agree with the way Karrank sees things about STAR restrictions but I LOVE the way he had put it. It's clear and concise.

"Descend to FL180," means "descend to FL180, reach FL180 by PRANG."
-All clear

"Descend to FL140," means "descend to FL140, reach FL180 by PRANG."
-This is the way 90% of people would do. Even if not correct, it's on a "safe" side and ATC won't bug you about it (you only burn few more kilos of fuel). I see CaptPPRuNe doesn't agree on this one

"Descend to FL140, reach FL140 by AUGER," means "descend to FL140, cancel PRANG requirement, reach FL140 by AUGER."
-Agree

"Descend to FL140, additional requirement, reach FL140 by AUGER," means "descend to FL140, reach FL180 by PRANG, and reach FL140 by AUGER."
-Never heard that one. It would be to much from ATC to expect we want to deal two restriction at the same time. There are other things to think during descent (weather, terrain, cabin rate...)

Q to you Karrank:
"Descend to FL180 by PRANG"
"Direct AUGER, descent FL140"
Does that means?
"Direct AUGER, descent FL140, be FL180 abeam PRANG" or
"Direct AUGER, descent FL140, cancel FL180 restriction by PRANG"

 
Old 8th Sep 2000, 17:33
  #18 (permalink)  
Sink Rate
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It's a minefield again! I'm not sure what I believe anymore!
 
Old 8th Sep 2000, 18:55
  #19 (permalink)  
LoLevel
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Star Requirement to Cross GUDIT not above 10000FT.

ABC when ready descend 8000, QNH blah blah.
Rog..
ABC descend 6000.

I am expecting you to still cross GUDIT BLW 10000, cos there is a good chance that level dovetails with a SID cross of FL120 or something similar. Even though on Radar it will be monitored I would still be expecting the ACFT to toot if he/she ain't gonna do it.



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Old 9th Sep 2000, 05:28
  #20 (permalink)  
PPRuNe Radar
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Sink Rate,

In the UK (and the US, which is unlikely in your fleet !!), it is perfectly clear. Restrictions are cancelled with any subsequent clearance UNLESS they are restated.

gaga1976

I have no problem with people complying with restrictions in charts even when they have been cancelled......the only pain is on the airlines fuel bill, possibly.

karrank

Oz seems totally different, including the phraseology....but then they also have TAATS !! Fortunately ASA have been ruled out of the bidding to buy the UK ATC system so this old dog will not have to learn new tricks


I vote the two busiest air traffic nations in the world get ICAO to adopt their standards, all in favour say aye !!



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