Level Restrictions

[barrelroll4separation]

Inbound AVANT for a Lorel 3C in STN this afternoon and issued the usual descent clearance to be level at FL190 by Avant. Approaching Avant we were given direct VATON. I would say we were passing FL220 at this point with around 10nm to run to AVANT. The FL190 abeam AVANT was not reiterated as part of the direct VATON clearance.

Could someone please point me in the direction of some official wording that would clarify the result expected by the controller. I know there have been previous debates pertaining to speeds and SIDs etc but I have not seen this be resolved by the CAA or NATS.

Thanks in advance....

[The Fat Controller]

I am afraid this has been done to death before.

ANY new clearance cancels the previous clearance.

If the controller wanted you to pass abeam AVANT at or below FL190 he would have to include this restriction in the new clearance.

Thread closed ?

Maybe, haha !

[windneckin]

Yes, the book says that a new clearance cancels any previous clearance but I think the book is referring to new clearances in the same "dimension" as the previous one... for example vertically. If you were told "descend FL190 level AVANT" and then told "descend FL150", that would cancel the AVANT restriction unless reiterated.

However, in your case, I think the controller would expect you to comply with the level restriction abeam AVANT.

I cannot see how a direct routing can cancel the level restriction on the descent... by that reasoning... any new clearance would cancel all the previous clearances if not reiterated. Imagine that you were told "turn right 5 degrees" and then "resume own navigation AVANT" ... surely the "turn right" would not cancel the level restriction.

[ZOOKER]

As always, if in doubt, ask. NATS is 'tuned in to its customers' these days, so if in doubt, (it's like buying insurance), just ask the Salesman, ATCO, or Customer Service Representitive.*

*delete as applicable. :E.

Wasn't meant to be facetious, just a bit of fun, but please, if unsure, do check.
Safe fiying!

[5milesbaby]

windneckin - wrong unfortunately. By giving the direct to VATON, the AVANT restriction is cancelled unless reiterated. You cannot expect a pilot to be level at a point they are no longer routing through, so an instruction to be "level abeam..." should be given if needed.

[aaaabbbbcccc1111]

It sounds like you had been transferred to TC before being given your direct, so TC should have made sure you were going to comply with the conditions set, so a phone call might have been made. I would hope that a pilot would check the new clearance if it was quiet on the RT, but regardless of what the book says, would just comply with the level by/abeam instruction if the RT was very busy.

[Lon More]

As stated earlier, done to death.
I always taught students that if they didn't want to fill in Airprox reports, restate any limitation on the clearance and repeated it and repeated it until it became second nature to them

[BrATCO]

The "level abeam" restriction should be given.
But when a "be leveled by XXX" clearance has been given, then "direct YYY" in an other message, I assume the ACFT has already been trimmed to descend at a given rate.
Why should this rate be changed ?

In the case of a leveled flight, when the pilot receives a direct, only the track is changed, not the rate of descent/climb : the cleared rate stays 0ft/min.

Or should we reiterate all the parts of the previous clearance in every massage ?
"Direct XXX. I confirm : maintain previously cleared level, keep previously cleared speed..."
"Climb FL370. I confirm : continue direct XXX, keep previously cleared speed, ..." :hmm:

This said, my second nature is to confirm the level restriction when it is needed.
In case of doubt, just ask.

[fireflybob]

I assume the ACFT has already been trimmed to descend at a given rate.

BrATCO, not necessarily!

If a VNAV PATH descent is being used when the new direct is given the "level abeam XXX" and the FMC is updated for the direct VNAV PATH will (assuming now low on path for next constraint after) go to a cruise descent of 1,000 ft/min.

If the "level abeam XXX" constraint still applies then the ABM Waypoints have to be selected and the constraint reentered.

Hope that makes sense!

Of course, other modes such as level change or vertical speed can be utilised as appropriate.

[BrATCO]

Thank you, fireflybob. :ok:

I already "intuited" that, now I know...
Own experience shows that constraints have to be repeated sometimes. Sometimes, there's no use...

I once had an wise English pilot (redundancy ?) departing from London.
On first contact, I told him : "Direct OKASI, climb FL 370, be leveled within 6 minutes".
His reply was : "Direct OKASI, climb FL 370, we'll be leveled abeam INPAX", which was (in other words) exactly what I meant.

This discussion leads me to ask a question I've had in mind for years :

- Among these clearances :
1 : Climb/Descend... be leveled by XXX
2 : Climb/descend... be leveled within x minutes
3 : Climb/descend... Minimum rate xxxx ft/minute

Which one(s) do pilots like/dislike most ?

[BOAC]

All three! Most of us can handle them all, although WITHOUT an EFIS map, 'level-by' a non-DME is more difficult.

[fireflybob]

- Among these clearances :
1 : Climb/Descend... be leveled by XXX
2 : Climb/descend... be leveled within x minutes
3 : Climb/descend... Minimum rate xxxx ft/minute

Which one(s) do pilots like/dislike most ?

Personally am not bothered either way by any of those options but the new breed of pilot can't wait to plug it all into the FMC (that way they don't have to think!) so number 1 : Climb/Descend... be leveled by XXX would be the best option in that case.

Even if you do get a "level by XXX" you can still use the picture on the map (what is known as the banana) and level change or vertical speed to achieve the constraint.

In short, an accomplished pilot will use all the "tools in the box" to best advantage to achieve the desired result. When I watch the way some pilots do it these days, I wonder how we did it with only VOR/DME, ADF and a chart! Happy Days!!

[BrATCO]

From my experience : most of the time (not all the time), constraints above a fix occur when there will be a communication transfer after said fix. Constraint is the result of a Letter Of Accordance (legal constraint for the controller). Changing the level over/abeam the fix means a co-ordination.
Missing a level constraint "abeam" after a direct can stuck next sector for the next hour : "If you can't send me the traffic at the right level, then send it on the right track"

Level constraints "within x minutes" will be delivered due to traffic.
In this case, changing the track by a direct or a vectoring might induce a "no more rate restriction" message.

Generally speaking, I reckon keeping the rate until said otherwise is a good way of doing things. Even though this procedure doesn't seem to be very instinctively, naturally, ergonomically easy to apply (if I understand fireflybob).

[fireflybob]

The other point I sometimes make to my new colleagues (!) is that these constraints are a limit and not a target - better to be down a few miles early (obviously not massively as there may be ramifications for fuel burn) rather than bust the limit - also say if you think you cannot make it, advise atc asap!

[BrATCO]

these constraints are a limit and not a target

Absolutely !

After a few "target" problems, my (personal) phraseology is now : "be leveled before XXX".
I don't mind pilots answering "by", but I watch their vertical path from a bit closer...

[BrATCO]

I personally don't like giving minimum rates to comply with constraints : it gives me the feeling of "driving" the plane, thus do the pilot's job, thus (maybe) upset him...

Silly, I guess... :bored:

[fireflybob]

We do see differences between States - hardly ever do UK give minimum/maximum rates of descent of "be out of FL XXX within Y minutes" which I notice does happen in France. In Germany you quite often get "1,500 per minute or more till passing FL XXX".

The one which can throw you occasionally is when you're used to a waypoint restriction and they the guy on the sector gives you a "by 80 DME before XXX) - used to happen on A25 northbound around Brecon - you plug it into the FMC or put it on the map only to find it's the same position as the waypoint!!

[BrATCO]

WITHOUT an EFIS map, 'level-by' a non-DME is more difficult.

Thank you, BOAC.
So I guess "in x minutes" is the easiest clearance for a non-RNAV flight.

Firefly,
funny this difference between states !
You're right : I use "be out of level XXX in less than Y minutes", actual rate at pilot's discretion...

Another method to get a good rate can be : " Continue present heading, climb FL XXX, when above FL xxx, direct...".
Usually, the pilot gives the best the plane can do. But it doesn't work everytime as this is only based on collateral effects : the rate is not part of the contract... :)

[5milesbaby]

fireflybob - thats the way we sometimes teach it unfortunately :ouch: If we have cleared you beyond the fix already, then it was common practice to give the new level restriction based on the fix/waypoint you are now tracking to. Regulars to the route may know and expect the usual restrictions, but it isn't so simple to all (and we have no clues if you actually are a "route regular" these days). From our point of view, its better to give you something that you are likely to read back correctly and save repeat transmissions.