Levelling off above ATC cleared altitude on approach

[grrowler]

There has been some discussion at my place of work about the legality of levelling off for deceleration and configuring above your ATC cleared altitude. Eg you are cleared to 2500’/ cleared for the approach, but the FMS has a level decel at 3000’.

Can you fly the descent managed, levelling at 3000’ until approach slope intercept (normally 3 deg)!or must you force the aircraft down to the cleared altitude and intercept approach slope from there?

It is a bit pedantic in my opinion, but if anyone has any references it would be greatly appreciated.

[byrondaf]

Surely unless the approach procedure is prescriptive or when a CDA is required, I would say you can fly it how you like. ATC will always tell you if they want you to reach the platform by a certain point/distance etc. Plus some RNAV procedures are designed and coded as you describe...

[Check Airman]

Depends on the exact wording that's used, I'd imagine.

[Border Reiver]

I'll probably be shot down for being too simple....but isn't it as simple as the minimum rate of climb or descent in controlled airspace is 500fpm except for the purpose of acceleration or deceleration?

[Chesty Morgan]

I'll probably be shot down for being too simple....but isn't it as simple as the minimum rate of climb or descent in controlled airspace is 500fpm except for the purpose of acceleration or deceleration?
No it isn't.

[giggitygiggity]

Why do your colleagues need to decelerate so aggressively? If it is required, unless issued a minimum RoD then I can't see any issue. On our A320s, when selecting Flaps 2 you might get upto 800fpm climb as the flap comes out (poor FMGC logic), nobody ever seems to complain.

[grrowler]

Thanks, it’s not necessarily about aggressive decel, more the legality of flying the final descent into the approach as coded, which has the aircraft fly a level decel at an altitude above the ATC cleared altitude, which is also the commencement altitude of the approach. The proposed alternative is to either harden altitudes in the FMC to make the decel at 2500’, or fly a selected mode down to 2500’ prior to arming the approach. (A330 if it makes any difference)

Personally I can’t see a problem unless, as mentioned, you are given STANDARD RATE or some similar clearance, but I can’t find any reference to confirm either way.

[Fursty Ferret]

Common sense?

Levelling off at 5450ft in the vicinity of the airport to comply with a speed request is unlikely to make you friends with ATC. On the approach? Independent parallel approaches use different platform heights for obvious reasons so I'd be inclined to stick to it like glue to ensure separation.

On the other hand, if I'm already level at 3000ft on the localiser, decelerating nicely, and ATC offer a further descent to 2500ft and further with the ILS my inclination would be to remain level and intercept the glideslope from 3000ft in the spirit of our CDFA policy. Others might pay lip service and start a 200fpm descent towards 2500ft.

[sonicbum]

There has been some discussion at my place of work about the legality of levelling off for deceleration and configuring above your ATC cleared altitude. Eg you are cleared to 2500’/ cleared for the approach, but the FMS has a level decel at 3000’.

Can you fly the descent managed, levelling at 3000’ until approach slope intercept (normally 3 deg)!or must you force the aircraft down to the cleared altitude and intercept approach slope from there?

It is a bit pedantic in my opinion, but if anyone has any references it would be greatly appreciated.

Depends where You are, and often the answer will be found in the AIP Enroute section 1. As an example, for the UK :

3.2.2.4.1 In order to ensure that controllers can accurately predict flight profiles to maintain standard vertical separation between aircraft,
pilots of aircraft commencing a climb or descent in accordance with an ATC Clearance should inform the controller if they anticipate that their rate of climb or descent during the level change will be less than 500 ft per minute, or if at any time during such a climb or descent their vertical speed is, in fact, less than 500 ft per minute.

The above is complemented by the rules of CDO below 6000 ft where applicable.

[pilotnik]

There has been some discussion at my place of work about the legality of levelling off for deceleration and configuring above your ATC cleared altitude. Eg you are cleared to 2500’/ cleared for the approach, but the FMS has a level decel at 3000’.

Can you fly the descent managed, levelling at 3000’ until approach slope intercept (normally 3 deg)!or must you force the aircraft down to the cleared altitude and intercept approach slope from there?

First of all the "descent clearance" is not a clearance, it is an instruction and you have to obey. However, the approach clearance is in fact a clearance and you can execute it in a manner that fits your needs. You have every right to act as you desire unless you are regulated by ATC with IAS or VS, or unless it is specified otherwise in the AIP (Jepp, Navtech, Lido or whatever you have in the cockpit)

[172_driver]

It is a bit pedantic in my opinion, but if anyone has any references it would be greatly appreciated.

The best reference I could think of is the minimum rate of climb and descent requirements. But those are a bit academic and I can think of a dozen scenarios where it'd be prudent not to congest a busy frequency with that.

I know you're just looking for answers, but to me we are trying to solve a problem that doesn't exist. Typical pilot stuff to do.

[Roj approved]

AUStronauts at work again ggrowler, a firm grasp of the non essential.

For a laid back country, we sure are uptight, too many bush lawyers.

I'm pretty relaxed about all things, and at this phase of flight i believe it's more important to fly the profile that will get you where you want to be, company speed restrictions, configuration recommendations etc, than worry about these little issues. You're 10 miles from touchdown, it's going to make tenth fifths of f*@# all difference to the traffic pattern.

[Chesty Morgan]

Depends where You are, and often the answer will be found in the AIP Enroute section 1. As an example, for the UK :

3.2.2.4.1 In order to ensure that controllers can accurately predict flight profiles to maintain standard vertical separation between aircraft,
pilots of aircraft commencing a climb or descent in accordance with an ATC Clearance should inform the controller if they anticipate that their rate of climb or descent during the level change will be less than 500 ft per minute, or if at any time during such a climb or descent their vertical speed is, in fact, less than 500 ft per minute.

The above is complemented by the rules of CDO below 6000 ft where applicable.
That's en route not approach.

The 500fpm minimum (in the UK) is only a requirement above the transition altitude and in a hold.

[sonicbum]

That's en route not approach.

The 500fpm minimum (in the UK) is only a requirement above the transition altitude and in a hold.

My bad, I did not quote the entire paragraph.

[vilas]

. Eg you are cleared to 2500’/ cleared for the approach, but the FMS has a level decel at 3000’. what's the problem descending to ATC cleared altitude. Radar vector ATC ensures terrain clearence. Can you not be cleared for approach below or above level off altitude?

[Check Airman]

what's the problem descending to ATC cleared altitude. Radar vector ATC ensures terrain clearence. Can you not be cleared for approach below or above level off altitude?

Depends on where. Last time I was in South America, just this situation arose. "Unable"

[grrowler]

Vilas,
The clearance will normally be given through 5-6000’ - “Descend 2500’, cleared XX Approach”. I have always believed that from this point I could descend in whatever manner I sort fit (within all limits of course) to decelerate and configure, not below 2500 until established.

There is no problem with maintaining a continual descent to 2500 if I choose, but my question is whether I must.

[vilas]

Vilas,
The clearance will normally be given through 5-6000’ - “Descend 2500’, cleared XX Approach”. I have always believed that from this point I could descend in whatever manner I sort fit (within all limits of course) to decelerate and configure, not below 2500 until established.
There is no problem with maintaining a continual descent to 2500 if I choose, but my question is whether I must. Let's look at it from another angle. When a climb or descent clearance is given you may very ROC or ROD but a clearence to descend or climb doesn't include a level segment. For whatever reason you wish to leave off at another altitude in climb or descent should require ATC approval.

[Vessbot]

Is 500 fpm (with speed brakes of you're real close) not enough?

[tomuchwork]

I'll probably be shot down for being too simple....but isn't it as simple as the minimum rate of climb or descent in controlled airspace is 500fpm except for the purpose of acceleration or deceleration?

1000 fpm in France.....

And yes, you can configure, slow down, whatever. BUT - you need to descent to 2500ft eventually EXCEPT they tell you it is "pilots discretion", then it is, quiet logic, up to you. Not really rocket science....

[hans brinker]

Often in the US "cross XXX at or above AAA, cleared for the approach". Takes the guesswork out of it.

[FlightDetent]

There is no problem with maintaining a continual descent to 2500 if I choose, but my question is whether I must.
I think you should.

"Must" sounds like a lawyer's term and perhaps such exact rule, spelt out clear, will be impossible to find. An instruction to descend is exactly that and level flight does not fit that description.

An argument about a need to slow down for configuration change in level flight
- is a strawman since it can be done differently
- if it is short and temporary would not be a problem anyway.

Your example, in the opening post is benign. Let's blow it up while keeping it real:

- by ARINC definition the final app angle must extend in front of the FAF/FAP to enable capture from below, once established on the final track
- on many installations, this will create a pseudo G/S intercept quite far out, maybe from 5.5, 7000 feet (platform ALT 3000 let's say)

Once after the final vector, with clearance to descend 3000 and for the approach, one may wonder if maintaining the 6000 until the 3° is all right with everyone.

I think it is not, unless coordinated.

[grrowler]

So from what is being said on here, many (most?) approaches cannot be flown as coded because they will invariably have a level decel built into the profile at an altitude other than your ATC cleared level..(Airbus). I must/ should either modify the FMC to ensure it descends to the ATC level first, or select a mode giving a minimum of 500fpm descent to that point? If ATC asks you to reduce speed the best you can do is v/s-500fpm with full SPD BRK? IMHO, this doesn’t sound right and unnecessarily complicated... The reference earlier regarding acceleration and deceleration makes sense but I cannot find that reference in Aussie material as yet.

[vilas]

So from what is being said on here, many (most?) approaches cannot be flown as coded because they will invariably have a level decel built into the profile at an altitude other than your ATC cleared level..(Airbus). I must/ should either modify the FMC to ensure it descends to the ATC level first, or select a mode giving a minimum of 500fpm descent to that point? All approaches have FAF altitude or platform altitude. Generally the clearance is given to that altitude. Sometimes when the clearance is below that you should descend to that after confirming.The approach profile can be intercepted below FAF altitude without modification. In case of managed NPA it's not permitted to modify the FAF altitude.

[Chesty Morgan]

So from what is being said on here, many (most?) approaches cannot be flown as coded because they will invariably have a level decel built into the profile at an altitude other than your ATC cleared level..(Airbus). I must/ should either modify the FMC to ensure it descends to the ATC level first, or select a mode giving a minimum of 500fpm descent to that point? If ATC asks you to reduce speed the best you can do is v/s-500fpm with full SPD BRK? IMHO, this doesn’t sound right and unnecessarily complicated... The reference earlier regarding acceleration and deceleration makes sense but I cannot find that reference in Aussie material as yet.
No. You do not need to descend at 500fpm. You can descend at 50fpm if you're that worried about flying level.

[ManaAdaSystem]

No. You do not need to descend at 500fpm. You can descend at 50fpm if you're that worried about flying level.

In LHR they send you a letter if you fly a level segment before you intercept the glide. (Don’t ask me how I know ��) You may use a ROD down to 300 fpm to avoid this. Less than 300 fpm is considered level flight.

To the OP:
If you are cleared an altitude and also cleared approach, you should descend towards this altitude, not level off.
A level off at any other altitude may cause issues when you fly into airports with parallel approaches and two aircraft vectored for approach to different runways.
Follow the instructions from ATC. Easy!

[sonicbum]

In LHR they send you a letter if you fly a level segment before you intercept the glide. (Don’t ask me how I know ��) You may use a ROD down to 300 fpm to avoid this. Less than 300 fpm is considered level flight.

To the OP:
If you are cleared an altitude and also cleared approach, you should descend towards this altitude, not level off.
A level off at any other altitude may cause issues when you fly into airports with parallel approaches and two aircraft vectored for approach to different runways.
Follow the instructions from ATC. Easy!



If You are talking about CDA :

no segment of level flight longer than 2.5 nautical miles (nm) occurs below 6000ftQNH and ‘level flight’ is interpreted as any segment of flight having a height change of not more than 50ft over a track distance of 2 nm or more.

Hence, even 100 ft/min will work at typical terminal speeds.

[FlightDetent]

(Don’t ask me how I know ��) [...] Less than 300 fpm is considered level flight. Last time I did the calculation (do not ask me why:p) 100 fpm was enough, may have been a different airport.

Regardless, easy really does it. Follow the instructions honestly, speak up quickly if you cannot, and discard all bright ideas for great solutions out of the orderly flow.

Short version:https://cimg1.ibsrv.net/gimg/pprune.org-vbulletin/341x477/2019_08_30_182419_76b48c5deff33ffe9e65921af3f2f0e9eeb5155c.p ng

[ManaAdaSystem]

Last time I did the calculation (do not ask me why:p) 100 fpm was enough, may have been a different airport.

Regardless, easy really does it. Follow the instructions honestly, speak up quickly if you cannot, and discard all bright ideas for great solutions out of the orderly flow.

Short version:https://cimg1.ibsrv.net/gimg/pprune.org-vbulletin/341x477/2019_08_30_182419_76b48c5deff33ffe9e65921af3f2f0e9eeb5155c.p ng


300 fpm is what was said in the letter from LHR.

[grrowler]

https://cimg8.ibsrv.net/gimg/pprune.org-vbulletin/1741x235/f9c956d0_1a62_4423_9ac6_794c759f0ecf_666fbee53188cee3282715e 8ad75afc2ccedf354.jpeg
This is for a specific aerodrome, what are the actual general rules? I’m not talking about “I’m not really sure so I just fly 50fpm so I can’t get pinged either way”
https://cimg4.ibsrv.net/gimg/pprune.org-vbulletin/1164x731/b5d6cfb7_cd0d_418a_972e_ca467e538e54_ce35eb301526f901120946c 5be768048515aaaf1.jpeg
This is the scenario I originally described - we are saying this cannot be flown as coded? (Not talking about any modifications beyond FAF)

[Lookleft]

I think I know the situation the OP is referring to where an ALT CST* of 4000 is coded into the STAR but is not actually required when approaching the ILS from the east. If a pilot continues in managed descent then the aircraft will level off at the CST prior to intercepting the G/S instead of continuing the descent to 3000' which is the cleared level. In my view if ATC have cleared you to a specific level then that's the level you should descend to. They are not aware of how the FMS is coded and are not expecting you to level off. If you need to slow down to configure then select V/S so that the descent to the cleared level is maintained.

[parkfell]

As ATC use performance as one of the methods for standard separation, then if there is an aircraft performance requirement on the day to not perform in the anticipated manner, notify ATC, or agree with ATC a different course of action.
Ensure communication occurs. CRM includes ATC. Share the “mental model”.........one of the competencies of multi crew flying....l