A320 altitude constraint during climb

[Citation2]

Hello airbus drivers ,

It happens sometimes that in SID there are constraints at or below a certain altitude . So lets say shortly after take off at around 2000 ft or before acceleration altitude while still in SRS you have an altitude constraint at or below FL50 . And you are cleared to climb unrestricted to FL80.

So shortly after take off ,people usually put their head down into the FMGS and try to remove the alt constraint or ask the PNF to do so . ( sometimes even Speed ALT * is already reached by the time the guy clears the constraint )

If you pull open climb in SRS the aicraft starts accelerating before acceleration altitude which is not what we want.

I was thinking about the following option :

if in SRS actual speed is pulled (V2+10 ), the auto flight system will revert to open climb but it will still maintain the actual speed V2+10 . Which kind of simulates the SRS mode . SRS or open climb with V2+10 gives the same result. So noise abatement procedure is respected and the altitude constraint disregarded.

and then at acceleration altitude let's say 3000 AGL , manage the speed to accelerate to 250.

What do you think ? personally I think that going for a selected option for short term , by just pulling the speed , is a better option than a "managed option " by going into the FMGS shortly after take off to clear the constraint.

[Bula]

another two options:

1. Push EXP CLB

2. Delete the constraint from the FMGC and place it into the FCU window. Once cleared higher select a higher altitude.

[rudderrudderrat]

Hi Citation2

Or, set 8000 in window and don't do anything else apart from call "8,000 set". Above AA, set standard, pull for open climb and announce mode changes.

[HPbleed]

I tend to set the cleared altitude without pulling and wait until the aircraft engages in CLB. Nothing wrong with pulling open climb and pulling speed also to maintain v2+10.

[Citation2]

Just to emphasize that there s no need to pull both open climb and speed, by just pulling speed in SRS , you enter a reversion mode , and it automatically reverts to open climb while still maintaining V2+10

so it just costs just 1 pull and then 1 push at acceleration altitude

[MD83FO]

I agree citation, although it takes one second to clear an alt constraint on mcdu. When the pf pulls pulls speed while in srs the airplane makes an ugly pitch move as if it were out of trim.

Bula If you press exp climb the plane will accelerate to s speed but citation wants to fly srs right?

[Last Ditch]

Nice tip!! Only, don't pull out of SRS too early as you may loose some of the guidance protections SRS will provide... during EO conditions and windshear. (important when you operate hot, high and heavy).

[Young Paul]

I'm reluctant to ditch SRS below the level it would go anyway - if it were the same as Open Climb, they wouldn't have put it there at all.

My preference is: dial up the altitude on receipt, and pull for Open Climb at acceleration. I don't think there's an SOP, though.

[Last Ditch]

Yeah, but this post is about removing alt constraint that exists below accln alt (after takeoff without head down work)!!

[Microburst2002]

SRS has some in-built protections, but it is not magical. Unless you expect windshear, OPEN CLIMB works just fine.

In some models, all you have to do is pull speed, and then it will revert to OPEN CLB with selected speed.

Use FCU for tactical and MCDU for estrategical

[Young Paul]

Yeah, but this post is about removing alt constraint that exists below accln alt (after takeoff without head down work)!!

Okay, sorry for being pedantic, but can we be precise with language here? Is it possible to have an altitude constraint below acceleration altitude? The point about acceleration altitude is that you have to maintain a minimum gradient to that point - so an altitude constraint below there would undermine the basis of the acceleration altitude, no? Can you point me to a place where there is an altitude constraint below acceleration altitude? Or is that not what you meant?

Based on the question: "How do you remove an altitude constraint in the flightplan whilst you are still below acceleration altitude?" my answer is still, "Don't bother - wait till acceleration altitude and then take open climb - but that's not an SOP, just my preference." If non-essential ECAM actions can be delayed till the aircraft is clean, then I think non-essential FMGC work can be as well.

[Artificial Horizon]

In this situation where a constraint is below acceleration altitude I put the altitude constraint in the FCU and clear the constraint out of the FMGC. When clear higher just select it in the FCU and off you go. Avoids either crew having their head down during an important phase of flight. Just my opinion though, many ways to skin a cat!!

[sabenaboy]

@bula: "EXP CLB" is not present in the majority of A320's. And even in the A320's where you have it, it wouldn't be useful in the situation Citation2 is talking about

@rudderrudderrat: you said "set 8000 in window and don't do anything else" If you'd do that where there's an altitude constraint to cross a certain point at or below an altitude which is lower then your acceleration altitude, you would still see that constraint altitude in amber in the PFD. The A320 would make a very uncomfortable level of that constraint altitude while keeping a "V2 +10"-ish speed.

@md83FO: you said "When the pf pulls pulls speed while in srs the airplane makes an ugly pitch move as if it were out of trim." No it wouldn't. If you pull speed when the A320 is climbing at a constant managed speed, it would just keep the pitch to climb at the speed you were already climbing at.

At Young Paul: you asked "Is it possible to have an altitude constraint below acceleration altitude? The point about acceleration altitude is that you have to maintain a minimum gradient to that point - so an altitude constraint below there would undermine the basis of the acceleration altitude, no? Can you point me to a place where there is an altitude constraint below acceleration altitude? Or is that not what you meant?" I don't have charts with me here but it is either Lanzarote or Fuerteventura which has such (idiotic) SID's: cross a certain point a few miles away from the RWY at 3000' or below and continue climb thereafter. My company's standard SOP is to accelerate at 3000' AAL.

So, citation2, there's nothing wrong with your method in my opinion. It keeps your heads up and it's the fastest way to get the A/C doing what you want but it wouldn't work if your constraint is below acc. alt. In that case you would need to pull speed + pull open climb to avoid a level off at the constraint. Artificial Horizon's solution is also a good one: pre-departure, clear the constraint from the FMGC and put that altitude in the FCU.

Anyway, if I were approaching such a ridiculous alt constraint and told to maintain it, I would still be accelerating to 250 to smoothen the level off, even if I'm still below the (noise abatement) acc. alt.

Regards,
Sabenaboy

[rudderrudderrat]

@ sabenaboy:

If you'd do that where there's an altitude constraint to cross a certain point at or below an altitude which is lower then your acceleration altitude, you would still see that constraint altitude in amber in the PFD

Citation2's query was regarding one with an AA of 3,000ft and an initial climb restriction of FL 050.

[sabenaboy]

Originally Posted by rudderrudderrat

Citation2's query was regarding one with an AA of 3,000ft and an initial climb restriction of FL 050.

In that particular case, your solution is the best.