A320 noise abate T/O

[Idunno]

In my outfit, on the A320, we have the CLB THRUST altitude set to 1500' agl and the ACCEL ALT set to 3,000' agl.

The two used to be set to the same alt (1500') but it was changed a while back.

The occasion now arises where you are on a SID with a cleared altitude of (say) 5,000' and on departure ATC give you a clearance to climb to (say) FL140 when passing 1,000'.

You duly set 14,000 in the ALT window....but then what?

If you 'Pull ALT' the a/c will immediately start a low level acceleration in THRUST CLB/OPEN CLB...ignoring the noise created by dropping out of SRS mode early.

Alternatively you can remain in SRS mode by not pulling the ALT knob...however the a/c will target a 5,000' level off if that is in the FPLAN as a constraint (as a normal part of the SID).

Our Chief Instructors instruction is to set 14000 and PULL ALT immediately...his reasons...your cleared alt is 14,000 and it is SOP to target the cleared alt, not some other....and also, ATC having changed the SID it is now cancelled.

Of course this ignores the noise issue.

Any thoughts?

[strikerA320]

Your Instructor might be right in a sense, but
there are some airport that you should comply with the initial constrained departure altitude even when cleared to a higher altitude.
If I were the one flying, I will just pre-set the altimeter to FL140, so as to comply with the noise abate proc., then clean-up, approaching 5000' confirm with ATC if you're still to comply with the altitude restriction; when cleared, just pull alt sel and have that "Thrust Clb/ Open Clb" read out.
I think with this, you complied with all the Dept Alt constraint.
Accel at 3000', 5000' initial alt constraint and the cleared alt of FL140.

[Idunno]

I agree...I don't like this idea of 'pull ALT' as soon as you get the higher clearance. Obviously (as you say) besides the noise issue there's the fact that you might not make a critical altitude constraint due to accelerating low level.

There is another alternative.

Set the newly cleared altitude in the window and then PUSH ALT.

What do you think of that idea?

[Phoenix_X]

Good idea, but it has thesame result. The mode will change to CLB, just as it would normally do at acceleration altitude. The aircraft will still want to start accellerating.

[Idunno]

You sure about that Phoenix?
I haven't tried it, but I thought PUSH ALT would continue with a normal climb profile as set up in the box.

Need to try it in the sim I think.

[3 Point]

Am I missing something here? What's wrong with pulling speed, setting 14,000ft and pulling alt then pushing back to managed speed on passing 3,000?

[Idunno]

Well for a start, if you pull speed you exit SRS mode.
Not a perfect solution.

Also I think it gets a bit complicated...too many actions in a high workload scenario.
Is that the SOP your company uses?

I know - its possibly better than starting an immediate acceleration (by pulling ALT), but its still less than ideal.

[3 Point]

Yes, of course you exit SRS but the object of the exercise is to climb at a set speed (V2 +10 or whatever) to 3,000' while still setting a climb to 14,000'. Pulling speed will put you in selected speed at the current ias which can then be fine tuned if required.

Our SOP do not cover this exact situation, it's one of those times when you use the most appropriate modes to achieve the required aim; in this case a continuous climb at a selected speed (who cares if it's selected on the FCU or by raising the aa in the PERF page or by setting a speed constraint at a down route waypoint) to a selected altitude.

I suppose SRS might be a good thing in a windshear scenario but here I'd let it stay in SRS, set 14,000' and if we entered ALT CST* before I had time to pull the alt knob after 3,000' too bad.

[Phoenix_X]

Idunno, I've seen it happen several times, it definitely happens on our A320s. Basically pushing the ALT engages managed CLB, even when you're below accel. altitude.

[Captain Scarlet]

How about PF sets 14000 and asks PNF to delete the constraint from the flight plan? It should take PNF two button presses on the MCDU to delete the constraint. This will give 14000 as the target alt but leave you in SRS mode until 3000.:ok:

[Phoenix_X]

Now that's the way I do it :ok:

[3 Point]

Cap Scarlet

Your method will work but I have two reservations. First; if the constraint is both speed and alt you can't just delete it! Second; when I'm PF and I ask PNF to alter the FLT PLN I like to cast an eye over what he's doing just to check. Remember we are talking about a change of clearance passing 1,000' so, all this will take place in the midst of thrust reduction and flap retraction which is not a good time for both pilots to be focussing on the MCDU.

On the whole I prefer to use the FCU for short term changes to the flight path as it's easily monitored by both pilots and only one pilot (PF) is making changes to the aircraft flight path. If the constraint to be deleted was say at FL190 and the revised clearance was to FL280 then your method is fine.

I guess it's horses for courses!

[FlapsOne]

Guys

Please don't lose sight of the blindingly obvious here.

Just 'cos ATC tell you something at 1000' doesn't mean (and never has meant) that you have to action it at 1000'.

Deal with it however you like, even scribble it down and read and do it later, but the noise abate is there for a reason. Do the other stuff when it needs to be done.

Idunno
Ask you Chief Instructor what you should do if the instruction were prefixed "..after noise procedure, climb FL140........."

[Aztec Kid]

If you line select the right hand MCDU key for the fix with both the speed and altitude constraints, the VERT REV page for that fix will open. You then have the option to clear only the altitude constraint, leaving the speed constraint in place. I would have the PM accomplish this task. If you are the PF and you feel task saturated, engage the A/P. Then you should be able to monitor the PM's MCDU inputs, or simply enter them yourself. Unless you are extremely light and at TOGA Thrust, you should have plenty of time to clear the constraint prior to ALT CSTR*.

Best regards,
The Kid

[OPEN DES]

hi guys!
what about changing all altitude constraints for the climb phase during the cockpit preparation to ´at or above´ constraints. you ll always have the cleared or constrained (whichever is lower)altitude in the FCU anyway. in amsterdam the same happens more or less. the SID is coded to have an ´at FL060´ constraint when joining the airway. after T/O ATC will most of the times clear you to FL090 when passing 2000 feet (=before ACC HT of 3000). you avoid an unwanted level off in ALT CST by changing the constraint to ´+FL060´. Initially you will always have FL060 in the FCU to comply with the constraint and the initial cleared FL, which are the same in amsterdam. in the boeing you ll find exactly the same problem. most operators that i know of which fly out of AMS use the method of changing the alt. constraint during the FMS preparation.
my 2 cts
ciao
S.