A bystander here - question re: automatics and climbing for bus drivers...

[FirmamentFX]

Hi guys,

A procedural question if I may for any bus drivers (I'm working on the basis of the 32x but it is probably similar for the bigger jets too).

After takeoff, CLB is automatically engaged. Is this correct? Do you also have to *manually* engage the AP to engage NAV mode, or does it automatically engage at a certain altitude?

Then, in the climb phase, does the PF have to manually keep the AoA to whatever angle is proscribed, or is that then automatic as part of ALT or CLB (ie, at thrust reduction and accel altitudes is the pitch then automatic)? If the pitch has to be manually kept, surely that would disengage the any APs that are active?

Many thanks for your time.

Martin

[Diaz]

Not a driver, but from what I know, the levers are moved from the FLEX or TO/GA detentes to the CLB detentes to reduce to CLB power. You turn on either AP1 or AP2, then the bus flies itself for the climb, no intervention needed to maintain AoA. As for NAV mode- I believe it engages and will make the FD's move to follow the path above a certain altitude- but I'll let a bus driver tell you more.

[Hand Solo]

After takeoff, CLB is automatically engaged. Is this correct?

Yes, if the autothrust is armed.

Do you also have to *manually* engage the AP to engage NAV mode, or does it automatically engage at a certain altitude?

The autopilot has no influence on the NAV mode. NAV mode is a flight director function. It will engage automatically if armed at a preset altitude.

Then, in the climb phase, does the PF have to manually keep the AoA to whatever angle is proscribed, or is that then automatic as part of ALT or CLB (ie, at thrust reduction and accel altitudes is the pitch then automatic)?

Firstly there is no indication of angle of attack anywhere on the flight deck. You fly pitch attitudes. If you are manually flying then you follow the pitch attitudes indicated by the FD. If the autopilot is engaged you don't move the stick and the aircraft autopilot will control the pitch for you.

If the pitch has to be manually kept, surely that would disengage the any APs that are active?

Correct. Any movement of the sidestick whilst the autopilot is engaged activates the breakout and disengages the autopilot.

[Lemurian]

Quote : "After takeoff, CLB is automatically engaged."
NO, in normal OPS, with the FD on, autothrust and CLB are armed - A/THR and CLB are blue on the FMA. The PF selects CLB by pulling the T/Ls into the CLB detent, at the same time making the A/THR active.This happens at your selected "Thrust reduction altitude", at which you'll have a flashing "LVR CLB" reminding you to set the T/Ls into the CLB detent, thus activating the A/THR. A/THR will go white on the FMA.

Quote :"Do you also have to *manually* engage the AP to engage NAV mode, or does it automatically engage at a certain altitude?
"
No, NAV mode is armed during the take off and engages automatically at 30 ft, so that one could follow the SID manually. Engaging the A/P only means that it will take all the FD engaged/armed modes into account, as the modes are common for both FD and A/P.

Quote :"Then, in the climb phase, does the PF have to manually keep the AoA to whatever angle is prEscribed, or is that then automatic as part of ALT or CLB (ie, at thrust reduction and accel altitudes is the pitch then automatic)? "
After take off, the FD would give you an initial climb at V2+10 Kt or above, speed that you'll maintain with the FD bar until the end of the noise-abatement ; then the FD bar will propose a lower pitch angle in order to allow acceleration and cleaning-up after which a 250kt climb will be established.
The AoA requirements are translated for the pilot -whether flying or monitoring the A/P - into speed schedules and FD/Ap commends.

Quote :"If the pitch has to be manually kept, surely that would disengage the any APs that are active?
"
You could, if you wished, engage the A/P as soon as 5 seconds after lift-off or 30 ft radio height. in this case, the A/P will do a very good job of maintaining the climb parameters of the day. No need for human intervention. On the other hand, if you elect to fly manually with the FD, the command bars will give you the optimum performance for your take off segments.

[TyroPicard]

Aren't Airbus pilots wonderfully polite? You ask a question about driving a bus and they tell you all about aircraft!

Cheers
TP

[FirmamentFX]

Thank you very much everyone! That is really useful.

So I'm thinking that I got my wires crossed - NAV is therefore NOT an automatic flight mode - it is (as Hand Solo mentioned) an FD function (and therefore provides the "bars" on the PFD for the PF to fly?)

After take off, the FD would give you an initial climb at V2+10 Kt or above, speed that you'll maintain with the FD bar until the end of the noise-abatement

Thanks Lemurian - is there ever a situation where V2+10 (or the initial climb speed) would be greater than the speed for the selected flaps configuration, so that it would be necessary to clean up earlier in the climb?

Thanks again,

Martin

[Lemurian]

Quote : "NAV is therefore NOT an automatic flight mode - it is (as Hand Solo mentioned) an FD function (and therefore provides the "bars" on the PFD for the PF to fly?)"
NO ! As said earlier, the FMGS is comprised of several parts : The FD and the AP share the same modes. When you switch from FD flying to A/P engagement, the A/P takes all the modes that you are using at its engagement.The FD command bars do not change. On the FMA, one line is added over the FD status : AP1 0r 2 over 1 FD 2 in normal OPS.

Quote :"
"...is there ever a situation where V2+10 (or the initial climb speed) would be greater than the speed for the selected flaps configuration, so that it would be necessary to clean up earlier in the climb?"...
No. It never does. On the 'BUs (hello, TP ! :) ), the flap selections are shown on the speed tape and give you the margins with the Vfs.

[FirmamentFX]

Thanks for clearing that up Lemurian :) I think I've got it now :ok:

Martin

[TyroPicard]

Just in case you haven't...
The Guidance bit of the FMGC output, in all vertical and horizontal modes, goes to the FD bars and to the AP. If you are hand-flying, following the FD will give the required a/c performance. If you engage the AP it follows that guidance for you, and you make sure it's doing it right by monitoring the FD and the a/c performance.
TP