Manually overriding autothrust

[vilas]

Dozy
FCU ATHR and AP buttons are used to engage while ID buttons are used to disengage.

[vilas]

CONF iture, RRR, Altcrznav
I was surprised to read the following in the latest FCOM. Read the first condition. There seems to be a modification. So with this MOD the ATHR can be just clicked of without thrust increase to climb. Sensible I would say.

Applicable to: 18-CMHE, 18-IMHE

TheThrust Lock function is activated when the thrust levers are in the CL detent(or the MCT detent withone engine out), and:

‐ The flight crew pushes the instinctive disconnect pb onthe thrust levers, or

‐ The flight crew pushes the A/THR pb on the FCU, or

‐ The A/THR disconnects due to a failure.

The thrust is locked at its level prior to disconnection. Moving the thrust leversout of CL or MCT suppressesthe thrust lock and gives the flight crew manual control with the thrust levers.
The next para is
Applicable to: 18-CMTE, 18-CMTEH, 18-CUHE, 18-CUTE, 18-CUTEH, 18-IMTE, 18-IUHE, 18-IUTE


Here the first line is missing.

[Capn Bloggs]

There seems to be a modification. So with this MOD the ATHR can be just clicked of without thrust increase to climb. Sensible I would say.

Correct. That's why Boeings have always done it that way.

[Uplinker]

I must admit to a bit of misunderstanding regarding AT and bumping it into MCT.
While enroute, I bumped the levers out of CLB and into MCT thinking I'd lose AT as well and I didn't. The EPR started climbing, obviously, and putting them back into the CLB detent returned everything to normal.

It was as dramatic a shift in automation levels - more of a hybrid change! but it was easily returned to the previous level.

Yes, the point is when the thrust levers are moved forward out of the CLB detent, 2 things happen:

1. The thrust goes that commanded by the actual thrust lever position,*

2. Autothrust disengages - but REMAINS ARMED, (unless you are below 100'). So if you then return the thrust levers to the CLB gate, autothrust will re-engage. (This was how phase advance worked, but it was very poorly taught and therefore very poorly understood by most pilots, who then got it wrong).



*A slightly fuller description: With the thrust levers in the CLB gate and auto-thrust engaged, the auto thrust will vary engine power as required between idle and CLB power. It does not backdrive the thrust levers, which do not therefore move, but one can easily imagine the 'virtual' thrust levers moving between idle and CLB and see it on the EWD gauges. When one pushes the thrust levers forward of the CLB gate, the auto-thrust dis-engages and the FADECs increase power from what might have only been idle, to the thrust commanded by the actual lever position. This could be a very large increase if it got all the way to above CLB power from idle, so phase advance was just intended to be a second or so out of the CLB gate and back in again. This would start accelerating the engines towards CLB, giving the speed increase required, but after that second, putting the levers back to the CLB gate to re-engage autothrust, which would then return the engines to idle. 'Click out' - 'click back' in, in about the time it takes to say that, is all that was needed.

PS
If you pull the thrust levers back from CLB, I think the auto-thrust stays engaged, but the engine thrust would then limited between idle and the new thrust lever position. I guess this would be so one could instinctively reduce power in the event of an overspeed I suppose?, but I've never done it that way. (The ECAM would ask you to return the levers to CLB soon after - giving it control of the full range again).

[CONF iture]

Originally Posted by vilas

There seems to be a modification. So with this MOD the ATHR can be just clicked of without thrust increase to climb.

Then it is another new thing, but not applicable to all, another matter for confusion. 25 years later still modifying something that was supposed to be simple ...

Thanks for the information.

[BARKINGMAD]

What do pilots do these days?

F A D E C.
Grumpy old F/E in Classic 747 assured me we had FADEC on the -100/200 series.

Fingers

All

Direct

Engine

Control

*"@§'ing USE them if you have to!!??

"Me first. No wonder those beggars over the Atlantic didn't know what was going on... Is that an aeroplane you guys are flying.....?"

Thanks Capt Bloggs, your comment SEZ IT ALL!!!!

[vilas]

Captbloggs and BARKINGMAD
China Airlines 747SP suffered flameout on NO.4 at 41000ft with AP on, no big deal really ( I was 747 Capt). The capt. did a barrol roll and in few seconds lost 30000ft. Had it been at 30000ft it would have met the same fate as AF447. He was flying a real aeroplane not a FBW. He was an experienced captain and not a rookie copilot. Nobody blamed 747. Things happen you know.

[bubbers44]

Some stupid pilots get lucky, some don't. Learn to really fly, then fly. Even stupid pilots can do stupid things and get lucky and not crash. Others aren't quite so lucky so everybody dies. AF 447 was one of those.

[bubbers44]

I saw that twisted up 747 at SFO for quite some time. Quite impressive of his ability to recover from a roll because an engine failed and he didn't follow any procedures. He is probably his home town hero. They probably don't know how to fly either.