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-   -   Airbus high speed protection (https://www.pprune.org/tech-log/586640-airbus-high-speed-protection.html)

roofdog 6th Nov 2016 00:07

Airbus high speed protection
 
What happens if in the cruise (auto pilot engaged) you apply TOGA thrust? High speed protection should engaged and auto pilot disengage....nose pitch up to prevent overspeed? Then what eventually reduces the thrust, assuming it's left in TOGA?

Thanks

KayPam 7th Nov 2016 01:35

Hi
I dont know any engine protection which would reduce to mct.
However, the high speed prot will induce a climb to reduce speed

mcdhu 7th Nov 2016 15:10

TOGA is TOGA and there's nothing the A/Thr can do about it.

Nick 1 7th Nov 2016 15:36

Setting TOGA after FLX/MCT a/thr will disconnect and revert to armed , i think protection will add nose up a/p disconnect ,with TOGA until power is manually reduced , in this scenario.

vilas 7th Nov 2016 17:03

won't disconnect but will become armed from active and will remain so.

tdracer 7th Nov 2016 17:56

Not sure about Airbus (although I'd be mildly surprised if it's different), but on Boeing TOGA isn't defined outside of the Takeoff envelope (above 250 knots and 15k-17k altitude, depending on the aircraft model).
Above that, full forward throttle gives Max Con.

SADDLER 8th Nov 2016 00:01

Hi
Nothing happens, except for toga flashing in white.

vilas 8th Nov 2016 00:56


Originally Posted by SADDLER (Post 9570787)
Hi
Nothing happens, except for toga flashing in white.

why will it flash? It will only show MAN TOGA

FlightDetent 8th Nov 2016 09:11

Maybe he ment LVR CLB? With A/THR armed, it is not beyond my imagination ...

SADDLER 8th Nov 2016 12:54

Hmmm
As as far as I can remember it was toga flashing in white.
Could be wrong.

SloppyJoe 8th Nov 2016 13:31


Then what eventually reduces the thrust, assuming it's left in TOGA?
Hopefully the idiot siting in the seat at the front will reduce it, after seeing what happens if he does this to see what will happen.

vilas 8th Nov 2016 13:42


Originally Posted by FlightDetent (Post 9571131)
Maybe he ment LVR CLB? With A/THR armed, it is not beyond my imagination ...

FD for lever climb to flash you need THR RED altitude. It cannot happen at in cruise phase.

sonicbum 8th Nov 2016 13:47


Originally Posted by roofdog (Post 9568517)
What happens if in the cruise (auto pilot engaged) you apply TOGA thrust? High speed protection should engaged and auto pilot disengage....nose pitch up to prevent overspeed? Then what eventually reduces the thrust, assuming it's left in TOGA?

Thanks

Protections have been designed considering the fact there are 2 rated and proficient pilots at the controls. Hopefully, like it has already been mentioned, at least 1 will think about reducing the thrust like when you're in the car on your way to the airport called from stby and you lift your foot off the pedal when you see the cops.

vilas 8th Nov 2016 14:42

tdracer

but on Boeing TOGA isn't defined outside of the Takeoff envelope (above 250 knots and 15k-17k altitude, depending on the aircraft model).
Above that, full forward throttle gives Max Con.
In airbus chart TOGA is given up to FL145. But MCT and MAX CLB are given up to FL390 but the difference between them is of the order of .3/.4 %N1. At cruise level TOGA and MCT should be same.

FlightDetent 8th Nov 2016 23:23


lever climb to flash you need THR RED altitude. It cannot happen at in cruise phase.
Oh yes it can. DSC-22_30-100 "B" LVR CLB flashing white - Request to set the thrust levers in CL detent in the case not in position while the aircraft is above the altitude of thrust reduction with both engines running.

Whenever the A/THR is armed and the TLs are not in the CLB detent, you'd get told by the aircraft they're not where expected. The first instance is passing ACC ALT in after take-off, indeed.

vilas 9th Nov 2016 04:25

FlightDetent

Oh yes it can. DSC-22_30-100 "B" LVR CLB flashing white - Request to set the thrust levers in CL detent in the case not in position while the aircraft is above the altitude of thrust reduction with both engines running.
The discussion is about cruise phase with thrust levers in TOGA. You have transited TO phase and you are not in GA phase. There is no thrust reduction altitude in cruise.The statement you have quoted is not applicable in cruise phase.

sonicbum 9th Nov 2016 05:20


Originally Posted by vilas (Post 9572126)
FlightDetent

The discussion is about cruise phase with thrust levers in TOGA. You have transited TO phase and you are not in GA phase. There is no thrust reduction altitude in cruise.The statement you have quoted is not applicable in cruise phase.

Correct. In addition with 2 engines running past the CLB detent you are out of the A/THR active zone so the system lets you use any other thrust setting position you may require (MCT or TOGA) although as stated before the increase in thrust specifically at high altitude is minimal.

Groundloop 9th Nov 2016 08:32

I may be wrong but I thought I read somewhere that Airbus modified the logic in the A380 and A350 and overspeed protection on these aircraft does reduce thrust automatically.

Can anyone confirm this or tell me I'm wrong?

vilas 9th Nov 2016 09:02

Up to A330 when ATHR is blue there is no protection. But with ATHR active may be in THR CLB or THR IDLE and if you do not fly FDs properly and speed reaches either MAX speed or drops below VLs the FMA is removed and ATHR reverts to speed and managed speed target changes to selected to recover the speed.

Gryphon 9th Nov 2016 17:46


Up to A330 when ATHR is blue there is no protection
Agree, except alpha-floor.


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