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Airbus planes seeming to switch off engines on hold pattern

Posted: Sun Feb 28, 2021 6:55 am
by Darkchild101
Twice I have been on Airbus aircraft, a 330 approaching Johannesburg and then a 350 getting into Edinburgh. When approaching the airport and doing turns the aircraft/pilots seemed at times to have switched off the engines and then switched them on again. Probably not what happened but the plane seems to go quiet and then then sound of engines comes on again

On the Johannesburg flight on Turkish Airlines we were in a pattern hold for what seemed forever and I felt passengers were getting anxious with the constant sound of engines on and off again. Obviously we were in good hands but it can be nerve wrecking. On Johannesburg flight it seemed to last about 10 minutes

Do pilots switch engines off sometimes during a pattern hold?

Sorry if its a silly question

Re: Airbus planes seeming to switch off engines on hold pattern

Posted: Sun Feb 28, 2021 7:17 am
by gloom
Impossible.

What you refer to, is most likely just a thrust reduction managed by auto-throttle system. When speed is managed (and while in hold, there's usually constant speed requirement), during turns plane tends to move up/down a bit. And throttles will then adjust thrust to maintain speed as set. This effects in engine noise quite much. During flight, at low engine revs it tends to "hide" in the noise of air running around, then, once the plane needs to accelerate again, the engines will go back to noise with rising revs. That's why sometimes the engines will go loud, then get "switched off". They are not, they're just "ordered" to reduce thrust, revs, and go quiet (enough), out of surrounding noise.

Cheers,
Adam

Re: Airbus planes seeming to switch off engines on hold pattern

Posted: Sun Feb 28, 2021 7:50 am
by Starlionblue
Airliners glide very well. If we're slowing down or going down, it is frequently at idle thrust. The engines will be pretty much inaudible from the cabin.

Nitpicks.
- It's autothrust on Airbus, not authothrottles.
- It's thrust control, not throttle.

:old:

Re: Airbus planes seeming to switch off engines on hold pattern

Posted: Sun Feb 28, 2021 8:43 am
by zeke
Holds often have aircraft descending, which would be at idle thrust, if they need to level off thrust will come back up to maintain speed.

Re: Airbus planes seeming to switch off engines on hold pattern

Posted: Sun Feb 28, 2021 10:33 am
by gloom
Starlionblue wrote:
- It's autothrust on Airbus, not authothrottles.
- It's thrust control, not throttle.


I stand corrected. :white: Thanks.

Cheers,
Adam

Re: Airbus planes seeming to switch off engines on hold pattern

Posted: Sun Feb 28, 2021 1:00 pm
by Woodreau
The only operator that I know of that secures engine(s) inflight is the military. p-3 crews will routinely secure an engine to extend on station patrol time.

airlines do not secure engines inflight unless it’s an emergency.

Re: Airbus planes seeming to switch off engines on hold pattern

Posted: Sun Feb 28, 2021 2:41 pm
by Starlionblue
gloom wrote:
Starlionblue wrote:
- It's autothrust on Airbus, not authothrottles.
- It's thrust control, not throttle.


I stand corrected. :white: Thanks.

Cheers,
Adam


No worries. Just nitpicking.

The military calls them throttles.

Consistent inconsistency that we can dissect is what we live for. :biggrin: :box: :hissyfit:

Re: Airbus planes seeming to switch off engines on hold pattern

Posted: Sun Feb 28, 2021 10:36 pm
by Darkchild101
Starlionblue wrote:
Airliners glide very well. If we're slowing down or going down, it is frequently at idle thrust. The engines will be pretty much inaudible from the cabin.

Nitpicks.
- It's autothrust on Airbus, not authothrottles.
- It's thrust control, not throttle.

:old:



Thanks for the explanation

Re: Airbus planes seeming to switch off engines on hold pattern

Posted: Sun Feb 28, 2021 10:37 pm
by Darkchild101
gloom wrote:
Starlionblue wrote:
- It's autothrust on Airbus, not authothrottles.
- It's thrust control, not throttle.


I stand corrected. :white: Thanks.

Cheers,
Adam


Thanks

Re: Airbus planes seeming to switch off engines on hold pattern

Posted: Tue Mar 02, 2021 4:37 am
by BoeingGuy
Starlionblue wrote:
gloom wrote:
Starlionblue wrote:
- It's autothrust on Airbus, not authothrottles.
- It's thrust control, not throttle.


I stand corrected. :white: Thanks.

Cheers,
Adam


No worries. Just nitpicking.

The military calls them throttles.

Consistent inconsistency that we can dissect is what we live for. :biggrin: :box: :hissyfit:


Boeing calls them “thrust levers”. However, it’s still called the Autothrottle.

Re: Airbus planes seeming to switch off engines on hold pattern

Posted: Tue Mar 02, 2021 5:57 am
by Starlionblue
BoeingGuy wrote:
Starlionblue wrote:
gloom wrote:

I stand corrected. :white: Thanks.

Cheers,
Adam


No worries. Just nitpicking.

The military calls them throttles.

Consistent inconsistency that we can dissect is what we live for. :biggrin: :box: :hissyfit:


Boeing calls them “thrust levers”. However, it’s still called the Autothrottle.


I've been curious about the origins of Boeing's inconsistent naming convention for a long time.

My hypothesis: Given that engine power control predates jet engines, autothrottles were used to control actual throttles on piston engines. The name then carried over to jet engine thrust control.

Ironically the first automatic power control was on a jet, the Me-262 Schwalbe. The first commercial application was for the DC-3 though, a piston.

Re: Airbus planes seeming to switch off engines on hold pattern

Posted: Tue Mar 02, 2021 6:21 am
by T54A
To add to above explanations, an A330/350 pilot, or any other airline pilot for that matter, would never switch off a normally operating engine in flight other than in an emergency. It would be considered a massive breach of procedure and a safety event. This is especially true in a two engine aircraft.

Re: Airbus planes seeming to switch off engines on hold pattern

Posted: Tue Mar 02, 2021 9:37 am
by flipdewaf
T54A wrote:
To add to above explanations, an A330/350 pilot, or any other airline pilot for that matter, would never switch off a normally operating engine in flight other than in an emergency. It would be considered a massive breach of procedure and a safety event. This is especially true in a two engine aircraft.


Very off topic however..

A friend of my parents who (who shall remain nameless) was an ex-vulcan and Virgin 747 pilot used to fly his kit plane over our house (and others I assume) turn the engine off and shout greetings at us as he descended to about 100ft then turn the engine back on and be on his way, incredibly fun for me and my brothers but would make my mother go mad. He had landed in our fields occasionally and when I spoke to him recently about the turning engine off he said if it hadn't restarted he was always lining up to go in to the long field anyway.

Fred

Re: Airbus planes seeming to switch off engines on hold pattern

Posted: Tue Mar 02, 2021 11:10 am
by Flow2706
T54A wrote:
To add to above explanations, an A330/350 pilot, or any other airline pilot for that matter, would never switch off a normally operating engine in flight other than in an emergency. It would be considered a massive breach of procedure and a safety event. This is especially true in a two engine aircraft.

When I was a new FO one Captain told me that he once noticed a dropping oil level on one engine. He said he elected to shut down the engine before it reached a very low level, he restarted the engine before the approach and therefore avoided landing single engine. Not sure if his story is true or if he just made it up (it's in violation of the Airbus procedures anyway - if only the quantity is low there is no procedure to shut down the engine on A320, it's only necessary when the pressure drops as the low quantity indication without any other signs of problems could just be an indication problem)

Re: Airbus planes seeming to switch off engines on hold pattern

Posted: Tue Mar 02, 2021 2:25 pm
by Starlionblue
Flow2706 wrote:
T54A wrote:
To add to above explanations, an A330/350 pilot, or any other airline pilot for that matter, would never switch off a normally operating engine in flight other than in an emergency. It would be considered a massive breach of procedure and a safety event. This is especially true in a two engine aircraft.

When I was a new FO one Captain told me that he once noticed a dropping oil level on one engine. He said he elected to shut down the engine before it reached a very low level, he restarted the engine before the approach and therefore avoided landing single engine. Not sure if his story is true or if he just made it up (it's in violation of the Airbus procedures anyway - if only the quantity is low there is no procedure to shut down the engine on A320, it's only necessary when the pressure drops as the low quantity indication without any other signs of problems could just be an indication problem)


Wow. At least get an ECAM telling you to shut it down before you do. :D

I don't know the A320 but on the A330 and A350 a zero oil indication doesn't mean you don't have any oil left.

Re: Airbus planes seeming to switch off engines on hold pattern

Posted: Tue Mar 02, 2021 3:35 pm
by GalaxyFlyer
If you call it a “flight deck”, you might use “thrust levers”.

Re: Airbus planes seeming to switch off engines on hold pattern

Posted: Thu Mar 18, 2021 5:47 pm
by N1120A
Throttles = Piston
Power = Turboprop
Thrust = Jet.

In reality, it really doesn't matter. Throttle is a genericized term meaning that which modulates power produced by an engine. Going on about it is pedantic.

No one turned off an engine on your flight, unless one broke.