A320 TOGA Efficiency

[spuncy]

Hi folks,
First of all I would like to apologies for asking this silly question. But it just keep bothering me.
I am wondering at what Flight Level or Altitude TOGA Thrust will be in-efficient? Since I could not find the answer on FCOM
As EXP CLIMB it stated it's not recommended to use that mode after passing FL 250 (If I am not mistaken).

Thanks for your help guys.

[sonicbum]

Originally Posted by spuncy

Hi folks,
First of all I would like to apologies for asking this silly question. But it just keep bothering me.
I am wondering at what Flight Level or Altitude TOGA Thrust will be in-efficient? Since I could not find the answer on FCOM
As EXP CLIMB it stated it's not recommended to use that mode after passing FL 180 (If I am not mistaken).

Thanks for your help guys.

What You are asking is not very clear, at least for me. Are You asking how much does thrust decrease with increasing altitude and its effects on rate of climb or something like that ?

[spuncy]

Originally Posted by sonicbum

What You are asking is not very clear, at least for me. Are You asking how much does thrust decrease with increasing altitude and its effects on rate of climb or something like that ?

Apology sonicbum, what I am trying to ask is in high altitude will there any significant impact if I required more thrust by setting to TOGA in order to gain more rate of climb.

[sonicbum]

Originally Posted by spuncy

Apology sonicbum, what I am trying to ask is in high altitude will there any significant impact if I required more thrust by setting to TOGA in order to gain more rate of climb.

Short answer : absolutely no. For a detailed answer we need some data from the engine and examine the thrust output variations graph according to all the different parameters taken into account by the FADEC.

[TopBunk]

What circumstances would require you to need extra thrust?

To gain extra ROC you can trade airspeed/Mach for a (short) while. Anything else could and maybe should require a call to ATC saying 'unable' or a request for descent.

[spuncy]

Originally Posted by sonicbum

Short answer : absolutely no. For a detailed answer we need some data from the engine and examine the thrust output variations graph according to all the different parameters taken into account by the FADEC.

Thanks for your info

[spuncy]

Originally Posted by TopBunk

What circumstances would require you to need extra thrust?

To gain extra ROC you can trade airspeed/Mach for a (short) while. Anything else could and maybe should require a call to ATC saying 'unable' or a request for descent.

TopBunk at this point I only come out from scenario that I am accidentally flying into a missile area where I have to reach certain Altitude to avoid those missile. For example I am cruize at FL 290, and as per notam Minimum flying is FL 360, where deviate is not an option.

Sorry for the confusion, I am just curious. Not planning to experience it in real life.

[Fursty Ferret]

A u-turn would be an easier option...

Although expedite climb is not recommended, if you desperately want to get height quickly it's likely the best option as it'll trade all your excess energy for altitude.

I think you might be misjudging the severity of the notam though, which is really for discouraging routine flight within missile range. After all, if you had a depressurisation or engine failure you're going to end up down there anyway.

[pineteam]

Originally Posted by spuncy

Apology sonicbum, what I am trying to ask is in high altitude will there any significant impact if I required more thrust by setting to TOGA in order to gain more rate of climb.

At high altitude, TOGA = CLB thrust so I don’t see any issue. Just remember to retard the levers back to CLB detent to regain A/THR to avoid an overspeed.

[FlightDetent]

Perhaps the question can be rephrased.

What is the limiting altitude, where the engine is no longer capable to provide any more than MAX CLB thrust, and so moving the thrust levers beyond the CLB detent yields no reaction?

Top of my head, I do not know. The feeling is maybe as low as FL170, but that's just a shot in the dark. It had been discussed before.

[tdracer]

Originally Posted by FlightDetent

Perhaps the question can be rephrased.

What is the limiting altitude, where the engine is no longer capable to provide any more than MAX CLB thrust, and so moving the thrust levers beyond the CLB detent yields no reaction?

Top of my head, I do not know. The feeling is maybe as low as FL170, but that's just a shot in the dark. It had been discussed before.

It varies a bit between different aircraft and engine types, but the takeoff envelope is typically defined up somewhere between 15k and 18k, and airspeed up to around Mach 0.5. Go faster than that, and/or higher than that, and pushing the throttles beyond max climb doesn't do anything.

[spuncy]

Originally Posted by FlightDetent

Perhaps the question can be rephrased.

What is the limiting altitude, where the engine is no longer capable to provide any more than MAX CLB thrust, and so moving the thrust levers beyond the CLB detent yields no reaction?

Top of my head, I do not know. The feeling is maybe as low as FL170, but that's just a shot in the dark. It had been discussed before.

Thanks FlightDetent

[spuncy]

Originally Posted by tdracer

It varies a bit between different aircraft and engine types, but the takeoff envelope is typically defined up somewhere between 15k and 18k, and airspeed up to around Mach 0.5. Go faster than that, and/or higher than that, and pushing the throttles beyond max climb doesn't do anything.

tdracer thanks for more detail info.
Appreciate it.

[vilas]

or higher than that, and pushing the throttles beyond max climb doesn't do anything.

tdracer
Is it beyond CLB or beyond MCT because as you know when with OEI thrust levers are pushed to MCT.

[Jonty]

Here’s one then.
If CLB Thrust, MCT and TOGA are all the same, does the TOGA time limit still apply?

[Goldenrivett]

Originally Posted by Jonty

Here’s one then.
If CLB Thrust, MCT and TOGA are all the same, does the TOGA time limit still apply?

Yes. The limiting rpm may all be the same at Altitude, but EGT limits are different.
See FCOM, LIM-ENG: Thrust Setting/EGT limits.

[tdracer]

Originally Posted by vilas

tdracer
Is it beyond CLB or beyond MCT because as you know when with OEI thrust levers are pushed to MCT.

At least on all the engines I'm familiar with, MCT is never above max CLB. Usually, at somewhere around 30k, MCT becomes the same max CLB, below that MCT is a bit less. So out of the takeoff envelope, max climb is as good as it's going to get.

[Dave Therhino]

Originally Posted by tdracer

At least on all the engines I'm familiar with, MCT is never above max CLB. Usually, at somewhere around 30k, MCT becomes the same max CLB, below that MCT is a bit less. So out of the takeoff envelope, max climb is as good as it's going to get.

Not sure what you really meant to say there, but MCT is the maximum rated thrust outside of the conditions under which the time-limited takeoff thrust is available. Max climb can't be higher than the maximum rated thrust. Did you mean max clb at the end of your second sentence and in your third sentence? Am I missing something?

[tdracer]

Originally Posted by Dave Therhino

Not sure what you really meant to say there, but MCT is the maximum rated thrust outside of the conditions under which the time-limited takeoff thrust is available. Max climb can't be higher than the maximum rated thrust. Did you mean max clb at the end of your second sentence and in your third sentence? Am I missing something?

Whoops, yes I misspoke (misswrote?). Climb is not always higher than Con - I was thinking of something else.
However at altitude (usually above 30k), Max Con and Max Climb are typically the same thing.

[FlightDetent]

Thus, in response to vilas:

above 15-17k - the engine would typically not deliver more than MAX CON
above 30-ish k - the engine would typically not deliver more than MAX CLB

correct?