Use of MCT on A320 family during CLIMB

[CMpilot1]

Hi Guys,
Is it a recommended practice to use MCT during climb under normal operations ? If you take the case of A321, you will find it's very sluggish to climb when it's fully loaded. I have seen Captains using MCT to overcome this. In my opinion, this procedure should be resorted to only under abnormal operations. Eg; single engine scenario. Any thoughts?

[tom775257]

It just the captains showing lack of knowledge of the aircraft. In the FL200s or so and above where climb actually becomes sluggish, MCT and climb are the same thrust setting anyway.

[FlyingStone]

This is what Airbus says:

It [Maximum Continuous Thrust] is the maximum thrust certified for continuous use. This rating should be used, at the pilot’s
discretion, only when required to ensure safe flight (engine failure).

If you take the case of A321, you will find it's very sluggish to climb when it's fully loaded. I have seen Captains using MCT to overcome this.

Sluggish as in what? Low rate of climb? Fully loaded commercial aircraft doesn't have the performance of an F-18 and most of the times you just have to accept it. Tell the ATC "unable" and drink your coffee...

[CMpilot1]

Sluggish as compared to A320

[vilas]

Airlines should clarify this in their SOPs so that pilots don't make their own procedures.

[Amadis of Gaul]

We don't have a limitation on MCT use, but the only place I've had to resort to it is SJO when taking off on Rwy 07 in a heavy 321 on a hot day in order to make that first fix above 5,000'.

[PENKO]

Flying stone, do you have a reference for those Airbus quotes?

[vilas]

We don't have a limitation on MCT use, but the only place I've had to resort to it is SJO when taking off on Rwy 07 in a heavy 321 on a hot day in order to make that first fix above 5,000'.
If you have to use MCT then don't you think there is a problem with your RTOW charts?

[CaptainMongo]

Interesting thread.

We are directed by non normal procedure when we must use MCT. MCT use at other times is not addressed. By definition an engine can operated at MCT for an unlimited period of time. I use MCT only when necessary to increase the climb rate for turbulence or ATC request when a reduced climb speed is not appropriate or has already been selected. Selecting thrust up to MCT may also be necessary when a "SPEED SPEED SPEED" warning is present.

As Tom also said if I see a pilot selecting MCT in the mid to high 20's we talk about it at cruise.

[Amadis of Gaul]

If you have to use MCT then don't you think there is a problem with your RTOW charts?

Not necessarily. I'm just not a fan of making things by the very skin of my teeth.

[tubby linton]

Sometimes see something similar in BCN. One of the options could be a TOGA take off and a higher acceleration altitude,

[vilas]

A long time ago when A310 was new during a route check an Airbus TRE mentioned to me that engine warranty is not valid if MCT is used when operating with two engines. But cannot find anything in documents.

[FlightDetent]

tubby: quite off the topic, but I seem to remember BCN brief saying "if unable to meet RNAV SID altitude constraints, NADP1 shall be used".

[FlyingStone]

Flying stone, do you have a reference for those Airbus quotes?

FCOM PER-THR-MCT

[Jonty]

I used MCT today, and seemed to have survived the experience!

It must be a miracle!

[Metro man]

You may get a call from the office for using MCT if they flag it in the flight data monitoring. It's surprising what it picks up, supposedly it's anonymous and used to identify trends so the training department can correct them but it can be unlocked and individuals identified if required.

At a recent fleet meeting the DFO observed that our aircraft spent a lot of time in selected speed and hoped that this was due to ATC instructions.

[FlightDetent]

Oh dear. Get him a girlfriend!

[stilton]

Used MCT on the 757 a few times over the years, never with an engine failure.

On transatlantic flights westbound at the limit of the aircraft's performance we used
a full power take off followed by an MCT climb to 'washout altitude' where it was the
same as climb thrust.

This gave us a quicker climb to cruise altitude and always put us ahead of flight plan fuel.

Never had to stop.

[Amadis of Gaul]

You may get a call from the office for using MCT if they flag it in the flight data monitoring.

I doubt it.

[Zaphod Beblebrox]

While not a specifically approved practice, at our company some may use the MCT detent after takeoff from LAS or RNO or other high altitude or terrain constrained airport on a hot day until the flaps are up and the aircraft is on profile at climb speed.

The FMA is flashing climb but in a 321 the climb rate is so sluggish and the departures are often towards mountains. This is particularly used at night.

The climb power schedule is a customer selected condition. Customers can select the most economical climb schedule as far as engine life and that is the lowest power setting that still gets the job done.

MCT is an FAR part 1 defined limit: 8. Rated Maximum Continuous Power or Thrust (unaugmented) - § 33.7(c)(1)(ii).
a. For each type certificated engine, the applicant must determine the value for the rated maximum continuous power or thrust. The applicant must demonstrate by engine test that the rated maximum continuous power or thrust is achieved without exceeding the operating limitations established in compliance with part 33 and required in § 33.7(c). The ambient conditions for which the engine must produce the rated maximum continuous power or thrust are specified in § 1.1

Airbus Climb schedules could be as high as MCT or considerably lower, as my company's is.

[Old Fella]

By definition there should be no time limit on the use of MCT. Do any of you folk think the engine manufacturer is going to publish a Max Continuous Thrust Limit which is time limited? Or am I just expressing the practical opinion of an old Flight Engineer?

[applecrumble]

I've often thought about the fact that technically speaking there is absolutely no limit on the amount of time MCT can be used (by definition).
But above about FL200 it's the same as TOGA.
You are limited to 5 mins with TOGA (two engines). So if you just move it that one notch further....... no change in thrust but technically now time limited. 😬

[Old Fella]

I guess terminology can sometimes be confusing and I appreciate that there is no longer aeroplanes being built which carry Flight Engineers. As one of those dinosaurs of the past, to my mind, even considering TOGA in the example cited i.e., at Flight Levels above FL200, makes no sense. My understanding of TOGA is that it is a thrust setting which may be used for Take Off and/or Go Around for a limited time. That the MCT and TOGA thrust available are one and the same above FL200 is not a surprise to me. Common sense would dictate that TOGA Thrust Lever position at those levels is simply another position which if selected makes no difference to thrust produced and therefore, if selected for some obscure reason, MCT limits would apply.

[Right Way Up]

But above about FL200 it's the same as TOGA.
You are limited to 5 mins with TOGA (two engines). So if you just move it that one notch further....... no change in thrust but technically now time limited. 😬

But following that logic as TOGA is the same as CLB thrust at high levels we would be restricted using CLB thrust!

[applecrumble]

Love being devils advocate! You're correct if we take it at face value but as old fella quite rightly says, they are really referring to low altitude.

Some very experienced pilots haven't necessarily considered this fact as they seem perplexed for a short while when you tell them.

AF447 - The thrust levers were put into TOGA detent numerous times.
I can't help thinking that they expected a large thrust response. If you think about it, we only see TOGA at low altitude for go around (same in the simulator). We've been conditioned into expecting a large thrust response..... but if your above 200 you aren't going to get it!

[vilas]

From FCOM as quoted before:

It is the maximum thrust certified for continuous use. This rating should be used, at the pilot’s discretion, only when required to ensure safe flight (engine failure).


It is unambiguous. Only thing that comes to my mind is, they can't be serious. Nobody seems to care about it neither pilots nor the airlines. What is the compulsion that makes them insert this?

[A320ECAM]

Guys, be careful when using MCT during normal operations.

I knew a captain in my company who used to sometimes use TOGA thrust during takeoff for the sake of it. Then one day when LVR CLB flashed, he pulled it back one detent (instead of two) and didn't realise. MCT on climbout and ended up busting the speed constraint. He got called into the office and was chewed out.

[Cough]

Any engineer like to comment on the engine wear aspects of long term MCT use during climb?

[Amadis of Gaul]

Sounds like he wasn't watching his speed.

[Airmann]

I would approach this question from another angle.

If you perform a takeoff at low weights what N1 do you get when you select CLB versus doing a takeoff at higher weights assuming all other conditions remain the same?

I've been off the 320 for a while now but if my memory serves me correct the CLB thrust is different depending on the weight? Am i right in saying this?

On the widebody airbuses you can select a derated climb. However, without moving the thrust levers you can always switch to maximum climb thrust using the FMS, and this will give you an N1, in some cases, around 25% higher than the derated case. It's great when ATC asks you to expedite.

So on the narrow-body busses with no option to select a derated climb am i right in assuming the aircraft is always choosing a derated climb given the weights? Or is it always targeting maximum climb thrust. I'm sure that at various weights we had different climb thrusts?

Now coming back to the derated climb Vs normal climb thrust on the wide bodies. I'm not sure if the Max CLB thrust is the same as MCT but it must be darn close because it is pretty high. So I'm wondering why we get that option in the big busses but on the narrow bodies we are left with either the calculated CLB thrust or MCT.

And looking at my 320 FCOM it says specifically that MCT is to be used at pilots discretion but in parenthesis says 'single engine'. Which is seriously confusing because you wonder if that is an example case or a restriction.

[Metro man]

FLEX is the norm rather than a fixed derate.

[Old Fella]

Getting back to the original question. CMpilot1 is of the opinion that MCT should be used only in abnormal operations. Putting aside all the various options mentioned to date I repeat my question. Does anyone think the engine manufacturer is going publish a Maximum CONTINUOUS Thrust which they believe will be detrimental to the engine? I think not. Different operators have different approaches as to how they wish their aircraft to be operated. If the engine manufacturer says the MCT is X, then you should expect that thrust setting may be used unlimited (for as long as desired/required). COUGH asks about engine wear in relation to the use of MCT. In many cases MCT and CLMB will be the same. Where MCT is higher than CLMB, and CLMB is used the time to climb will be greater than that if MCT were used. Engines remember RPM, Time and EGT and where MCT is higher than CLMB there will likely be some reduction in the service life of the engine. How significant this is is dependent on how much higher the RPM and EGT are for MCT v CLMB. If any particular operator wishes to impose a limit on MCT use they should explain the reasons why.

[Romasik]

Come on! It's quite simple. CLB1 and CLB2 are there mostly to reduce engine wear. With MCT you will not bust limitations but more significantly reduce engine life if use it frequently. So, go ahead, if you really need it, but don't make it a habit. Once you start using it with no safety reason there will be nothing to limit your desire to get the aicraft to it's cruising level faster and call for coffee:)

[vilas]

There is a definitely a catch. The FCOM has clearly stated and the onus is on the user. The sluggish climb and clearing by skin of teeth is all subjective as people have even vehemently opposed the use of TOGA in EFATO scenario where very accurate flying is required to achieve the certification performance. Quoted below from an old thread:

barit1 8th Oct 2008, 22:57
From an old engineman's perspective -

Max CLB is a OEM warranty rating, and NOT a certification point. At some conditions, notably TOC, CLB and MCT may in fact converge.

But MCT is not a safety issue at all; It's a matter of warranty coverage by the OEM. If your FDR shows untoward MCT usage, your airline may have trouble collecting on parts life warranty.

For years, I did repeated ground testing of big fans in which we accelerated slowly to MCT, held 5 minutes for thermal stabilization, then ran 30 min. or more at various TO ratings before retarding below MCT. I can show you over 100 hrs. experience doing this testing on one engine. There was never a mechanical reliability issue, although some performance falloff naturally occurred.

So it's strictly the Captain's choice; you trade off increased deterioration (which means more fuel burned over the on-wing engine life) vs making a FL "gate". Talk it over with your bean counters, make the decision that's right for your airline, but don't let safety worry you.

[jaja]

FCOM PER-THR-MCT is crystal clear :

DEFINITION
Applicable to: ALL
It is the maximum thrust certified for continuous use. This rating should be used, at the pilot’s discretion, only when required to ensure safe flight (engine failure).

so only use MCT at engine failure !

[Amadis of Gaul]

If that's a typical Frenglish translation, it could be that the intent was to say "e.g. engine failure" rather than engine failure only.

[Romasik]

Don't take all Airbus words at face value. There are numerous examples when their writing is ambiguous. Look at your own phrase. It says "at the pilot's discretion". MCT is not a discretion when engine fails. It's an established procedure. (Engine failure) in brackets looks like an example, not a single case of MCT usage. Otherwise it should have been written "to ensure safe flight in case of an engine failure". Everybody reads what he wants to read. The same words.

[vilas]

Boeing also says MCT is for use only in emergency.
Now what constitutes an emergency surely not ATC requirements or boredom with existing climb rate. That's why without SOP guidelines/company policy (if you like) the argument will never end.

[CaptainMongo]

Sounds like he wasn't watching his speed.

Or his FMA's

[vilas]

With AEO if thrust levers are brought to MCT LVR CLB will keep flashing. It's gross negligence.

[stilton]

Not seen that in any Boeing manual Vilas, do you have a reference ?

[vilas]

Any engine/aircraft manufacturer would define MCT as that.
Jet engine basics by Boeing on P2 page 20
This is special thrust rating, sometimes referred to as MCT or CON. It is intended to only be used only in emergency, but has no limitation.

Boeing jet transport performance methods states following:

For emergency purposes such as driftdown following an engine failure in cruise, there is a specific thrust rating called Maximum Continuous Thrust, or MCT

[Jonty]

I have to say I find this quite amusing.

MCT is the maximum thrust certified for continuous use. There is not certification problem with its use, there is however a ware issue, as there is with all engine use.

Airbus has its advice spot on in my opinion. Use it only for safe flight. If it's not required for safe flight, then why are you using it? However, "safe flight" is open to interpretation. Would safe flight mean meeting an ATC restriction? How about if not meeting that ATC restriction would take you outside controlled airspace?

So my advice is to use it if you feel you need it, but use it sparingly. It has a cost, but doesn't everything!

[Old Fella]

Any engine/aircraft manufacturer would define MCT as that.
Jet engine basics by Boeing on P2 page 20


Boeing jet transport performance methods states following:




From Pratt & Whitney publication "The Aircraft Gas Turbine Engine and its operation" P/No P&W 182408.

"Maximum Continuous". This rating is the maximum thrust certified for continuous use. For the purpose of P & W service policy coverage and prolonging engine life this rating should be used, at the pilot's discretion, only when required to ensure safe flight. NOTHING ABOUT BEING RESTRICTED TO EMERGENCY SITUATIONS.

"Maximum Climb" Maximum Climb thrust is the maximum thrust approved for NORMAL climb. On some engines, Maximum Continuous and Maximum Climb thrust ARE THE SAME.

Obviously engine life will be enhanced by using the least amount of thrust required to achieve the performance required to safely operate the aircraft. As I have previously stated the parameters which impact most on engine life are
RPM and EGT. The amount of time these parameters are at a certain value determines what effect they have on the life of the engine. Most operators will stipulate permissable de-rates for take-off thrust and reduced thrust climbs, to extend overall engine life, ACCEPTING THE ADDITIONAL FUEL BURN INHERENT IN REDUCED CLIMB THRUST SETTINGS WITH THE CONSEQUENT LONGER TIME TO CLIMB.

[vilas]

For the purpose of PW service policy coverage and prolonging engine life this rating should be used, at the pilot's discretion, only when required to ensure safe flight. NOTHING ABOUT BEING RESTRICTED TO EMERGENCY SITUATION
Now this is a literary debate.If you cannot ensure safe flight without the use of MCT it could be termed emergency/abnormal. Your own quote if turned around means engine life is prolonged if you avoid use of MCT.Service policy coverage means you loose some maintenance credits if you indulge in MCT. It's evident that pilots use MCT with individual justifications. They will continue to do so unless their company tells them not to. So I think enough evidence is produced about what engine/ aircraft manufacturer says or wants. Time to move on.

[stilton]

No, nothing in my flight manual restricting MCT to emergencies.


And if it's 'intended for emergencies but has no limitation' then it has no limitation.

[Uplinker]

But using MCT for 'standard' climbs will cause more engine wear and shorter on-wing life. Companys might be unwittingly spending a lot more £ thousands on engine changes and rebuilds than if MCT were not used.

On the A330, we used 2 derated climb power settings which were something like 8% and 13% less than CLB power to reduce engine wear.

[Old Fella]

I don't think anyone, by now, really believes that using MCT as a matter of course will not reduce engine life. Too many however seem to think there is a time limit on the use of MCT. Engine manufacturers certify an engine to operate within certain parameters. They have ascertained that MCT does not cause "damage" to the engine and therefore do not impose any time constraint on its use. However, they do acknowledge that it is preferable to use lesser thrust settings, where MCT is not required to sustain safe flight, to extend engine life beyond what they believe to be the reasonable design life of the engine. Don't really think there is much more to said on this matter.

[FlyingStone]

So, after 3 pages of discussion on the legality and technicality of the use of MCT in two engine operation, there is something left to be discussed.

WHY would one need to use the MCT on the regular basis in normal operations anyway?

[Romasik]

WHY would one need to use the MCT on the regular basis in normal operations anyway?
To climb faster or steeper for whatever reason.

[Old Fella]

So, after 3 pages of discussion on the legality and technicality of the use of MCT in two engine operation, there is something left to be discussed.

WHY would one need to use the MCT on the regular basis in normal operations anyway?

Until the "bean counters" started making the rules and automation of just about everything to do with flying an aircraft along with with the introduction of all these variables such as De-rates, Flex Thrust, Climb 1 and Climb 2 etc etc pilots either set, or called for, the power setting they wanted. They also knew a lot about the aircraft as a whole and with few exceptions operated the aircraft as if they owned it, thus treating it with care. Most could quote operating limits off the top of their head. It seems these days everything is so automated that the knowledge of how and why things work is not as deep as it once was. It is called progress I know. Just not convinced, yet.

[Uplinker]

The bean counters also pay our wages, and they need money to do that......

[Denti]

To climb faster or steeper for whatever reason.

That is what the word "unable" is made for, isn't it? There seems to be a very large fear in many pilots to use that one.

[Cough]

Obviously relevant to my operator only - (When I was on it!) We had a note from the Tech team saying we were not to use MCT in normal ops. The background is related to engine wear and contracts (hence previous comment)

Have to say, in 7 years flying I never needed MCT. I, like Denti used unable or asked kindly for a different routing if required.

[CMpilot1]

Thanks to all my fellow sky buddies for their valuable inputs. I have found out that the captain was not really aware of what the book had to say. Usually, he doesn't deviate from the book. I guess, in this case, he overlooked that single para under PER-THR-MCT chapter.

[FlightDetent]

Concurring with the above, the AFM has no limitation on MCT thrust, FCOM does. So the applicability of the restriction is clear.

[Amadis of Gaul]

I have found out that the captain was not really aware of what the book had to say.



More common than it should be, isn't it?

[LEM]

Too many wannabees Artists out there...

Using MCT is NOT the way to cope with restrictions or boredom.

Use only in case it would be unsafe not to use it. Engine failure, of course.
Other reasons like sudden need to climb over CB, but you will have to explain...

Routinely using it as a trick for some sort of benefit is unthinkable and unacceptable!

[Amadis of Gaul]

Routinely using it as a trick for some sort of benefit is unthinkable and unacceptable!




Such drama...I don't think it's nearly as unthinkable or unacceptable as decaf coffee, and yet the latter does exist.

[vilas]

Other reasons like sudden need to climb over CB, but you will have to explain... It never helps going suddenly over the CB. MCT at altitude is not that much extra thrust.