A320 MCT at cruise
 

Say you have a situation in cruise where you need to goose the power a bit more than the A/T is giving you. Does going into MCT make a difference? Is it advised? Pointless?

Conversely, hitting a wave and heading toward overseer, does moving the levers to IDLE make a difference?

I know it's a lot to ask, but could you give some indication as to what type aircraft you're referring to?

Done.

Inadvertent deletion.

Well I do it at high alt in cruise in the B737NG.
Remember, you just change your trust Limit. Might come in handy in turbulence or a turn.
Common sense, really.

Just push the thrust levers full forward; or "conversely", just pull them all the way back!

Are you a pilot, or is this another Flight Sim question?

Thanks for intruding,
I am talking about speed deviations at altitude. You can shove your thrust levers up and down by yourself if you wish yo do so of course. I prefer the A/T during hours of cruise.

If you are using MCT for anything other than getting out of an unforeseen low speed situation at hight alt OR an engine failure, then you need to have a good long think about what you are doing.

For those who think this is "common sense" read "complete stupidity". Common sense in not going up so high in turbulent conditions or if you need it for a turn?????

Please explain "having a long good think". About what? Cause it is not in your SOP? I am really interested where it could hurt you.

That's not good advice at high altitude. CFMs can take a very long time to get back to the required thrust from flight idle leading to airspeed loss and/or altitude loss and loss of separation.

If the engines have full climb thrust targeted, moving the lever to MCT or TOGA makes no difference at cruise altitude, where CLB, MCT and TOGA thrust limit are the same. (I haven't seen this written down, however I have tried it out).

If you are in overspeed with ATHR on, idle will be targeted anyway. Hence the QRH overspeed line: Thrust reduction....... Monitor. (If Athr on), so closing the thrust levers will achieve nothing.

For what it's worth, when I am flying the A320 (and especially the A321) in turbulence with large airspeed variation, I switch to speed mode from mach. The Autothrust pins the speed very well compared to the lack lustre performance in mach. On the A321 where the VLS to VMax is often tight, this can really help. Obvious caveat, watch your mach with changing temperature.

Boeing article recommends using speed brakes for speed control(overspeed condition/potential) instead of large power reduction. Quicker speed correction and avoids engine spool problems.

Front range of the Rocky Mountains, every winter we have mountain waves, and company procedure is to use speedbrakes and MCT to mitigate, MCT and Climb trust is the same at altitude.... Let me add I have seen airspeed change 50Knots in seconds, MCT/ Climb to power out is totally acceptable.

Not with me you aint ,unless you are in a stall or in an emergency descent..True,but MCT is there not only for engine failure...obviously if the speed drops and cruise N1 isnt sufficient,MCT is there for that.
Thats the way i do it.(unless during turns),and its in the FCTM,but hey seems like some here threw it away without reading it moons ago:E

The OP still refuses to give an airplane or engine type, or tell us whether this is a real or FlightSim question...

If the autothrottles are not keeping up with external influences, whether it be mountain wave, turbulence, wind shear, or something else, then the simple answer is to take over manually, regardless of what someone might "prefer". If the conditions are so extreme that the autothrottles command IDLE as he posited, then "loss of separation" is not likely an immediate factor. If you are pushing the red line AND climbing in a wave, spool-up time should also not be an immediate factor unless you got into a "coffin corner" situation in the first place, whether by bad planning or extreme bad luck.

I do agree with misd-agin that speedbrakes are preferable to excessive thrust reduction at high altitude. However, the question appeared to be regarding the ability to control the thrust. Anyone who "prefers" to use autothrottles to control thrust when a described extreme/limiting/edge-of-the-envelope situation exists is not someone I'd "prefer" to fly with.

It's in the title. This Spot. RIGHT HERE. A320. Up at the top. ^^^
 

A320. It's in the title.

737ngpilot: you look like a pilot who's been there, done that and knows what the question was.

To you intruder:
I am talking about daily ops, not extremes. And yes, in an airplane, not FS.
Stupid being at that level? You have not flown long range overwater yet, or over parts of the world, where two way comms are difficult or not available. Or maybe you choose by default Fl 280 for a long stretch?

Anyway, feel free to choose another flight if it happens me to be the skipper.

wave? overseer?

I'm a pilot. How about you? Your answer doesn't make sense.

The reason I ask is that at cruise, the donuts and the max EPR ticks are in line with each other. So does moving out of CLB really give you more thrust?

I say no.

Hey intruder, how about you take it down a notch.

I didn't refuse to clarify anything. I'm not on this board daily it may take me a few days to response to posts.

Calm down.

A320 (check the title)

And I don't know why the engine type has anything to do with it but we have IAE V2500s.

That's the question here - with the donuts and max EPR ticks touching, do you really get more thrust?

We had a situation in an MD80 on a short flight and my captain got a little slow at 36,500ft so called it out and he used alt hold and MCT to regain speed but it was too late. Using MCT actually lowered our N1 and we started to get buffeting so descended at 500 fpm to not stall. We were in the clouds and had opposite direction traffic at fl350 5 miles in front.

That is the only time in my career I Felt out of control as far as keeping our clearance. It never happened when I was captain even when my FO said we could cross a climb fix when transitioning to the 757. The 727was a slug so never accepted a clearance unless I knew We could do it.

ALT, A 737 flt LAS to sfo over the Sierra Nevadas we went from mct to idle with speed brakes to keep flying at fl350. We didn't exceed any limits and had no training. I think most pilots could figure it out too but can an Airbus autopilot do it? Speed brakes in cruise is not in their software is my guess.

To wrap it all up, the MCT is the A/T limit you select. Nothing else. Ever noticed that during approach, your limit goes to G/A? all a matter of understanding what you are doing. Or are some people again afraid from chief pilots, layers etc., cause it is not in their Vol 1, part 8?

i believe that as you climb there is a point at which MCT is not that much greater than CLB

All depends on selected T/O trust, and ambient conditions, altitude. You do not worry about this. But max continuous, is MAX continuous, it will not be lower then your Climb trust, and can be substantial higher to save the day.

When I was new on the 320 I regularly used MCT when
instructed to expedite climb - then all hell broke loose in
the flt dept when they found that me and my batch (all
ex Boeing) were doing it. We never ever got a definitive
reason as to why, in pilotage terms, we can't damn well
use it to expedite climb. But its their sand castle so we
just shutup and did what we were told.

Only once did I use MCT in cruise when I was dumb
and silly enough to leave the cockpit for an expended
urgent dunny visit with a 200hr wonder at the helm. We
were in an area of CBs but the hdg I set beforehand
was smooth and told Spanky not to change hdg or alt
unless we lost pressurisation or an engine. We were at
REC MAX - 300ft and about 1000ft over OPT due to
enroute ATC constraints further down the track which
would've duckshoved us to FL270 for the remaining 4
hours.

Cutting a long story short - just before I got back the
space cadet had changed hdg and steered us straight
into a bloody cell where the TAT went up by a large
10* and max CRZ power wasn't enough to keep the
speed from dropping off - so I went to MCT. Young
eager-beaver said he saw a break to get closer to track
but failed to scan beyond 10nm and took us smack in
to a blind alley.

I checked closely today while enroute. There is no difference between MCT and CLB.

[QUOTE]We had a situation in an MD80 on a short flight and my captain got a little slow at 36,500ft so called it out and he used alt hold and MCT to regain speed but it was too late. Using MCT actually lowered our N1 and we started to get buffeting so descended at 500 fpm.

How can any prolonged setting be higher then Max Continuous?

Up at FL350, Max CRZ, MCT and TOGA EPR are exactly the same.
Demo'ed many times in the sim (A320 IAE)
mcdhu

I'm 99% sure there was a Boeing bulletin issued which recommended selection of MCT in turbulent cruise conditions. I'm flying later today ill check it out and confirm. (737NG by the way)

Coffin corner?in a commercial aircraft?:hmm:
Please continue to do so.
It shouldnt be a routine...but if you have to do it then do it,no prob with that..
A proper fmc input (oat at t/c especially)will provide you with a correct max cruise.
I normally like to be 1000 ft below max when possible/forecast turbulence,when flying into a warmer mass...
If you dont push it too much use of mct should be rare..used it twice in a year in cruise obviously.

It should indeed be routine to select MCT during cruise (B737NG). Check the bulletins section of your volume 1.

And to Chuck Intruder, likewise it should never be routine to go idle in cruise, pr. same bulletin. Boeing go as far as to recommend to guard the auto throttle to prevent it from going below 60% N1.

I'll save you the time... These are the headlines. For the background, have a look in the manual for yourself:


Subject:
Reduced Engine Response Times

Reason:
This bulletin informs 737NG flight crews of slow engine acceleration following thrust reduction at cruise altitude due to a recent EEC software update. The bulletin provides suggested techniques to help prevent excessive airspeed loss.

Operating Instructions
Pilots may want to use the following techniques to avoid excessive speed loss due to slow engine acceleration:

1. Use the autopilot and autothrottle as much as possible.

2. When established at cruise altitude, manually select either CLB or CONT on the FMC N1 Limit page. This will ensure maximum available thrust.

3. If the airplane experiences a sudden increase in airspeed that causes the autothrottle to reduce thrust, manually guard the thrust levers to maintain a minimum of 60% N1, if possible. If thrust is reduced below 60% N1, a significantly longer time will be required for the engines to spool up if the time at idle thrust is less than 60 seconds.

4. If the airplane experiences a sudden increase in airspeed, consider using smooth extension of the speed brakes to increase drag and to avoid large thrust reductions.

5. No specific crew actions are needed if the thrust remains at idle for longer than 60 seconds or if the descent is to an altitude below FL300. Normal engine acceleration can be expected in these cases.

Item 2 (post #34) probably means that CLB is equal to CONT for the B737NG at cruise altitude.

That may not apply for different airplanes, different engines, different altitudes, but generally, for high-bypass-ratio jet engines, CLB will be close to max. continuous above a certain altitude.

At cruise, on the B738, they're all the same except CRZ, which is maybe 5% less.

Kramer,

What does it mean 'may want to use the following techniques to avoid...'


Would you suggest that slow engine acceleration (understand it as loss of speed and AT correction is not acceptable due to your low speed margin) is an every day problem?are you flying every day at such an altitude that requires you to use this TECHNIQUE?
In cruise,the thrust setting should be CRZ unless you need MCT until you either decide to descend or if acceptable to wait for the turbulence to reduce..

Routine is what it is ...Standard thrust setting for cruise is CRZ.
Non routine technique described in your post.

DeFacto:

You deleted the SOP part of your last message.

Probably as you looked it up and could not find it.
I have to see the first SOP where it is mentioned to verify Cruise limit on A/T in cruise. And a have seen a few.

A few posts back you talked about "use of MCT". I am not talking about use of MCT, but Selecting MCT as a trust limit. That is different.

I know this started as an Airbus thread, but this is an interesting discussion for Boeing folks, too.

From Jet Transport Performance Methods, Blake, et al 2009.

In the 737NG, MCT is the same as CLB. Following note 2, it may be used in "normal operation."

ImbracableCrunk, I thank you for that.
Some pilots can hardly do anything, unless it is written in stone.