MCT at cruise
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737ngpilot
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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.
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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.
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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.
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.
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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.
Last edited by bubbers44; 27th Sep 2013 at 02:45.
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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?
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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.
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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.
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.
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i believe that as you climb there is a point at which MCT is not that much greater than CLB
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[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?
How can any prolonged setting be higher then Max Continuous?
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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)
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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'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)
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.
Last edited by de facto; 28th Sep 2013 at 08:27.
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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.
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.
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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.
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.
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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.
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.
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Code:
It should indeed be routine to select MCT during cruise (B737NG). Check the bulletins section of your volume 1.
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.
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.
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.
Last edited by de facto; 29th Sep 2013 at 09:49.
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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.
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.
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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."
From Jet Transport Performance Methods, Blake, et al 2009.
Thrust Ratings
So what is a thrust rating? Simply put, a thrust rating is a maximum level of engine thrust that is permitted for a specific phase of flight. For example, takeoff has its own specific thrust level, called Maximum Takeoff Thrust. That level of thrust can not be used at any other time during the flight. Also, as you’ll see, it can be used only for a specified number of minutes when taking off.
Normal climb to altitude has a different thrust level called Maximum Climb Thrust, or MClT. Similarly, cruise has its own rating, called Maximum Cruise Thrust, or MCrT.
For emergency purposes such as driftdown following an engine failure in cruise, there is a specific thrust rating called Maximum Continuous Thrust, or MCT.
A fifth rating exists, called Go-around Thrust, sometimes also referred to as Maximum Inflight Takeoff Thrust. This is a special rating used only at lower speeds and altitudes such as during a missed approach when maximum possible performance may be required.
So what is a thrust rating? Simply put, a thrust rating is a maximum level of engine thrust that is permitted for a specific phase of flight. For example, takeoff has its own specific thrust level, called Maximum Takeoff Thrust. That level of thrust can not be used at any other time during the flight. Also, as you’ll see, it can be used only for a specified number of minutes when taking off.
Normal climb to altitude has a different thrust level called Maximum Climb Thrust, or MClT. Similarly, cruise has its own rating, called Maximum Cruise Thrust, or MCrT.
For emergency purposes such as driftdown following an engine failure in cruise, there is a specific thrust rating called Maximum Continuous Thrust, or MCT.
A fifth rating exists, called Go-around Thrust, sometimes also referred to as Maximum Inflight Takeoff Thrust. This is a special rating used only at lower speeds and altitudes such as during a missed approach when maximum possible performance may be required.
The Five Thrust Ratings
At the beginning of the chapter, we said that there are five separate thrust ratings, each applicable to a particular phase of flight. Three of these are called certified thrust ratings, meaning that they are the basis of airplane performance
data which is governed by aviation regulations such as the United States Federal Aviation Regulations and thus are published in the Airplane Flight Manual (AFM) and have the force of law. Compliance with these certified thrust ratings is mandatory.
At the beginning of the chapter, we said that there are five separate thrust ratings, each applicable to a particular phase of flight. Three of these are called certified thrust ratings, meaning that they are the basis of airplane performance
data which is governed by aviation regulations such as the United States Federal Aviation Regulations and thus are published in the Airplane Flight Manual (AFM) and have the force of law. Compliance with these certified thrust ratings is mandatory.
maximum continuous thrust
This is the third of the “certified” thrust levels.
Maximum Continuous Thrust, or MCT, is a special thrust rating that is only usable in the event of some emergency situation. It may not be used in normal operation.2 MCT is the greatest amount of thrust that can be used in flight, with the exception of takeoff and landing.
This is the third of the “certified” thrust levels.
Maximum Continuous Thrust, or MCT, is a special thrust rating that is only usable in the event of some emergency situation. It may not be used in normal operation.2 MCT is the greatest amount of thrust that can be used in flight, with the exception of takeoff and landing.
2. For some engines, the maximum continuous thrust rating is the same as the maximum climb thrust rating; in those cases, this statement does not apply.
Last edited by ImbracableCrunk; 29th Sep 2013 at 14:00.