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convair880mfan
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Can all jetliners take off at a climb thrust setting if they are lightly loaded?

Tue Aug 31, 2021 5:39 pm

I've noticed that some jetliners take off and do not reduce thrust after takeoff for the initial climb. Some seem to actually add thrust beyond the takeoff thrust settings. Maybe I am wrong about this but if it is true, can all jetliners do this or only certain types? I think the Boeing 757 and the MD-90 are aircraft that I have flown on where thrust was not reduced after takeoff for the initial climb. Any information would be appreciated. Thanks in advance for information or corrections for any mistakes I may have made.
 
Woodreau
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Re: Can all jetliners take off at a climb thrust setting if they are lightly loaded?

Tue Aug 31, 2021 7:41 pm

Sometimes the climb thrust setting is the same as the takeoff thrust setting. When you pull the thrust levers from the FLEX detent back to the CLB detent, nothing changes. The engines stay at the same thrust setting.
 
convair880mfan
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Re: Can all jetliners take off at a climb thrust setting if they are lightly loaded?

Tue Aug 31, 2021 8:31 pm

Thanks so much for your response, Woodreau. That would explain what I experienced. I wonder if all jetliners are capable of this? I guess given an unlimited runway length it would be possible. Do you think that really heavy aircraft can go from FLEX detent to CLB detent with the engines remaining at the same thrust setting? The Boeing 747? The Airbus A380?

Perhaps a pilot of an empty heavy jetliner like the 747,DC-10,A300 or MD11 could answer this. Not sure they ever fly without any payload except perhaps on a ferry flight.
 
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AirKevin
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Re: Can all jetliners take off at a climb thrust setting if they are lightly loaded?

Tue Aug 31, 2021 9:26 pm

Just to throw this out there, the Boeing jets and McDonnell-Douglas jets don't use detents on their thrust levers.
 
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Starlionblue
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Re: Can all jetliners take off at a climb thrust setting if they are lightly loaded?

Tue Aug 31, 2021 11:08 pm

convair880mfan wrote:
Thanks so much for your response, Woodreau. That would explain what I experienced. I wonder if all jetliners are capable of this? I guess given an unlimited runway length it would be possible. Do you think that really heavy aircraft can go from FLEX detent to CLB detent with the engines remaining at the same thrust setting? The Boeing 747? The Airbus A380?

Perhaps a pilot of an empty heavy jetliner like the 747,DC-10,A300 or MD11 could answer this. Not sure they ever fly without any payload except perhaps on a ferry flight.


Whether the thrust levels at takeoff and climb are similar isn't really about what a jetliner is "capable of". They depend on atmospheric conditions, runway length and condition, obstacles, and weight.

As AirKevin notes, Airbus uses TOGA, FLEX and CLB detents. Other airliners use other nomenclatures and thrust lever designs. However, the concepts of takeoff and climb thrust, as well as the associated reduced thrust settings, are the same.
 
AABusDrvr
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Re: Can all jetliners take off at a climb thrust setting if they are lightly loaded?

Wed Sep 01, 2021 1:32 am

On the 737, quite often climb thrust will actually be an increase in thrust, from whatever derated takeoff setting we use. In mountainous terrain, I will always select max climb thrust, even if we are planned for a derated CLB-1 or -2, This gets us clear of the terrain in less time, and will usually result in a thrust increase from takeoff thrust. We will also do this if heavy, or it's really hot out, and there are "at or above" altitude restrictions on the departure.
 
e38
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Re: Can all jetliners take off at a climb thrust setting if they are lightly loaded?

Wed Sep 01, 2021 1:42 am

convair880mfan wrote:
Some seem to actually add thrust beyond the takeoff thrust settings


convair880mfan, on the Airbus A320 series, takeoffs are accomplished with the thrust levers in the TOGA detent for a full thrust takeoff or in the FLX MCT detent for a reduced thrust, "flex," takeoff. If a pilot inadvertently selects the CL (climb) detent for takeoff thrust, a warning will annunciate at approximately 72 KIAS alerting the pilot to the improper selection of thrust; in other words, it is incorrect procedure to select CL for takeoff and the aircraft will let you know.

At thrust reduction altitude--normally around 1,000 feet above field elevation in the United States, although it can vary depending on location, terrain, local, and company procedures--the thrust levers are retarded from either TOGA or FLX MCT to the CL detent.

As Woodreau stated in Reply # 2 above, "Sometimes the climb thrust setting is the same as the takeoff thrust setting. When you pull the thrust levers from the FLEX detent back to the CLB detent nothing changes. The engines stay at the same thrust setting."

I agree with this statement and have also experienced it; however, convair880mfan, I have not had a situation where thrust increased when selecting CLB from either TOGA or FLX MCT, and in other aircraft I have flown where thrust was manually controlled, I don't ever remember a situation where it was required to add thrust when transitioning from the takeoff phase to the climb phase.

e38
 
bigb
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Re: Can all jetliners take off at a climb thrust setting if they are lightly loaded?

Wed Sep 01, 2021 12:12 pm

Takeoff thrust takes account Atmospheric conditions, weight, and runway conditions. There are situations where there will be a thrust reduction to CLB thrust once reaching thrust reduction altitude. There are some situations takeoff thrust is the same as CLB thrust and there are situations where takeoff thrust is less than CLB thrust (I’ve seen this with lightly load or empty 74s taking off from a long runway, cool day at sea level).
 
vikkyvik
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Re: Can all jetliners take off at a climb thrust setting if they are lightly loaded?

Wed Sep 01, 2021 2:12 pm

convair880mfan wrote:
I wonder if all jetliners are capable of this?


For commercial airliners, I think the answer is very likely "yes", given a long enough runway for the conditions.

You may not meet regulations in terms of runway length required and such, though.
 
FlapOperator
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Re: Can all jetliners take off at a climb thrust setting if they are lightly loaded?

Wed Sep 01, 2021 5:57 pm

AirKevin wrote:
Just to throw this out there, the Boeing jets and McDonnell-Douglas jets don't use detents on their thrust levers.


The MD-11 will set a Flex thrust via the FMCs to the autothrottles.

Usually the detents are flexible in their actual output, versus some kind of preset value.
 
FlapOperator
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Re: Can all jetliners take off at a climb thrust setting if they are lightly loaded?

Wed Sep 01, 2021 5:58 pm

vikkyvik wrote:
convair880mfan wrote:
I wonder if all jetliners are capable of this?


For commercial airliners, I think the answer is very likely "yes", given a long enough runway for the conditions.

You may not meet regulations in terms of runway length required and such, though.


Honestly, I bet your limitation would end up being tire speed.
 
vikkyvik
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Re: Can all jetliners take off at a climb thrust setting if they are lightly loaded?

Wed Sep 01, 2021 10:15 pm

FlapOperator wrote:
Honestly, I bet your limitation would end up being tire speed.


Why? I wouldn't think you'd need a significantly higher speed to lift off at marginally reduced thrust.
 
a320fan
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Re: Can all jetliners take off at a climb thrust setting if they are lightly loaded?

Thu Sep 02, 2021 8:31 am

e38 wrote:
I agree with this statement and have also experienced it; however, convair880mfan, I have not had a situation where thrust increased when selecting CLB from either TOGA or FLX MCT, and in other aircraft I have flown where thrust was manually controlled, I don't ever remember a situation where it was required to add thrust when transitioning from the takeoff phase to the climb phase.

e38


Not uncommon on Boeing aircraft. For example, I believe EK have an SOP to use full climb thrust in the 777 when above max landing weight. Unless you’re really heavy or going off a limiting runway, in a lot of cases this will mean the climb thrust setting is actually above the assumed temperature dératé used for takeoff.
 
r6russian
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Re: Can all jetliners take off at a climb thrust setting if they are lightly loaded?

Thu Sep 02, 2021 10:28 am

I was on 4 737NG flights in the last year, and every one, climb thrust was higher than takeoff thrust. All 4 flights took off from close to sea level airports at moderate to warm temps (DTW, MDW, RSW and BWI, all no hotter than 90F) so no concern for pressure altitude or temp adjustments

I was surprized taking off from Midway when they throttled up to climb thrust after taking off 22L at MDW in a full 738. I fugured, theres no way a full 738 on a 3hr flight can take off from a short runway like that with less than 26k thrust (i know 27k bump is only for SNA here in the states) but we rotated right around the intersection of the runways and were off the ground and climbing like a homesick angel. And then we throttled up for climb thrust. I was expecting a throttle down, but no, climb thrust was higher than takeoff thrust even being a full plane on a short runway. Cant expect everything my PMDG 737 does in FSX to repeat in real life
 
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Starlionblue
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Re: Can all jetliners take off at a climb thrust setting if they are lightly loaded?

Thu Sep 02, 2021 10:34 am

r6russian wrote:
I was on 4 737NG flights in the last year, and every one, climb thrust was higher than takeoff thrust. All 4 flights took off from close to sea level airports at moderate to warm temps (DTW, MDW, RSW and BWI, all no hotter than 90F) so no concern for pressure altitude or temp adjustments

I was surprized taking off from Midway when they throttled up to climb thrust after taking off 22L at MDW in a full 738. I fugured, theres no way a full 738 on a 3hr flight can take off from a short runway like that with less than 26k thrust (i know 27k bump is only for SNA here in the states) but we rotated right around the intersection of the runways and were off the ground and climbing like a homesick angel. And then we throttled up for climb thrust. I was expecting a throttle down, but no, climb thrust was higher than takeoff thrust even being a full plane on a short runway. Cant expect everything my PMDG 737 does in FSX to repeat in real life


We have to be able to continue the takeoff from that same runway on one engine without increasing thrust. Plenty of thrust available with two engines.
 
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Aaron747
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Re: Can all jetliners take off at a climb thrust setting if they are lightly loaded?

Thu Sep 02, 2021 2:15 pm

r6russian wrote:
I was on 4 737NG flights in the last year, and every one, climb thrust was higher than takeoff thrust. All 4 flights took off from close to sea level airports at moderate to warm temps (DTW, MDW, RSW and BWI, all no hotter than 90F) so no concern for pressure altitude or temp adjustments

I was surprized taking off from Midway when they throttled up to climb thrust after taking off 22L at MDW in a full 738. I fugured, theres no way a full 738 on a 3hr flight can take off from a short runway like that with less than 26k thrust (i know 27k bump is only for SNA here in the states) but we rotated right around the intersection of the runways and were off the ground and climbing like a homesick angel. And then we throttled up for climb thrust. I was expecting a throttle down, but no, climb thrust was higher than takeoff thrust even being a full plane on a short runway. Cant expect everything my PMDG 737 does in FSX to repeat in real life


Unbeknownst to you at the time, there may have also been a 15-20 knot wind right down the runway.
 
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AirKevin
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Re: Can all jetliners take off at a climb thrust setting if they are lightly loaded?

Sat Sep 04, 2021 12:06 am

FlapOperator wrote:
AirKevin wrote:
Just to throw this out there, the Boeing jets and McDonnell-Douglas jets don't use detents on their thrust levers.

The MD-11 will set a Flex thrust via the FMCs to the autothrottles.

Usually the detents are flexible in their actual output, versus some kind of preset value.

I think we're not talking about the same thing. The Airbus appears to have physical detents on the thrust levers, and it doesn't appear to be the case on the MD-11, as seen here.

 
BoeingGuy
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Re: Can all jetliners take off at a climb thrust setting if they are lightly loaded?

Sat Sep 04, 2021 11:09 pm

a320fan wrote:
e38 wrote:
I agree with this statement and have also experienced it; however, convair880mfan, I have not had a situation where thrust increased when selecting CLB from either TOGA or FLX MCT, and in other aircraft I have flown where thrust was manually controlled, I don't ever remember a situation where it was required to add thrust when transitioning from the takeoff phase to the climb phase.

e38


Not uncommon on Boeing aircraft. For example, I believe EK have an SOP to use full climb thrust in the 777 when above max landing weight. Unless you’re really heavy or going off a limiting runway, in a lot of cases this will mean the climb thrust setting is actually above the assumed temperature dératé used for takeoff.


Emirates has an option on the 777 that allows up to a 40% Assumed Temperature Thrust Reduction on the 777. IIRC, NZ has it also. That’s a lot of reduction. That is likely below the three climb thrust settings. A maximum of a 25% reduction is standard.

FYI, an Assumed Temperature Reduction is not properly called a “Derate”, although many including myself tend to use that term loosely. Fixed Derates are “Derates”. Assumed Temp is a “thrust reduction.”
 
FlapOperator
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Re: Can all jetliners take off at a climb thrust setting if they are lightly loaded?

Wed Sep 08, 2021 3:05 am

AirKevin wrote:
FlapOperator wrote:
AirKevin wrote:
Just to throw this out there, the Boeing jets and McDonnell-Douglas jets don't use detents on their thrust levers.

The MD-11 will set a Flex thrust via the FMCs to the autothrottles.

Usually the detents are flexible in their actual output, versus some kind of preset value.

I think we're not talking about the same thing. The Airbus appears to have physical detents on the thrust levers, and it doesn't appear to be the case on the MD-11, as seen here.



On the MD-11, to set your flex thrust for takeoff, you set that into the FMC. During takeoff, you can hit the auto-throttles, which will then use that data to clutch the actual handles into the correct thrust setting.

As you note, the 320 family has a number of detents, but those numbers are temperature influenced as well, with flex power being a derivative of a nominal max temperature.

In both cases, shoving the thrust levers/throttles all the way forward will give you max blast.
 
bluecrew
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Re: Can all jetliners take off at a climb thrust setting if they are lightly loaded?

Wed Sep 08, 2021 7:15 am

BoeingGuy wrote:
a320fan wrote:
e38 wrote:
I agree with this statement and have also experienced it; however, convair880mfan, I have not had a situation where thrust increased when selecting CLB from either TOGA or FLX MCT, and in other aircraft I have flown where thrust was manually controlled, I don't ever remember a situation where it was required to add thrust when transitioning from the takeoff phase to the climb phase.

e38


Not uncommon on Boeing aircraft. For example, I believe EK have an SOP to use full climb thrust in the 777 when above max landing weight. Unless you’re really heavy or going off a limiting runway, in a lot of cases this will mean the climb thrust setting is actually above the assumed temperature dératé used for takeoff.


Emirates has an option on the 777 that allows up to a 40% Assumed Temperature Thrust Reduction on the 777. IIRC, NZ has it also. That’s a lot of reduction. That is likely below the three climb thrust settings. A maximum of a 25% reduction is standard.

FYI, an Assumed Temperature Reduction is not properly called a “Derate”, although many including myself tend to use that term loosely. Fixed Derates are “Derates”. Assumed Temp is a “thrust reduction.”

I can't even imagine that... that's a huuuuge reduction in thrust.
Double Derate in the 737 is already pretty performance limited and that's a loss of 18% or so in klbs.

The E190 likes standard TO-2 on longer runways, TO-1 if it's less than 8,000 feet or so. Assumed temp varies; if it's hot or the plane is full, usually just a rated takeoff at TO-1 or TO-2. CLB with the most aggressive derates possible on the GE 34, at least on our opspec, is always lower than any TO thrust. I often think they added a few too many feet to the 170 platform...
 
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Starlionblue
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Re: Can all jetliners take off at a climb thrust setting if they are lightly loaded?

Wed Sep 08, 2021 7:19 am

bluecrew wrote:
BoeingGuy wrote:
a320fan wrote:

Not uncommon on Boeing aircraft. For example, I believe EK have an SOP to use full climb thrust in the 777 when above max landing weight. Unless you’re really heavy or going off a limiting runway, in a lot of cases this will mean the climb thrust setting is actually above the assumed temperature dératé used for takeoff.


Emirates has an option on the 777 that allows up to a 40% Assumed Temperature Thrust Reduction on the 777. IIRC, NZ has it also. That’s a lot of reduction. That is likely below the three climb thrust settings. A maximum of a 25% reduction is standard.

FYI, an Assumed Temperature Reduction is not properly called a “Derate”, although many including myself tend to use that term loosely. Fixed Derates are “Derates”. Assumed Temp is a “thrust reduction.”

I can't even imagine that... that's a huuuuge reduction in thrust.
Double Derate in the 737 is already pretty performance limited and that's a loss of 18% or so in klbs.

The E190 likes standard TO-2 on longer runways, TO-1 if it's less than 8,000 feet or so. Assumed temp varies; if it's hot or the plane is full, usually just a rated takeoff at TO-1 or TO-2. CLB with the most aggressive derates possible on the GE 34, at least on our opspec, is always lower than any TO thrust. I often think they added a few too many feet to the 170 platform...


The TOW range on a widebody in day to day operations is considerably larger as a percentage of MTOW than on a narrowbody. The minimum takeoff weight can be less than half the MTOW.

Compare a 777 doing TPE-JFK with one doing TPE-HKG.
 
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AirKevin
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Re: Can all jetliners take off at a climb thrust setting if they are lightly loaded?

Thu Sep 09, 2021 2:00 pm

FlapOperator wrote:
AirKevin wrote:
FlapOperator wrote:
The MD-11 will set a Flex thrust via the FMCs to the autothrottles.

Usually the detents are flexible in their actual output, versus some kind of preset value.

I think we're not talking about the same thing. The Airbus appears to have physical detents on the thrust levers, and it doesn't appear to be the case on the MD-11, as seen here.



On the MD-11, to set your flex thrust for takeoff, you set that into the FMC. During takeoff, you can hit the auto-throttles, which will then use that data to clutch the actual handles into the correct thrust setting.

As you note, the 320 family has a number of detents, but those numbers are temperature influenced as well, with flex power being a derivative of a nominal max temperature.

In both cases, shoving the thrust levers/throttles all the way forward will give you max blast.

Yes, but my point is that you don't have physical detents on Boeing or McDonnell-Douglas jets like you do on the Airbus. You hit the auto-throttle and it pushes the thrust levers up to where it needs to go to achieve the required thrust level. I only mentioned this because the initial two replies mentioned moving the thrust levers from the take-off thrust detent to the climb thrust detent. On the Boeing and McDonnell-Douglas jets, those detents don't exist.
 
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AirKevin
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Re: Can all jetliners take off at a climb thrust setting if they are lightly loaded?

Fri Oct 08, 2021 7:50 pm

Here's an example of where climb thrust is higher than take-off thrust.

https://www.youtube.com/watch?v=34JYVr3EYMI

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