Expedite Climb

[Noise Unit]

Where in the world are flight crews encouraged to get as high (high as in altitude) as they can as quick as they can in order to avoid being held down at non-optimum altitudes once in cruise?

I have heard mention of the following:

i) South-bound flights from SE Asia into Indonesian airspace
ii) North-bound flights from JNB

Can anyone confirm the above or indicate any others?

Are there any similar issues for flights entering trans-oceanic track systems?

Thanks for any help.

[Noise Unit]

Given that this post, and a previous one concerning climb performance (particularly CLIMB derate policy), have recieved little comment, I would be grateful if people could indicate which of the following statements is true.

i) No-one has any opinion on this subject of climb performance and CLIMB derates - hard to believe in todays economic environment

ii) Every operator uses full MCL rating on every climb irrespective of aircraft type, weight, flight condition and local ATC restrictions

iii) No-one is interested in climb performance and CLIMB derate (a risky option to include as I'm sure it will be the subject of some very clever and cutting sarcasm)

I would be even more grateful for any information on the subject

:D

[Notso Fantastic]

Crews are encouraged to follow their flight plans which assume an ideal world with no competition for flight levels. In practice, crews learn when it is better to climb higher than desired earlier in order to have an optimum level later in the cruise.
It happens in Big Airways out of HKG homebound at night, SE Asia homebound (especially), India homebound, Africa homebound, and southbound approaching the N African coast. Very often we are just too heavy to manage it.
The 747-436 default uses reduced thrust up to about 25,000' when full thrust cuts in, so reduced climb power has evaporated at that stage. There is a further reduced power setting that must be manually selected and significantly reduces power, but if you are scratching for maximum climb, it is of no use.
We are at all times conserving our engines, and not keen to whack full power out of them.

[SuperRanger]

we fly south into indonesian airspance and north (actually north-east) from JNB regularly. we seem to be able to get our desired level most of the time.

one area i can think of requiring one to think of climbing above optimum to avoid getting caught low is eastbound from turkey into iran. because west of turkey, you have the luxury of RVSM levels but not in iran. therefore, it is advisable not to be caught cruising at a non-RVSM level prior to iranian airspace. to make matters worse, you also transition from a BRNAV area into non-BRNAV requiring 10-min separation (officially at least as over the last one year they have tried to accomodate acft down to even 5-6 mins separation)

SR

noise unit,

i think i might have misunderstood your earlier question. our procedure on climb derate is related to selection of derate-TO. once a derated-TO thrust is selected, then the appropriate derated-CLB will too be selected. we are then not to alter the CLB thrust selection (select a higher CLB) as this could mess up the noise abatement procedures out of certain noise sensitive airports.

any changes in CLB thrust when in the climb are usually ATC related.

SR

[Noise Unit]

Many thanks for the above comments.

I understand that CLB derate on some Boeing FMS is defaulted to the TO derate, but that alternative CLB settings can be manually selected.

This is probably logical for most operations as aircraft weight is a major factor in the choice of both TO & CLB derate. However, TO derate is also highly dependent on the available runway, so mismatches could occur.

QUESTIONS
1) Do Boeing crews generally accept the CLB derate defaulted to the TO derate? Or are other criteria used?

2) If so, what happens to the CLB derate if reduced TO thrust is selected using ATM?

My understanding of Airbus FMS is that the CLB derate is set independently to TO derate/FLEX.

QUESTION
3) Are TOW bands used to set default CLB derate levels, with min R/C criteria? Or, are default CLB derates applied to routes, but with option for changing due to min R/C or operational issues?

[SuperRanger]

noise unit,

i dont remember on any of the boeing acft i flew (B744, B772, B734), there's any mention of CLB thrust selection based on TOW. therefore, it lead me to believe generally boeing crew just accept the default CLB-derate associated with the derated-TO thrust. not sure how it's done on the airbus.

"If so, what happens to the CLB derate if reduced TO thrust is selected using ATM?"
not really sure how is it on the airbus but on the boeings, once you have decided your TO derate and Assumed Temp, you enter it into the FMC and the appropriate CLB derate will be selected i.e. CLB, CLB1 or CLB2. If i'm not mistaken, the CLB derate is based on the highest CLB thrust WITHOUT exceeding the selected TO thrust.

we do have a procedure where we manually amend the CLB derate. say for whatever reason you decided to takeoff using Full TO Thrust even when you can use TO derate (usually it's due to poor runway surface or slippery runway). then you find your TO derate and Assumed Temp and enter it in the FMC, check the selected CLB derate. Then, delete the selected derate and Assumed Temp to get Full TO Thrust. By doing so, the CLB thrust will default back to full CLB. we then manually select the required CLB derate.

SR

PS: on the boeings, we have 2 kinds of 'derates'. One is a takeoff derate i.e. TO, TO1, TO2 and the other is Reduced Takeoff using Assumed Temp.

Takeoff Derates is determined by your TOW and selected through FMC. it is as if you put on a smaller engine. therefore, it reduces your Vmca and is recommended for Contaminated Runway. Tafeoff Derates should not be cancelled in an engine failure as it can affect your controllability.

from your derated TO, you can further reduce your TO thrust if weight permits, by entering an Assumed Temp into the FMC. this is called the Reduced Thrust. this reduced thrust can be cancelled and increased to your Derated TO thrust during an engine failure.

[quid]

>>Takeoff Derates is determined by your TOW and selected through FMC. it is as if you put on a smaller engine. therefore, it reduces your Vmca and is recommended for Contaminated Runway. <<

I'm struggling with the logic for this. Can you help me out? (Not the smaller engine part, but why it's recommended for contaminated runways).

:confused:

[SuperRanger]

hi quid,

when TO-derate is selected, the selected derate is deem to be the max. thrust limit for that takeoff. due to the lower thrust, therefore, Vmca is lower (less yaw in an eng fail scenario). on a contaminated runway, as less traction is avail from the nosewheel, a lower Vmca is always desirable. you are not allow to reduce TO thrust further by Assumed Temp though. i believe boeing do have a chart showing the benefit of using TO-derate on a contaminated runway, just can't remember where i put it. anyone else seen it?

SR

[swish266]

Had a funny one at DXB a few years back.
It was Feb/March and we were not aware of a very pronounced low-level inversion. As far as I can remember temperature diff was almost 15 deg C! That is to say it went from 15 to almost 30 by 2000' AGL.
We were at about 160 tons on a B763 with GEs rated at 60.000.
AP was engaged before V-NAV.
When we selected V-NAV with a preselected Climb 1 derate power came so far back that we actually lost about 100' before we disconnected AP and reapplied THR manually.
Never again used Climb derate when heavy enough! Don't give s--t about SOP's.
Anybody else experienced something like this?
Comments from the "sandpit" guys most welcome!
Tnx!