Reduced Versus Full Takeoff Thrust
 

Hi,

How often (approximate percentage if possible) do you use assumed or derated takeoff thrust versus full takeoff thrust?

Feedback appreciated.

A guess, but 85-90 percent of all takeoffs (EK 777).

Sometimes it's not much (say a 52 deg ASS TEMP on a 38 deg day), but TOGA thrust is usually only used on very heavy takeoffs (say DXB-LAX with a limiting load) or if there is a contaminated runway, or suspected windshear.

well... on the current turboprops reduced takeoffs are not approved, but on my previous bae146 time we used reduced takeoffs whenever possible, lets say 90% of the flights.

we had to perform one full thrust take off every 7 days on each aircraft for a performance check .

BA B747-400,

Note: retired 2 years ago

Reduced thrust almost every time.

The exceptions being places like Mexico City and Jo'berg, where fuel requirements and payload combined with the density altitude often required virtually full thrust (JNB maybe 1.72 EPR vs 1.74 max, but near as the same thing).

Some places (like MEX, JNB, GRU) also use an Aft C of G optimisation technique to maximise RTOW and gain payload.

Sometimes using a short runway eg Chicago, Cape Town or to avoid a delay also, but even on a long flight ex Singapore, you would normally derate somewhat to reduce from full thrust allowing 20,000+ hours on wing commonly for the engines.

Currently flying 737-800/700, nearly every take off (99,99%) is either reduced, derated or both.

Flying A319/20/21, every take-off done in rwys in excess of 7000' are done in Flex Temperature (reduced thrust). Except if windshear reported/expected.

Regards.

when you need to walk somewhere....if you have an option to walk or run...what would you do ?

Dash 8: in summer about 80%. The few times a non-reduced T/O is needed are usually due to limiting runways, which are not uncommon in my conpany.

In winter on the other hand, approx. 60-70% of takeoffs will likely be full power: icing conditions or deicing fluid present on the aircraft are among the items excluding a reduction in T/O power.

On Saab 340A, we use flex (between 92%-108% of rated power) on 99% of all takeoffs.

Are you asking Airline pilots or Corporate/charter pilots? Big difference...the 'why' is where the meat of the discussion lies.

At the airline and the government, DC-8 operator: Whenever not runway/climb limited, prohibited by environmental conditions or MEL/CDL.

USAF: heavy airlift, probably 70% of the take-offs were reduced, but the C-5 would require full thrust at many weights.

Corporate: about 50% or so in the Global, could be more if we put emphasis on using reduced power.

Reduced is the way to go probably 90'% or more: better margins, less wear, less likely to have a failure.

GF

We do it nearly all the time and since the advent of laptop performance calculations it can look pretty strange. I remember the tower asking us if we had had an engine failure the first time we used the laptop assumed temperature on a 4000 meter runway. Low visibility is another time we do not use it.

I use reduced thrust every time unless limited by company procedures and judgement based on prevailing conditions or situations.

Basically everytimes (B737NG).

Assumed temp. is used in most cases. Even in outside 36-40 Degrees Cent. we can still use 44 or 46 Degrees to cut the peak.

With the monitoring ability of Engine datas and maintenance from today the "standing time" of engines is increased significant the last 20 Years.

Whenever needed due to RWY, equipment failure or anything else: Full Thrust is used. Also once in 30 days was a proceedure I remember from a prevoius Employer.

Fly safe and land happy

NG

On the 787, we are expected to achieve and average 22.5% thrust reduction to avail of the most advantageous engine guarantees.

Mutt

You are flying the 787 ?

'Engine Guarantees'....gotta love that term. Was that coined by the blind mechanic with the blurry boroscope who's job it is to keep the engines up in the air? Tell me Mutt...how does he check if a there is bearing wear? Is there a special radar machine for that?

B737 classic/NG. Assumed temp reduced about 80% on the -300 and assumed/derated about 95% on the -800