Hello,
I am still looking for hands-on experience and information regarding Flex/Assumed-Temp and Derated takeoff scenarii. In particular, I would like to know what happens (or usually happens) when thrust is reduced after takeoff. I am aware that there might be multiple correct answers here, I'll just take them all :-)
So here is the scenario. I am looking and jet (and possibly turboprop) aircraft departing with the following sequence of events:
- compute flex/assumed temp and/or derate for current circumstances (normal day, long & dry runway, no obstacles in any segment of the climb)
- apply reduced takeoff thrust, roll, rotate, climb at V2+10 (noise abatement)
- at 1500ft AMSL, apply climb thrust, still flying V2+10
- at 3000ft AMSL, accelerate as planned.
From what I've read, if using a Derated setting, the TO *
AND* CLB thrust settings will be decreased from their max rated equivalents. So basically, at 1500ft, we would observe a thrust reduction (please correct me if I'm wrong).
What I don't know is: what happens at 1500ft in a FLEX scenario? What is the desired climb thrust set to? Is it common or uncommon to *
increase* the power to use, for example, MCL thrust after a FLEX takeoff?
And what happens later? If climb thrust is lower than MCL/MCT, I believe that thrust will, at some point, be increased to reach that maximum when the air grows thinner at higher altitudes: is that correct? When does that typically happen and how?
Again, I am aware that there might be different scenarii, and therefore answers, out there, and I am OK with that.
Many thanks for your feedback!
Best regards
--
Romain, a very curious ATC
