I have recently been flying a Bombardier CRJ 700 in a simulator and wondered how to derate the engines for takeoff.

I know how the takeoff thrust derating is selected in Airbus and modern Boeing aircraft via the (M)CDUs (see also How do pilots set the exact amount of thrust needed for a reduced power takeoff?) and I have also seen panels for setting engine modes including a flex temperature in aircraft like the MD-80 or the Avro RJ. However, I could not find anything like this on the CRJ (at least not in the simulator).

Can the CRJ even derate the thrust for takeoff? And if, how does it work?

I saw the thrust levers have detents labelled SHUT OFF, IDLE, CLIMB, TOGA, MAX POWER: CRJ Thrust Levers
(image source)

I assume TOGA would result in less thrust than MAX, but how is this selected?


1 Answer 1


Indeed the CRJ can use reduced takeoff thrust setting.

Flex power is selected by entering an assumed temperature on the PERF MENU page of the FMS CDU. If the FMS is not available, the assumed temperature can be entered on the EICAS menu page using the EICAS control panel.

It's set up using the CDU or the EICAS control panel. That control panel is on the pedestal aft of the thrust levers, between the radio panels. Do note:

The FLX indications on the EICAS menu page are only displayed if the FMS has failed or is not available.

As for the activation:

When programmed, the FLX power setting is activated by the FADEC when the thrust levers are in the TOGA detents.

Source: CRJ700 FCOM

Note on terminology:

Derate and assumed temp/flex are not interchangeable. In derate the takeoff calculations are done based on the derated value remaining the highest even when an engine fails. It can be used to lower the Vmcg/a and in turn the V1 in certain situations (related post).

  • $\begingroup$ I only looked under PERF INIT in the CDU, not under PERF MENU. $\endgroup$
    – Bianfable
    Commented Aug 9, 2019 at 8:10
  • $\begingroup$ @Bianfable: Does the sim have the EICAS option when you simulate an FMS failure? Also see added note. $\endgroup$
    – user14897
    Commented Aug 9, 2019 at 10:33
  • $\begingroup$ I'm not sure, I will have a look at it tonight, but I doubt it's accurate enough to even simulate an FMS failure. $\endgroup$
    – Bianfable
    Commented Aug 9, 2019 at 10:36
  • $\begingroup$ I checked: the sim allows setting the FLEX TEMP in the PERF MENU page as described and shows the reduced thrust on the EICAS, but as far as I could tell it does not allow setting anything via the control panel. $\endgroup$
    – Bianfable
    Commented Aug 9, 2019 at 15:18
  • $\begingroup$ Another related post to the last paragraph. $\endgroup$
    – TomMcW
    Commented Aug 9, 2019 at 18:42

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