CX flaps settings

[b8z]

Hello

Can i ask what the standard take off flap setting is for take-off and landing on the 744 pax and freighters please.

Thanks
B8Z

[Sand Man]

Are you talking about FLAP or FLAPS settings? In CX they are two different things

[F_one]

He's asking for the Flap setting on 744, which in CX case is correct (I think). FlapS is the preferred term for the Airbus fleet.

(sic)

[jetset]

20 or 10 according to performance calcs.

Tends to favour 20.

Edited for typos!

[moosp]

And then the interviewer is going to ask them, yes but why do we sometimes use flap 10 and sometimes flap 20? A question that is (a) irrelevant, as we do not get a choice, "Computer Seyz No"" and (b) the interviewer is one of the 10 people on the fleet who knows the answer.

Something to do with segment climbs so we can take off with even less thrust than is sensible.

Grizzle over....

[dkul]

For landing Flap 30 is standard however Flap 25 is approved also which is more usual for windy/gusty conditions or very light weights.

[sodapop]

Step 1: Feed runway info/conditions and meteo data into the computer

Step 2: Computer looks for the highest assumed temperature from either F10 or F20. In other words, lower thrust. whichever gives the highest assumed temp wins.

Step 3: In case of both F10 and F20 giving the same assumed temp, then the computer looks at which gives the highest RTOW (regulated takeoff weight)

Step 4: In case both F10 and F20 give the same RTOW, then F20 wins.

Note: If the computer is not used, using published tables always uses F20.

[spleener]

Sodapop is correct, however in SIMPLISTIC terms:

F20 generally better when runway length limited
F10 generally better when obstacle limited

Note that you GENERALLY become length limited for a given thrust setting before becoming obstacle limited - therefore F20 is USUALLY generated from the computer if the optimum [default] setting is requested.

ie: at low weights/long runway F10 MAY be generated. at High weight/ shorter field length F20 is USUALLY generated.

That's enough for the interview.

Note: the PILOT can elect to override the optimum setting by inputting either 10 or 20. For one example; x-wind conditions at max thrust derate [lowest takeoff thrust setting] , the pilot may elect to use Flap[s] 20 to provide a further buffer against possible tailstrike.

Hope that helps b8z

[b8z]

thanks for all your replys

b8z

[jonathon68]

In the good-old days on the 744, F25 was the standard landing flap. F30 was only used for shorter runways (such as Kai Tak 13), since it resulted in a higher fuel burn. However, we also used to fly Vref +10.

After the 19th hole incident in BKK by a southern hemisphere airline, we went to a standard F30 landing with a Vref +5 (with corrections).

For take-off, it is F10 or F20 based on weight - runway - environmental performance etc.

For the 777.

Landing is Flap 30, with Flap 20 for S/E.

Take off is normally F5, with F15 or 20 at higher weights and with tailwinds etc.