# At what altitude or speed should i retract my flaps?

I’ve always retracted my flaps at 5500ft which usually works pretty well but i know it’s different for certain aircraft’s. I was just watching one of my youtube videos and noticed the pilot put up the flaps pretty quick as soon as we took off. Our plane was a 737-900er. So what’s a good altitude to retract flaps at?

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I usually retract flaps to 5 around 200kts, then UP at around 220kts…

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You should retract the flaps asap to minimize the drag and the fuel consumption. It has nothing to do with FL, just with the airspeeds. Like Benny said, all the flaps should be up by 220 KIAS.

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In every aircraft you can see a flaps diagram.

That shows exactly at what speed you can retract your flaps.

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If you want to see it good you need to set your texture graphics to high before your flight! Then it shows the diagram good enough to see it.

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This is actually the maximum speed for each flap detent. Not the speed to retract them.

Personally, for a 737 family aircraft, I prefer to retract to F1 at 190 and FUP at 205.

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If I didn’t have the retraction speeds memorized or in front of me, I’d retract flaps when the AoA starts flattening out to a relatively small angle (the amount of which you can eyeball after a little experience).

The shrinking AoA tells you the air is becoming energetic enough for sufficient lift generation without flap supplementation of the air curvature.

(obviously not done irl, but based on real principles by which the flap speeds are determined; even maximum extension speed structural limits are correlated with the AoA design range)

It also says on the schedule. You need to retrec your flaps under those speed. But just to know. You can choose by yourself whatever you like and where you feel comfertable. And it also can depend somethimes on how strong the winds are…

I usually start retracting at 1000ft since that when the AP is turned on and speed beginnings to increase. 5500ft is way too high you should be at 250KTS by then depending on weight obviously but normal weight flaps should be up at or before 3000ft.

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As the helpful individuals above have said, retracting flaps early on after takeoff is the most efficient. An acceleration height of 1,500ft is commonplace, sometimes lower or higher depending on a multitude of factors. I usually start accelerating around 1,000 to 1,500 and pitch for around 5° on the attitude indicator and with the 737 family, I usually clean up around 200-220 knots depending on weight. Hope this helps!

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I was asking myself: what’s a most important motivation for retracting flaps as soon as practical?

Assuming you’ve cleared ground obstacles and are committed to flight, adding “flight energy” at the highest rate possible seems to make sense (quickly expand safety margin while low, and impacts fuel and time efficiency).

“Flight energy” is a combination of both items in the topic title: altitude and speed. Altitude is potential energy and speed is kinetic energy, and each can be converted into the other and used to prolong flight without engine power. When low and heavy it becomes a factor.

Flaps reduce climb rate (correct me if I’m wrong), and increase drag, both slowing the rate of building flight energy, again, the rate of gaining height and speed.

When you reach the point where you’re committed to the sky, retract as soon as speed allows (at least min speed for the flap setting), to maximize the combined accumulation of acceleration and climb.

i only use max flaps 5 on takeoff

This is a website which I use. It has Max Flap Speeds for all the aircraft in Infinite Flight.

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