Using the 737-800/900 Flaps

Ground School Community Tutorials
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Introduction

Hi everyone! I’ve seen an increase in the amount of people flying the 737-800/900 on Live. Some of these people act like experts when they use flaps, others, not so much. This is a tutorial on how to correctly use flaps on the Boeing 737-800/900 aircraft.

Before reading this topic, I’d recommend reading through this tutorial on the 737-800/900, then coming back here for a more in depth explanation on flaps.

About the 737-800/900

The 737-800 is a short to medium haul aircraft made by Boeing Commercial Airplanes. The 737-800 is in service with a ton of airlines world-wide. The main operators of the 737-800 are Ryanair, Southwest, and United. The 737-900 is a stretched version of the -800, with more capacity. It has the same MTOW weight, even though it is bigger.

United%20737-800%20N35236%20(2)
United%20737-800%20N35236%20(2)4000×2666 1.77 MB

Here you can easily see the flaps on the 737-800.

Flaps on the 737-800/900

There are 8 flap settings on the 737-800/900, with each having a different angle. These different angles allow the pilots to control how much lift the wings generate. Here are the angles below.

Flaps 1 - 8°
Flaps 2 - 11°
Flaps 5 - 14°
Flaps 10 - 19°
Flaps 15 - 22°
Flaps 25 - 26°
Flaps 30 - 35°
Flaps 40 - 46°

As you can see, each flap settings have varying angles which produce varying amounts of lift. But, how do you use these in the correct airspeed?

Flaps and Airspeeds

You use different amounts of flaps in different airspeeds. If you want more lift, you need more flaps, and vice versa. Here are the airspeeds in which each setting of flaps should be used to prevent damage, and maximize lift.

Flaps Up - 210KTS
Flaps 1 - 190KTS
Flaps 5 - 170KTS
Flaps 10 - 160KTS
Flaps 30 - 130KTS
Flaps 40 - 120KTS

Flaps 2, 15, and 25 are not normally used during flight hence why they are not on this list. Flaps 5, 15 and 25 are primarily used for takeoffs.
In adverse weather conditions, taxi with the wing flaps up and then set takeoff flaps during your Before Takeoff checklist procedure.
When extending or retracting the flaps, use the next appropriate flap setting depending on whether you’re slowing down or speeding up.

Conclusion

I hope you learned something new from this tutorial! I went as in depth as I could while still being simple. If you have any questions about the 737-800/900, just ask, I’d love to answer them. Thanks for reading this, and hopefully we can all become better pilots together!

Picture is mine, use with permission only.
http://krepelka.com/fsweb/learningcenter/aircraft/flightnotesboeing737-800.htm#flaps
http://www.boeing.com/commercial/737ng/

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I love the way you labeled them! Simple yet instructional. Guess I wasn’t a pro using flaps 40 during very light weather conditions :)

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Great tutorial, Matt! I have one thing though. You wouldn’t really go down to 120 knots in the 737-800/900, would you? Pretty sure the landing speed for the 737-800/900 is 148-153 knots, therefore eliminating flaps 30 and 40, correct? Or would you just use flaps 30 for landing?

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Flaps 30 is used on most landings. And yes, you can go down to ~125KTS on landing. That doesn’t mean every landing you go below 130, but some you do. Every landing is different.

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I’m guessing it just depends on your weight, correct? I feel like anything below 140 knots is slow…I might be wrong though.

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Very informative! I could use this for when the next time I fly the 738 or 739.

One question: Why do you not taxi with flaps during adverse weather conditions?

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For the average (or typical, or no limiting factors) takeoff and landing with a B738 or B739, you’ll use Flaps 5 and 30 respectively. Final approach speed will be around 140kts with a landing speed around 135kts. You would need more flaps if the runway is short, with a max of 25 for takeoff and obviously full for landing or if you are really heavy.

It’s a little brief and doesn’t really explain some of non-typical scenarios well, but it’s a start for what you’re asking.

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Great tutorials. It makes me want to fly the 737 again. Maybe I can land it with out a tail strike.

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Wow, that is pretty interesting. My guess is the exposed flaps and bad weather don’t mix so they only put them down before takeoff. Assuming that they would also retract them a little sooner after takeoff too.

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I thought you used flaps 5 for takeoff?

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Flaps 5, 15, and 25.

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I think you can use 1 and 2 for takeoffs at insanely long runways too. I’m not certain though.

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Yeah you can, but it’s rare!

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I’ve never had the FMC spit out a flap setting of 1 or 2 for takeoff configuration in a 737. I’m going to have to figure out how to do that now, lol.

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Thanks, Matt. Are those air speeds or ground speeds?

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Airspeeds. Thank you!

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What are 2 degree flaps even for?

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When established on final, and gear down is called, pilots in real Life set flaps to 15 and decrease IAS accordingly.

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I’m sure it will answer your question.

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Lets not rely on numbers from other simulators. The V speeds inputted into the table should come from official sources (ie Airline Operating Procedures, manufacturer flight manual for the aircraft)

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