Flaps 1 vs. Flaps 5 Takeoff

[Eddie]

I've been accustomed to using a Flaps 1 takeoff in both FlyJSim's 737-200 and PMDG's 737-800 (among other aircraft) to get a greater initial climb rate and save fuel. However, it seems that many real-world 737 operators do not use a setting below 5, even where runway length is not a restriction. Can someone explain why this is the case?

[ONDR4.cz]

I'm sure Jan will give you a fully qualified answer, but in the meantime, this is what the Flight Crew Training Manual says: "For takeoffs, when conditions permit, consider using larger flap settings to provide shorter takeoff distance. Larger flap settings also provide greater tail clearance."

Edited April 16, 2016 by ONDR4.cz

[jettojig]

I'm studying for my ATPLs currently and one of the "standard aircraft" we use (MRJT1) is obviously a 737-400. The performance data available only accommodates flap 5 or 15 take-offs, so perhaps it is a manufacturer-set limit?

[Morten]

Jan can probably explain this better than me, but I'll give it a shot.

F5 gets you airborne sooner, however, F1 will give you a steeper climb thus better obstacle clearance.  The reason is a higher flap setting gives you more drag - which means less thrust available to climb... .  This also means that F1 is the more economic choice - especially if the aircraft does alot of cycles each day.

M

Edited April 16, 2016 by Morten

[Eddie]

27 minutes ago, jiggyb2 said:

I'm studying for my ATPLs currently and one of the "standard aircraft" we use (MRJT1) is obviously a 737-400. The performance data available only accommodates flap 5 or 15 take-offs, so perhaps it is a manufacturer-set limit?

I believe that's merely for tailstrike clearance on the much longer -400, however performance data does exist for the -300 and other 737 models.

[Eddie]

27 minutes ago, jiggyb2 said:

I'm studying for my ATPLs currently and one of the "standard aircraft" we use (MRJT1) is obviously a 737-400. The performance data available only accommodates flap 5 or 15 take-offs, so perhaps it is a manufacturer-set limit?

I believe that's merely for tailstrike clearance on the much longer -400, however performance data does exist for the -300 and other 737 models.

[Litjan]

Hi guys,

nothing much to add to Morten´s reply. The -500s and -400s simply saved money during certification by omitting FLAPS 1 takeoff certification. Tailstrike concerns might have played a part for the -400s.

In general, FLAPS 1 will get you both a more quiet, faster and less fuel consumption climbout - so unless field lenght or close-in obstacles are an issue, FLAPS 1 is the choice for takeoffs.

Jan