What flap setting to choose for takeoff?

[victorlima01 2]

Hey all. First off I would like to congratulate the PMDG folk for creating the most perfect add-on I've ever seen. I often fly the jumpseat with my uncle who's a boeing captain and I've never felt so close to actually flying a jet as I do with the PMDG 737. As I heard the altitude callouts on my first landing I was suddenly trasnported back to a real Boeing's flight deck. Great job!Now on to the business at hand. I gotta a couple of questions reagrding the 737's standard operaitons. First off, I would like to know on what should I base my flap setting for takeoff and landing. For example, I know for a fact that in the 777 they often opt for a flap 15 setting in light weights to avoid a tailstrike. Otherwise they use flaps 5. I would like to know when to choose flaps 5 10 or 15 in the 737-600 and 700. I know meteorological conditions runway lenghts and obstacle clearance and aircraft takeoff weight all play a hand in this; but I would like to know how to put them together and come out with the correct flap setitng. One more thing, I would like to know how the speed tape behaves during a takeoff. Once again to use the 777 as an example. Prior to takeoff, Vnav is armed and the f/d coupled with the autothrottle (not withstanding whether the a/p is on or off) automatically keeps V2+10 (or 15 can't remember) untill the accel height where it goes up to 250kt and the airplane than accelerates accordingly to maintain that speed. Throughout the acceleration the pilot retracts the flaps as the aircraft passes through the last flap setting's maneuver speed. I said all that just because I've been trying to takeoff in the 737 in the same manner but things aren;t working out perfectly. What is the airspeed that the 737 initially keeps - the one set in the MCP? If so, does it than adjust automatically to 250kt passing accel height? When should I arm Vnav and select a/p on?Sorry for the long post full of useless info but I just felt like writing. Once gain, thank you so much for such a great product. Cheers, Victor (private pilot SBRJ)

[crvm 0]

TO Flaps are SOP dependant and also based upon specific runway/conditions. Generally, in the United States, flaps 5 is the most common selection. You can use flaps 1 on the 600-700 though and some carriers use it more than 5. The NG is not very limited for performance even at high temps like you find at Las Vegas. You set V2 on the MCP. A/T and F/D ON. You advance the throttles to about 40 N1 and then push TOGA (located on the LEFT MCP SCREW). The F/D will pitch "after" initial liftoff for V2 + 20 (AT 80 knots or so it will pitch for 15 degrees) this is NOT a rotation command but an initial pitch to get to at 2.5-3.0 degrees pec sec rotation then it will advance the F/D to the V2 + 20 once established in the climb. VNAV is not armed or can be on the ground on the NG. You can arm LNAV if the LNAV criteria is met. If you select an autopilot while in TOGA the default pitch mode will be LVL CH. It's best to manually fly and cleanup/BUG UP SPD then engage the A/P. [h4]Randy J. Smith[/h4]

[victorlima01 2]

Thank you so much Randy, you've been great help. Now just a final question. For shorter runways do you suppose taking off with flaps 10 or 15 are better than flaps 5 or 1 or do they create excess drag and lenghthen the takeoff run? Cheers, Victor

[crvm 0]

I've heard of using 10 in such cases but there are not too many rwys that short. The limiting factor or one limiting factor is rotation that is too slow, not more flaps. I believe that flaps 10 gives you a few inches more clearance at least on the 800, I assume this also is relevent for the other NG models. Tail stike has been a issue with AA but in these cases excessive correction for crosswind and too quick a rotation were the major contributing factors.[h4]Randy J. Smith[/h4]

[Mats_J 2]

Victor,As you imply, there's a sweet spot for flaps usage. More flaps will create more drag but will also give you lower take off speeds. In the real world your weight is as important when it comes to keep you on the runway you are at. I would say that you will hardly see a -600/700 take off with a flaps 15 configuration. But it's almost impossible to answer your question with a YES/NO type of answer. THere are too many viariables for it to be that easy.Hope it helps,

[victorlima01 2]

Thank you Mat and Randy (once again!) Well, I only ask because where I live there's this crazy airport SBRJ (rio de Janeiro) where 737s come and go every 10 minutes and the runway is only 4341 ft long, and believe it or not there's a monstrous rock about 1300 ft tall only 2NM directly in front of the runway. Sometimes the Varig flights takeoff pretty heavy (for the RWY in use) and the temperature is usually above 85F. So as you can see, I have some reason to believe these pilots probably elect to takeoff with more flaps tahn usual... :)

[Guest diajohn2]

AT the AVSIM conference using the United 735 simulator they always use Flaps 1 for takeoff. Their style is just to activate the leading edge and not increase any drag. I saw this with two diffent flight instructors in two different 735 sims.