After takeoff problem.

[Guest 9946578123]

Hi,I got a very big problem.When I'm flying the 737-600/700/800/900 I get a problem after takeoff.This is what happens: I program the FMC turn on the flight director, right as it has to be, before entering the runway arm autothrottle and VNAV, on the runway I increase the throttles to 40% N1, then activate TO/GA, take off, at 400 AGL I turn on CMD 1 and then...suddently the aircraft starts pointing nose up very steep, starts to turn the elevator trims up and down exessively, putting the nose up and down again, with 40

[Guest 9946578123]

>Can enyone please help me with this (...) problem??!x( Sorry for the (...);) ...Toto

[Guest 9946578123]

If there is a other topic about this please tell me where.

[downscc 1,327]

It's hard to figure out what's happening... does it try to pitch up while you are manually flying (Trim)? Is your airspeed much higher than V2+15 before asking the VNAV to take over? I've had a few problems with the takeoff-to-climbout transition but it was usually my lack of experience with the sim. Review the normal operations procedures in the documentation and check for yourself that you are following those. Someone with more experience my be a better help, but I hope I gave you something to work with. Keep trying.

[Guest 9946578123]

When I activate CMD 1 it pitches the nose up very steep;and what I forgat is that the speed is under V2+15 and the LNAV and FL CHNG are activated.And I'll take a look in the manuals....Toto

[Guest D17S]

Could be that you are going so fast (and still accelerating so quickly) that Vnav is having to make too much of an adjustment to slow you back down down. Try this: Right after you lift off, use the nose of the airplane (pitch) to stay as close to V2+10 as you can. Pitch the nose up to slow down and pitch the nose down to speed up. Don't touch thrust. Let the AT handle that. This is called flying "speed on pitch." BTW, this is exacatly what the AP is going to do when you press the AP button. Try to have the airplane as stable as possible and as close to V2+10 as you can before you press the AP button. If you have to "ride the bronco" a bit beyond 400 feet to get things settled back to V2+10 (or +20), that's OK. Just make sure that airspeed and pitch are stable before you press the AP button. That should get you a nice, smooooooth handoff to the AP.

[Guest 9946578123]

Thanks I'll try....Toto

[Guest 9946578123]

Sam, I tried all of your solutions and help about 5 times in different situations but it just won't work.My experience with the 737 is quite high and before this problem I flew allready over 200 hours with the 737 and suddently on a flight from brussels to tenerife it happend.And it is not a problem with the airports because I tried it on several airports.Whould it help to reinstall the 737?...Totox( :-mad

[downscc 1,327]

<I'm not saying don't try.. nonthing else has worked; but if it were happening to me I'd sure would try to find some clues first. Let's get specific: What is the plane doing just before you engage the black box (speed, pitch, climb rate, things stable or changing?) Then, what does auto do (pitch up first, or slow down then pitch up)?Maybe we're swinging at windmills, it's up to you and gotta understand I'm not always in the forum.Here about the four engineers in a stalled car? The mechanical engineer said it was the fuel pump, the electrical engineer said it was the battery, the chemical engineer said they were out of fuel and the computer engineer said, "Let's all get out of the car and get back in and see if she runs!"

[Guest 9946578123]

>What is the plane doing just before>you engage the black box (speed, pitch, climb rate, things>stable or changing?) Then, what does auto do (pitch up first,>or slow down then pitch up)?Right after I take off and pitch up the nose to 8

[downscc 1,327]

The 15-deg pitch up isn't excessive, everything sounds okay. A 25-deg pitch up is starting to get excessive. What happens if you don't try to override the pitch command? My guess is that the elevator control for the AP is through the trim (it is on many aircraft), in which case you might be inadvertently forcing the nose down. Also, try derating the takeoff power. The only time I use max takeoff power is when I'm heavy, it's real hot etc. A little less thrust will decrease the pitch up... maybe.

[Guest Hawkeyeted]

>Hi,>>I got a very big problem.>>When I'm flying the 737-600/700/800/900 I get a problem after>takeoff.>This is what happens: I program the FMC turn on the flight>director, right as it has to be, before entering the runway>arm autothrottle and VNAV, on the runway I increase the>throttles to 40% N1, then activate TO/GA, take off, at 400 AGL>I turn on CMD 1 and then...>suddently the aircraft starts pointing nose up very steep,>starts to turn the elevator trims up and down exessively,>putting the nose up and down again, with 40

[Guest D17S]

The autostab trim is not automatic until the AP is engaged. If the airplane is out of trim (or if somehow, the model has become untrimmable) this could happen. If trim is too far out of whack, you might be in for a wild ride while the AFS's autostab trim system gets things sorted out. My experience is with Dan's. Agree about the derate too. Had a Boeing, 744 test pilot tell me he gets 27 degrees on light test flights all the time. With max TO power, ol' AFS might really have to dig in to get airspeed back under control.Hand fly V2, speed on pitch to 3-4000 feet then hand it over. Then just sit back and watch the action. Gotta love that reset button.

[Guest 9946578123]

Sorry for the VNAV actualy it needed to be LNAV....Toto

[Guest 9946578123]

Sam and Dan, I'll try your solutions and let you know if it works....Toto