737 Takeoff Question

[GAJ52 54]

During a takeoff from Heathrow today, I had the HDG selected to the rwy QDM, A/T and F/D armed, takeoff power set using the TOGA switch. All was fine climbing at V2 + 10 until 1000' when I selected HDG then A/P A (CMD A). HDG captured nicely holding the rwy hdg and the SPEED switch lit up on the MSP with V2+20 selected as the required speed. The problem was the aircraft slowly pitched up to 20 degs and the speed dropped until the stall indication came on - what happened ??? Why didn't the A/P maintain the selected speed with the A/T on and SPD light illuminated on the SPD switch.Glen Coyne

[Guest tmetzinger]

you're sure the autothrottles were on?If you can duplicate the problem, please do so and take a screenshot so we can see what the AFDS modes are.

[crvm 0]

>During a takeoff from Heathrow today, I had the HDG selected>to the rwy QDM, A/T and F/D armed, takeoff power set using the>TOGA switch. All was fine climbing at V2 + 10 until 1000'>when I selected HDG then A/P A (CMD A). HDG captured nicely>holding the rwy hdg and the SPEED switch lit up on the MSP>with V2+20 selected as the required speed. The problem was>the aircraft slowly pitched up to 20 degs and the speed>dropped until the stall indication came on - what happened ???> Why didn't the A/P maintain the selected speed with the A/T>on and SPD light illuminated on the SPD switch.>>Glen Coyne You takeoff technique. 1] You don't fly V2 +10 but V2 +20+ with V2 +15 the MINIMUM SAFETY SPEED. Tyhe F/D are guiding pitching @+20 which you should be following. 2] The MCP SPD always jumps to +20 knots on the window when one selects a CMD in TOGA. 3] Not sure what happened on this particular flight since we cannot see all that went on to answer other than what you stated.Best Wishes,[h4]Randy J. Smith[/h4]http://www.rawbw.com/~bdoolin/shinault/southparkcartmad.gif[h3]PMDG 747![/h3]Caution! Not a real pilot, but do play one on TV ;-)ASUS KV8 DLX | AMD 3200 64 | 1 GIG PC 3200 DDR | GIGABYTE 5700 ULTRA | ViewSonic VP192b 19" |

[GAJ52 54]

Thanks for the replies.I have tried to reproduce the departure for a sreenshot, but now when I select HDG then CMD A at 1000' (during a TOGA taleoff), the LVL CHG and N1 switches illiminate and NOT the SPEED switch, resulting in the aircraft climbing normally.If I can reproduce the original problem I will capture it in a screenshot.Thanks againGlen Coyne

[crvm 0]

Yes LVL CH is the default pitch mode in TOGA...Best Wishes,[h4]Randy J. Smith[/h4]http://www.rawbw.com/~bdoolin/shinault/southparkcartmad.gif[h3]PMDG 747![/h3]Caution! Not a real pilot, but do play one on TV ;-)ASUS KV8 DLX | AMD 3200 64 | 1 GIG PC 3200 DDR | GIGABYTE 5700 ULTRA | ViewSonic VP192b 19" |