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VNAV disengaged after rotation and other autopilot problems (B737-700)


tomandre

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Hi,

I've sumbled across some bugs during climbout, just after rotation on B737-700. The first problem is the fact that VNAV switches to LVL CHG just after autopilot engagement at 400 AGL. This wouldn't really be a problem, but the issue is the calculated V-speeds in the FMS.

Standard procedure is to set V2 in the airspeed window before departure, but for some reason if you climb out on V2 in this new 737NG version, the V2 is just above the minimum manuevering speed. This is definitely not very nice in case of an engine failure.

Another issue I've seen a few times is how the cruise altitude suddenly changes from i.e FL380 down to 2000ft in CRZ page, which makes the airplane level off at 2000ft - even though initial climb clearance as described in SID is inserted - i.e 7000ft.

Along the route, I've also had ANP which doesn't meet the RNP criteria en-route, as the airplane is slowly drifting off the LNAV path.

Hoever, well done on this project. This is the only major issues I'm facing right now, while I enjoy slight details such as the sound of fuel pumps set to on. I am also looking forward to flaps sounds driven by hydraulics, as going back to the cabin to enjoy the wingview every now and then is a must. A last input would be that the anti-collision light is very intense, while strobe light is rather weak. I'd prefer the oposite.

If there's any inputs or thoughts why I'm having these issues as described above, let me know. I am typerated though on B737, and have flown both 737-700 and B737-800 in my company - so my procedures and performance calculations should not really be the issue.

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