Vertical Speed bug?

Hello IFC,

I was doing an ultra-realistic flight from EHAM (Amsterdam Airport Schiphol) to LOWW (Vienna International Airport) on the Expert Server with the B737-700 and of course, encountered strong winds. Therefore, I decided to takeoff against the 29kts winds, made possible by runway 27.

However, when at rotation speed I rotated and waited for a bit then turned on my autopilot and set my VS to 800. To my suprise, it went nuts and made a super steep climb till I reached a dangerously low airspeed. (see the photo).

In annoyance, I ended to flight as I didn’t want to get any violations from this incident.

Does anyone know why the VS was like this?


Are you balanced correctly? Maybe you have more fuel in separate fuel tanks causing the gravitational pull downwards, which the A/P then counteracts by increasing the vertical speed.

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I was well balanced for this flight and did loads of flight preparation.

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So the takeoff angle was fine until you activated autopilot, correct?

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Indeed, it was.

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You had an air speed of 160kts, 0% trim and your AP was engaged too early.

You stalled. Simple.

Next time you try an “ultra realistic flight”, it could be worth making it realistic by hand flying it until you achieve manoeuvre speed which is when the aircraft is “clean” and able to turn safely.

Your Vr speed was miscalculated based on the wind gust. When it’s really windy give it an extra few seconds before rotating as if the wind drops, the speed of the air over the wing drops with it - meaning you lose lift.


This was because of the VS that caused the aircraft to climb too quickly and therefore lost speed in effect. Duh, buddy.

I lowered the trim to 0% as this was happening.

I rotated at 150kts (not including the 29kts headwinds) and had a load of 50%.

Without providing us a replay all we are going to do is make educated guesses as to what happened.

Depending on user input, just because you set your VS to 800, 400, 200… does not mean that the aircraft will always snap into that climb or descent profile. To me, it seems that your inputs were too aggressive at the time and you probably should have hand flown the aircraft before arming the autopilot within a few hundred feet of wheels up.


I was hand-flying it till around 260ft and only then engaged my autopilot.

You should be engaging autopilot between 4000-10000 ft Mate.

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Again, without the replay we are just spinning our tires.

I still believe that the user input was too aggressive and your aircraft was going into a stall. At that point you would have been better off applying pressure forward on the yoke, pitching your nose to gain more speed.

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Obviously my time here is wasted, apologies for trying to give you points that will help in future.

Good Luck @Levet

You’re acting a little sensitive buddy. I was just responding to you with what happened.

That’s what I usually do, but the wind gusts felt crazy and I thought my AP would handle it better than myself.

I did that at the end, but I felt like my flight had been ruined so…

Be careful in those strong winds. Don’t be afraid to hand fly the aircraft, the Casual Server is your best bet for mastering strong winds :)