The Boeing 737-900 lose speed. Is a Bug?

Ulan Dog · January 19, 2024 at 6:00 PM

Dear Ipacs team, I have set the route LMNF-EGCC, (Nice to Manchester). I perform the initial SID with all the required procedures simulating an initial altitude of 14000FT up to the cruising altitude of 37000ft. The problem is that by activating LVLCHG or V/S I can't reach 37000ft. and the Boeing 737-900 begins to lose speed until it reaches a stall. Can you check if this is a bug? Thank you.

My device is IPhone 12 pro max

Jet-Pack (IPACS) · January 19, 2024 at 6:39 PM Official Post

You need to fly faster during the climb and do not use V/S for climbing because you run the risk of stalling. 220 is too slow. If you fly slow drag increases. The stall speed tape does not yet show the increased stall speed, at 220kt at FL340 you are already close to stalling, 190 it definitely.

Either use VNAV or stay at around 300kt or Mach .75 or so.

When you fly faster more air is rammed into the inlet and the thrust goes up. And please don't use V/S for climbing, use FLCH or VNAV as you would in the real world.

Ulan Dog · January 19, 2024 at 7:17 PM

Thank you for your prompt reply!!

FL54 · January 19, 2024 at 10:43 PM

FYI, 300kias applies only below the crossover altitude of ~FL280. Above that you keep climbing with Mach, e.g. .75. With increasing altitude, IAS will decrease. At FL370 this is ~230kias.

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