I fly with fspassengers and have a setting of a 1% chance of failure for any given flight. On this flight while on approach I gave the command for my first officer to lower the flaps down to 1. After a few seconds he announced that the flaps were not going down. I confirmed this and went to the overhead panel, flipping open the alternate flaps cover and flipping the switch to "down". Not having used this feature I expected the flaps to go down in increments, not altogether. They went down to 40 (unkknown to me) and with all that was going on my aircraft stalled. Autopilot disengauged and/but I was able to recover and land ok. With this experience I was wondering if someone could give me the procedure for this emergency in this aircraft (737-900).Thanks,Chris Porter

Alternate flaps will (or at least should) only be utilized if there is a full Hydraulic System A & B failure. In other words, if hydraulics are working fine and the flaps won't go down, alternate flaps won't (or at least shouldn't) do anything to help the situation. So your situation is a bit abnormal.Alternate Flaps will fully extend leading edge flaps/slats. They are all or nothing and there's no retracting them. Holding Alternate Flaps switch will VERY SLOWLY extend the trailing edge flaps. T/E flaps can be VERY SLOWLY (duty cycle is ~25 minutes) retracted by the same method. I'm not sure if this is correctly modeled in the PMDG - as you note, it might just send everything to flaps 40.Of course getting to the point of needing Alternate Flaps would require an A & B hydraulic failure. As was the case in your instance, there would certainly be a lot going on. Due to the systems loss, you would be flying manually, lowering the gear manually, and dealing with other issues. You'd want to be VERY careful of any flap asymmetry - if you went to alternate flaps and one side didn't respond, you'd be in big trouble quickly. Because of the inability to retract L/E slats, inability to retract flaps very quickly, and stuck with a down landing gear, you'd be operating in a relatively small performance window and had better get your first landing right because you would be unable to execute a proper missed approach.Considering that an A/B failure would probably be caused by or would result in significant damage, you might be just as well doing a flaps up landing. I don't have a Non-normal Checklist to know what is actually recommended.But in the sim, with this seemingly isolated failure of just flaps, I guess you'd just get to about flaps 15 speed, extend fully with alternate flaps, and then land normally.Jared Smith

Thanks, very helpful. Now I know what not to do with just a loss of flaps and what to do should I experience a full hydraulic loss. What I find interesting now is that it only took about 1 minute for the flaps to extend and after landing it only took a minute for the flaps retract. One unrealistic glitch with this fs aircraft I guess.Thanks,Chris Porter

Thanks, very helpful. Now I know what not to do with just a loss of flaps and what to do should I experience a full hydraulic loss. What I find interesting now is that it only took about 1 minute for the flaps to extend and after landing it only took a minute for the flaps retract. One unrealistic glitch with this fs aircraft I guess.Thanks,Chris Porter

One alternative is to land with no flaps. As long as you have enough runway, this shouldn't be a problem. But as mentioned above if you did lose flaps then you would most likely have a complete hydraulics failure. This changes the situation significantly and corresponding remediation procedures.

Seems like every LOFT or Recurrent Training involves at least a partial or Zero-Flap situation and there are several flap malfunctions per year, so it's a good drill to run.

Seems like every LOFT or Recurrent Training involves at least a partial or Zero-Flap situation and there are several flap malfunctions per year, so it's a good drill to run.

Yes, much more so than knowing the alternate flaps procedures. There is a much higher likelihood of needing to make a zero flaps landing then there is that you'll need alternate flaps (or at least that you'd be in a situation severe enough that alternate flaps would be needed).