Anyone had problems with autopilot?

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#1

So tonight, I was coming in for landing at KLAX, when the tower told me to make a go-around due to traffic. I was already on my glideslope so I had to push up the throttle and make a pretty hefty pull up. I had a negative VS set on the AP and when I swiped up to change it do a positive, it made it to 0 VS and then when the number was positive my aircraft basically started performing a negative drop in altitude? When I turned off my AP to fix the problem manually, the plane would not let me pull up.

In synopsis: My Vertical Speed setting on Auto-Pilot won’t let me enter in positive climb rates while on my glideslope.

Any idea why this is happening? Any solutions? Is this happening to anyone else? I was using the 737-700 if that helps diagnose the problem.

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#3

By no means should you be using that setting to go around. Disable it, reconfig your flaps and TOGA.

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#4

We’re you on APPR, I think the that you would need to turn that off first if that was the case?

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#5

No my Altitude was off, but for some reason when I turned it back on to set the pattern altitude everything was fixed, this has happened multiple times, I was not using APPR either (the 737’s don’t even have it.)

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#6

I don’t usually do that, but there was another plane on the runway so I was in a rush, and when I disabled it, it maunal didn’t work either.

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#7

You got me it’s time for some shut eye. Either case as Tim said above you should be flying manually regardless.

@Tim_B take it from here, I’m signing off.

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#8

Ok, I’ll be sure to do it manually next time. Thanks for your help!

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#9

This is the precice reason while killing the AP and making a manual TOGA makes the most sense.

Certainly, when pressed for time, disabling AP is gonna be a heck of a lot quicker than fiddling with VS

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#10

Ok. I’ll try doing that… still this doesn’t just happen when on glideslope, I’ve had it happen when cruising too. Any ideas?

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#11

I’m a little confused. At cruise, you use VS but not Alt?

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#12

You did say that you tried to pull up manually too right? The reason that didn’t go up could have been calibration.

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#13

Use manual, turn off autopilot.

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#14

You must disengage the A/P (autopilot) and then fly runway heading and manually TOGA for the instructed go-around. Fly with configurations until positive rate and go-around altitude is achieved like flying out of a wind-shear.

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#16

Hello

This happend to me to bit only one time.
Did you check your speed because in a sudden altitude change
You speed can change very fast so maybe you where stalling

I hope this helped

Verstuurd vanaf mijn iPad

#17

Did you change the altitude, as the VS is decided by the altitude input?

#18

What i was experiencing latly was, that on actice APPR mode the aircraft is mostly doing what it wants. Once it flew a good glideslope but i had to take over and G/A cuz it came in way to high on appr. Or another time it turned away from the runway curse just before minimums whrer i would have taken over.( i always activate it at the moment altitute and course are approx. The same to prevent it from taking evasive actions) these are the only problems i experienced with A/P or APPR Mode.

#19

Well I haven’t had the same kind of problem as you but sometimes when I’m on a flight in the A321 and I engage the autopilot the plane goes into severe oscillations. This happened when I was going well within the aircrafts speed limit when there wasn’t much turbulence. This hasn’t happened with any other aircraft.

#20

I have this problem with the a319 just after takeoff it is annoying and also when when I reach 30000 feet I just drop

#21

Perhaps practice Landings so you don’t need AP…

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#22

Part of my final approach checklist is to set the trim (with autopilot still on) so that the little pink bar next to the trim % disappears. This is so that if I need to disconnect the autopilot, the pitch doesn’t go wild.

Other than that, in such circumstances, I am always ready at the drop of a hat to hit the “A/P” button, disconnect the autopilot and hand fly the airplane on the go around.

In the real world jets I flew (Lears, Citations), we had a “TOGA” button - which would reposition the flight director - but nothing like that exists in IF, so hand flying the airplane using a specified pitch and power setting is whats needed to successfully do a go around.

My personal suggestion for Go Arounds while on short final in IF (take it or leave it:) -

  1. Disconnect AP (ensure trim is set while AP on so no pink bar shows)
  2. Pitch first (10-12 degrees)
  3. Apply takeoff power (98% N1)
  4. Positive Rate - gear up
  5. Retract one notch of flap
  6. Accelerate to somewhere around V2+30 (180 kts maybe?), retract flaps
  7. Fly missed approach course (follow ATC instruction)
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