tonyban
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Is The Autopilot On During Severe Turbulence?

Thu May 01, 2008 7:00 pm

Sorry if this may sound like a dumb question. During severe turbulence, do the pilots assume manual control of the aircraft or does Autopilot do all the work ? Having travelled many times between SFO and LHR, I've always wondered about this ? Thanks.
 
futurecaptain
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RE: Is The Autopilot On During Severe Turbulence?

Thu May 01, 2008 7:13 pm

Generaly no.

Severe turbulence is, well, quite severe. By definition the aircraft can be out of control. The autopilot will be constantly chasing the altitude and heading and all the pitching of the aircraft can overstress parts.

In severe turbulence the autopilot is off and you ride it out trying not to stress the aircraft too much.
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WESTERN737800
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RE: Is The Autopilot On During Severe Turbulence?

Thu May 01, 2008 8:25 pm

I've got about 1000 hours total flying time. The biggest plane I've flown is a Cessna 414, most of my time is in single engine stuff. The first thing I do in rough air is turn the autopilot off. I think they tend to overcompsenate in rough air which can easily lead to overstressing the controls.
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thegreatchecko
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RE: Is The Autopilot On During Severe Turbulence?

Thu May 01, 2008 8:25 pm

Or if you are REALLY lucky, the autopilot will disengage when you hit the first good bump. Had that happen yesterday, it definitely surprised me.

Checko
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AdamWright
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RE: Is The Autopilot On During Severe Turbulence?

Thu May 01, 2008 8:27 pm

TURB mode and go back to sleep... Zzzzzz
 
wilco737
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RE: Is The Autopilot On During Severe Turbulence?

Thu May 01, 2008 8:30 pm



Quoting TheGreatChecko (Reply 3):
Or if you are REALLY lucky, the autopilot will disengage when you hit the first good bump. Had that happen yesterday, it definitely surprised me.

Really? never happened to me! I have never experienced that the A/P disengaged on its own. On the 737 we put the A/P in CWS mode, then he just tries to maintain a certain pitch and keeps the wings level and not trying to chase the altitude all the time.
On the MD11F: just watch what she is doing! And as long as she is doing it well: just sit there and wait until it's over.

WILCO737 (MD11F)
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WESTERN737800
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RE: Is The Autopilot On During Severe Turbulence?

Thu May 01, 2008 8:32 pm

Another thing about autopitots. Expect them to fail/quit when you least expect it. A friend of mine was flying a small twin with people in the back, and the autopilot disengaed on its own. The airplane started a sharp turn, luckily he was about 6000 ft + agl when it happened.
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A342
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RE: Is The Autopilot On During Severe Turbulence?

Thu May 01, 2008 8:33 pm



Quoting WILCO737 (Reply 5):
On the MD11F: just watch what she is doing! And as long as she is doing it well: just sit there and wait until it's over.

Well, I guess that's easy if you don't have passengers complaining! Lazy guy!  biggrin 
Exceptions confirm the rule.
 
CosmicCruiser
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RE: Is The Autopilot On During Severe Turbulence?

Thu May 01, 2008 8:48 pm



Quoting WILCO737 (Reply 5):
On the MD11F: just watch what she is doing! And as long as she is doing it well: just sit there and wait until it's over.

WILCO737 (MD11F)



Quoting A342 (Reply 7):
I guess that's easy if you don't have passengers complaining!

The A/P is used even in a windshear event. It does a good job and the pilot monitors. Actually the pilot would come closer to overstressing the jet before this A/P.
 
saab2000
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RE: Is The Autopilot On During Severe Turbulence?

Thu May 01, 2008 9:01 pm

On the CRJ the autopilot is a real champ. It hangs on tight in the worst turbulence I have experienced, which would be strong moderate to severe turbulence. BTW, stuff doesn't really actually normally just fly around the cockpit in bad turbulence, but it is bumpy nevertheless.

The worst turbulence I ever experienced was in the SAAB2000 on the short hop between GVA and LUG. We were IMC and had the radar on, but showed nothing. Out of nowhere the airplane shook like the Almighty Himself were shaking it like a bottle of soda. About 20-30 seconds later it stopped. The autopilot kicked off and we lost 300 feet in seconds. Then it was over and I told ZRH Radar that what had happened and my voice was shaking....

We must have flown into an embedded CB that just didn't have much moisture for the radar. Anyway, normal policy is for the autopilot to be on in turbulence. And normally it hangs on just fine in commercial level transport aircraft.
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ftrguy
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RE: Is The Autopilot On During Severe Turbulence?

Thu May 01, 2008 9:40 pm

I fly a highly modified 707 with 737NG avionics. Our procedure is to keep the autopilot on during turbulence and maintain our turbulent air penetration speed. I've never had the autopilot kick off in any regime and it handles the turbulence quite well. The way our plane handles the turbulence, sometimes I can't even see the instrument panel clearly, so I much prefer the autopilot to fly through it.
 
mcdu
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RE: Is The Autopilot On During Severe Turbulence?

Thu May 01, 2008 10:02 pm



Quoting CosmicCruiser (Reply 8):
The A/P is used even in a windshear event. It does a good job and the pilot monitors. Actually the pilot would come closer to overstressing the jet before this A/P.

What kind of airplane are you flying? I have over 15,000 hours and have flown Boeings 777,747,767,757,737,727 and Airbus A319/320 on NONE of those airplanes doe you leave the A/P on during windshear.
 
wilco737
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RE: Is The Autopilot On During Severe Turbulence?

Thu May 01, 2008 10:09 pm



Quoting Mcdu (Reply 11):
What kind of airplane are you flying? I have over 15,000 hours and have flown Boeings 777,747,767,757,737,727 and Airbus A319/320 on NONE of those airplanes doe you leave the A/P on during windshear.

But on the MD11F you do! I am flying MD11F as well and it is indeed procedure to switch on the A/P or leave it on during windshear encounter! I had it in real life once and she does it amazingly good and precice!

WILCO737 (MD11F)
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PhilSquares
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RE: Is The Autopilot On During Severe Turbulence?

Thu May 01, 2008 10:23 pm



Quoting Futurecaptain (Reply 1):
Generaly no.

WRONG! The autopilot of most modern commercial transport aircraft will be able to handle the turbulence. It's left on until it clicks off. In over 18,000 hours of commercial ops I have only had the autopilot disengage once during turbulence.
Fly fast, live slow
 
A342
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RE: Is The Autopilot On During Severe Turbulence?

Fri May 02, 2008 5:34 pm



Quoting CosmicCruiser (Reply 8):
Quoting A342 (Reply 7):
I guess that's easy if you don't have passengers complaining!

The A/P is used even in a windshear event. It does a good job and the pilot monitors. Actually the pilot would come closer to overstressing the jet before this A/P.

No matter if it's on or off, that comment was a joke. Or at least it was meant to be.  fight 
Exceptions confirm the rule.
 
futurecaptain
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RE: Is The Autopilot On During Severe Turbulence?

Fri May 02, 2008 6:08 pm



Quoting PhilSquares (Reply 13):
WRONG! The autopilot of most modern commercial transport aircraft will be able to handle the turbulence.

I click the a/p off in severe turbulence. I don't fly a modern commercial transport aircraft and my a/p doesn't do great in turbulence.
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pilotpip
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RE: Is The Autopilot On During Severe Turbulence?

Fri May 02, 2008 8:54 pm

Nothing is worse than hitting CAT and having the A/P disconnect. Handflying while unable to see the instruments because the plane is shaking so bad and trying to put your shoulder harness back on is not fun.

Had that happen last week.
DMI
 
SlamClick
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RE: Is The Autopilot On During Severe Turbulence?

Fri May 02, 2008 10:43 pm



Quoting Tonyban (Thread starter):
severe turbulence

Taking your use of "severe" at face value I'd have to say probably disengaged, depending on aircraft type.

I don't think I've seen severe turbulence but maybe half a dozen times in forty plus years of flying all over the world. Most passengers will never experience "severe" turbulence. Turbulence is over-reported on a scale that varies with the inverse of the aircraft weight and pilot experience.

As mentioned above the Boeing CWS mode works pretty well for uncomfortable moderate to occasionally maybe severe. I also recall things like "Pitch Hold" mode on older Dougs. For FBW Airbus I'd surely start out with it on, and, as PhilSquares suggests, it'll click itself off if it can't keep up.

I've seen an occasion descending into Denver late at night where we not only punched off the autopilot but both of us got on the control wheels and tried to keep it in a safe attitude. It was, luckily, a ferry flight and the flight attendants hit the overhead on the first bounce but no injuries. The interesting thing was, we could not focus on the instrument panel. We thought it was shaking too much but later learned that G-forces (up and down) were actually distorting our eyes, changing the focal length in time with the bounces.

I've only PIREPped "extreme" turbulence once. I lost the molded wingtip and the last rib was ripped out of the wing. Meets the definition in my book. That was autopilot off. Well, not installed, actually.
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2H4
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RE: Is The Autopilot On During Severe Turbulence?

Fri May 02, 2008 10:50 pm



Quoting SlamClick (Reply 17):
Turbulence is over-reported on a scale that varies with the inverse of the aircraft weight and pilot experience.

I once saw a PIREP for severe reported by a C-5. I can only imagine what that ride must have been like...

2H4
Intentionally Left Blank
 
SlamClick
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RE: Is The Autopilot On During Severe Turbulence?

Fri May 02, 2008 10:55 pm



Quoting 2H4 (Reply 18):
I once saw a PIREP for severe reported by a C-5. I can only imagine what that ride must have been like...

Turned out to be non-meteorological. They'd forgotten to untie the airplane and were dragging Travis AFB behind them. Lots of buffet!
Happiness is not seeing another trite Ste. Maarten photo all week long.
 
2H4
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RE: Is The Autopilot On During Severe Turbulence?

Fri May 02, 2008 11:16 pm



Quoting SlamClick (Reply 19):
Turned out to be non-meteorological. They'd forgotten to untie the airplane and were dragging Travis AFB behind them. Lots of buffet!

Well, that explains the recent "seismic" activity in the midwest.

2H4
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Airbus_A340
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RE: Is The Autopilot On During Severe Turbulence?

Sat May 03, 2008 4:57 am



Quoting Mcdu (Reply 11):
What kind of airplane are you flying? I have over 15,000 hours and have flown Boeings 777,747,767,757,737,727 and Airbus A319/320 on NONE of those airplanes doe you leave the A/P on during windshear.

In Cathay, if the Autopilot is engaged during a windshear event, you keep it in.
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