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Slight Side-to-side Rolling During Flight  
User currently offlineGolftango From United States of America, joined Feb 2006, 314 posts, RR: 0
Posted (8 years 8 months 5 days 12 hours ago) and read 3532 times:

In two instances I've noticed the ac rolling right to left.

Once on a SAT to DFW flight aboard a DL 732. During the entire flight the ac rolled back and fourth. No one else seemed to notice, but it was pretty evident while looking out the window.

Again, last year aboard an AA MD80 while on finals to BOS from MSY. The ac started to incrementally roll right in three or four small motions, then the same back to the left, repeat. I became a little nervous during that flight.

So, what is the culprit? Autopilot?

[Edited 2006-03-23 19:56:41]

11 replies: All unread, jump to last
 
User currently offlineJamesbuk From United Kingdom, joined May 2005, 3968 posts, RR: 4
Reply 1, posted (8 years 8 months 5 days 11 hours ago) and read 3513 times:

Probably the auto pilot making corrections due to wind or just the wind itself, maybe it was the aircraft making a slight turn at a waypoint.

Rgds --James--



You cant have your cake and eat it... What the hells the point in having it then!!!
User currently offlineRamerinianair From United States of America, joined Nov 2003, 1486 posts, RR: 0
Reply 2, posted (8 years 8 months 5 days 11 hours ago) and read 3506 times:

I have noticed this on the A320.
It was very pronounced on the TO and Landing. When the Pilot was flying, the rudder application was not solid. It felt like the pilot was pushing down and letting go rapidly and the rear of the A/C was "wobbeling" back and forth.
I think it was only when the pilots was controlling the A/C. I think Airbus calibrates the rudders so that the sensitivity changes with the airspeed. Maybe when gaining or loosing altitude, the rudder deflection changes when holding the same pressure.
SR



W N = my Worst Nightmare!!!!!
User currently offlineKAUSpilot From United States of America, joined Jan 2002, 1959 posts, RR: 32
Reply 3, posted (8 years 8 months 5 days 11 hours ago) and read 3506 times:

In the aircraft I fly it is quite common as well. During cruise the airplane will often bank back and forth continuously, no more than 5 degrees to either side.

The culprits are the autopilot and the FMS, more specifically the way they interface with one another. When you have the autopilot tracking the FMS course, sometimes it gets the message that it needs to bank to maintain course when in reality it should just be holding the wings level.

If I recall correctly, the DL 732 you rode on likely doesn't have an FMS, in that case, it was probably the autopilot attempting to hold a course based off a land based navigation signal....sometimes these signals aren't precisely accurate, especially at high altitudes, therefore the autopilot will initiate a bank anytime the course signal fluctuates.


User currently offlineFlyingHippo From United States of America, joined Aug 2005, 705 posts, RR: 1
Reply 4, posted (8 years 8 months 5 days 11 hours ago) and read 3477 times:

Flying STL-LGA on AA MD-80 last Thursday, we had to circle around LGA a few times due to high traffic caused by high wind conditions which actually closed LGA for a while.

While we're in the holding pattern, the strong wind shook the MD-80 pretty good, I was sitting near the rear part of the plane and I could feel the big yaw movements, as well as the roll and pitch constantly changing.

It's nothing to be scared of, it's either the pilot or the auto-pilot constantly adjusting the plane to keep it on it's flight path and glide scope.

The good thing is that as we approached the runway, we were still very bumpy (I did get a bit nervous by then), but the wind calmed down right as the pilot flared for the landing. A great job by the AA pilot!.


User currently offlineManuCH From Switzerland, joined Jun 2005, 3012 posts, RR: 46
Reply 5, posted (8 years 8 months 5 days 10 hours ago) and read 3379 times:
AIRLINERS.NET CREW
HEAD MODERATOR

I always notice this on my flights on A320s and A330s. It's a slight back-and forth rolling (no more than 2-3 degrees, full cycle takes about 10 seconds), even in smooth air. Looks like the FMS/autopilot are compensating slightly all the time.


Never trust a statistic you didn't fake yourself
User currently offlineGolftango From United States of America, joined Feb 2006, 314 posts, RR: 0
Reply 6, posted (8 years 8 months 5 days 10 hours ago) and read 3330 times:

Thanks for all the input! FYI, that DL 732 flight seemed to roll more than 5 degrees each time. I wish I got the tail number.

User currently offlineHAWK21M From India, joined Jan 2001, 31702 posts, RR: 56
Reply 7, posted (8 years 7 months 3 weeks 6 days 15 hours ago) and read 3156 times:

Was the Yaw Damper working.
 Smile
regds
MEL



Think of the brighter side!
User currently offlineLGAtoIND From United States of America, joined Jan 2005, 490 posts, RR: 1
Reply 8, posted (8 years 7 months 3 weeks 6 days 14 hours ago) and read 3080 times:

If the pilot turns the yoke, the aircraft will roll. If the pilot moves the rudder pedals, the aircraft will yaw. Both of these motions are common on commercial flights, especially when landing in a crosswind.

User currently offlineL1329II From , joined Dec 1969, posts, RR:
Reply 9, posted (8 years 7 months 3 weeks 6 days 2 hours ago) and read 2942 times:

Quoting Golftango (Thread starter):
Once on a SAT to DFW flight aboard a DL 732. During the entire flight the ac rolled back and fourth. No one else seemed to notice, but it was pretty evident while looking out the window

If its constant its almost always an autopilot issue.


User currently offlineRubyMtn738 From United States of America, joined Jan 2006, 42 posts, RR: 0
Reply 10, posted (8 years 7 months 3 weeks 6 days 1 hour ago) and read 2900 times:

Funny you should bring this up, I just finished flying with SkyKing Airlines on N977UA a B737-200 and I encountered the same experience. I asked the captain about it and he indicated it was an issue with the autopilot. Spent 3.5 hours rolling like we were in a boat.

Ruby


User currently offlineOPNLguy From , joined Dec 1969, posts, RR:
Reply 11, posted (8 years 7 months 3 weeks 6 days 1 hour ago) and read 2875 times:

Quoting HAWK21M (Reply 7):
Was the Yaw Damper working?

First thing I wondered...

http://en.wikipedia.org/wiki/Dutch_roll

The yaw damper works to mitigate this, but sometimes they go inop and get deferred...


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