KELPkid From United States, joined Nov 2005, 3503 posts, RR: 3 Posted (1 year 3 months 1 week 15 hours ago) and read 919 times:
Hi,
Well, this question came up last night, as I was getting in my car for the commute home, and saw a 757 fly over, lined up for 28R at PDX, and noticed that the direction the nose was pointed and the aircraft's ground track were obviously out of sync (Columbia River Gorge Winds strike again... ).
At what point does the crew transition to hand flying? I'm assuming that the autopilot doesn't transition from a straight crab into a crosswind landing config. automatically for the flight crew...it was a beautiful, 100% VFR evening last night.
Rulebooks and regulations are made from paper...and they do a poor job at preventing metal from contacting rock-Ernest G
Phxpilot From United States, joined Jul 2005, 61 posts, RR: 2 Reply 1, posted (1 year 3 months 1 week 12 hours ago) and read 868 times:
It varies depending on numerous factors, but in my experience it is anywhere from top of descent to the minimum authorized autopilot use altitude. I used to generally click it off ~10,000' if VFR and when established inbound on the approach if IFR.
Starlionblue From Greenland, joined Feb 2004, 12935 posts, RR: 57 Reply 2, posted (1 year 3 months 1 week 11 hours ago) and read 853 times:
What I think KELPkid may have been alluding to is: When you go over to hand flight, can there be a bit of a jolt if there is a crosswind or such that the autopilot is compensating for?
If KELPkid was not alluding to this, I would like an answer anyway.
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Modesto2 From United States, joined Jul 2000, 2273 posts, RR: 12 Reply 3, posted (1 year 3 months 1 week 8 hours ago) and read 806 times:
I usually disconnect the autopilot when cleared for the approach. Other times, it just depends on how I feel. After a long day, I may keep it connected longer. If it's beautiful and I'm feeling fresh, I may disconnect just below 10,000.
If in a substantial crosswind situation, disconnecting the autopilot will leave the plane still in a crab, along the desired ground track.
AAR90 From United States, joined Jan 2000, 2798 posts, RR: 41 Reply 4, posted (1 year 3 months 1 week 6 hours ago) and read 782 times:
Quoting KELPkid (Thread starter): At what point does the crew transition to hand flying? I'm assuming that the autopilot doesn't transition from a straight crab into a crosswind landing config. automatically for the flight crew...it was a beautiful, 100% VFR evening last night.
Whenever they want to start hand flying, but never lower than the minimum allowed by their company operations and/or legal limits. For me... "normally" somewhere between 10,000'agl and 1,000'agl. Most airliner autopilots do NOT put in crosswind corrections, but some might as it is not an unheard of feature.
Quoting Starlionblue (Reply 2): If KELPkid was not alluding to this, I would like an answer anyway.
If the plane is not "in trim" at the time of AP disconnect, yes there will be at least some "bump." Even then, what tends to be perceived as a "significant bump" in the cockpit usually goes unnoticed in the cabin.
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CosmicCruiser From United States, joined Feb 2005, 1445 posts, RR: 8 Reply 5, posted (1 year 3 months 1 week 5 hours ago) and read 772 times:
Quoting Starlionblue (Reply 2): When you go over to hand flight, can there be a bit of a jolt if there is a crosswind or such that the autopilot is compensating for?
referencing your question regarding x-wind and a/p disconnect...no the jet is doing what you would be doing if you were hand flying anyway therefore no change in flight characteristics.
Quoting AAR90 (Reply 4): If the plane is not "in trim" at the time of AP disconnect, yes there will be at least some "bump."
KELPkid From United States, joined Nov 2005, 3503 posts, RR: 3 Reply 6, posted (1 year 3 months 1 week 5 hours ago) and read 772 times:
Quoting Starlionblue (Reply 2): What I think KELPkid may have been alluding to is: When you go over to hand flight, can there be a bit of a jolt if there is a crosswind or such that the autopilot is compensating for?
Yeah, I was minorly curious about that one I was also wondering if maybe, perhaps the autopilot did the work for you if you let "George" fly the plane that low...
Quoting Modesto2 (Reply 3): If in a substantial crosswind situation, disconnecting the autopilot will leave the plane still in a crab, along the desired ground track
Quoting AAR90 (Reply 4): Most airliner autopilots do NOT put in crosswind corrections
Thanks for the answer, gents.
Rulebooks and regulations are made from paper...and they do a poor job at preventing metal from contacting rock-Ernest G
KELPkid From United States, joined Nov 2005, 3503 posts, RR: 3 Reply 7, posted (1 year 3 months 1 week 5 hours ago) and read 768 times:
Quoting CosmicCruiser (Reply 5): referencing your question regarding x-wind and a/p disconnect...no the jet is doing what you would be doing if you were hand flying anyway therefore no change in flight characteristics.
So I guess that means that the autopilot is usually disconnected by the time you are getting down into the runway environment
Rulebooks and regulations are made from paper...and they do a poor job at preventing metal from contacting rock-Ernest G
Flyf15 From United States, joined May 1999, 6068 posts, RR: 15 Reply 8, posted (1 year 3 months 1 week 5 hours ago) and read 757 times:
At my airline, we cannot have the autopilot on below 400 feet on a visual approach or below 80 feet on a precision (ILS) approach.
When I disconnect the autopilot depends on the airport, the weather, how lazy I'm feeling, etc. Some legs I fly completely without ever engaging the autopilot... some legs I bring the autopilot on moments after takeoff and take it off moments before landing. Visual approaches (traffic patterns and other abnormal / non instrument approach type maneuvers) are much easier flown with no autopilot or flight director. Instrument approaches in hard IMC at night are usually easier flown with autopilot and flight director. I'll also use the autopilot when the crew is tired or workload is otherwise high... I feel it improves overall safety. Hand-flying the airplane is a lot of fun, but sometimes its just more work than I feel like doing.
For those asking about disconnects on approach. The CRJ autopilot is well, horrible, at flying glideslopes and localizers. Although, it is quite good at handling turbulence on approach. It over controls on glideslope and under controls on localizer. I often have to disconnect it early and handfly it due to unacceptable performance by the autopilot. As has been previously said, if it is not trimmed up, there will be a jolt of the yoke when it is disconnected but that is usually expected and quickly reacted to... not creating any noticeable change in aircraft attitude.
The CRJ autopilot is also very slow to react to commands. Very gentle is good for a smooth ride but sometimes you need to do something "NOW"... or something with more precision or creativity than the autopilot is capable of. In those circumstances, you must hand-fly it... although you can keep the flight director on if you want and let it catch up with what you are doing.
Well, I've rambled enough, hopefully some of this made sense.
CosmicCruiser From United States, joined Feb 2005, 1445 posts, RR: 8 Reply 9, posted (1 year 3 months 1 week 5 hours ago) and read 753 times:
Quoting KELPkid (Reply 7): So I guess that means that the autopilot is usually disconnected by the time you are getting down into the runway environment
Depending on the jet type and I refer to the one I fly you can just let it autoland if you wish and the wind is within limits. Most guys kick it off anywhere from 1000'-500'. Usually in high traffic areas keeping the a/p engaged allows both pilots to be more heads-up therefore hand flying MAY not be the most prudent decision but if conditions are right heck kick off the a/p and a/t, have fun..
PhilSquares From Ireland, joined Mar 2004, 3739 posts, RR: 53 Reply 10, posted (1 year 3 months 1 week 3 hours ago) and read 724 times:
Quoting CosmicCruiser (Reply 9): Depending on the jet type and I refer to the one I fly you can just let it autoland if you wish and the wind is within limits. Most guys kick it off anywhere from 1000'-500'. Usually in high traffic areas keeping the a/p engaged allows both pilots to be more heads-up therefore hand flying MAY not be the most prudent decision but if conditions are right heck kick off the a/p and a/t, have fun..
Same for me. If it's been a really long leg on the back side of the clock, the disconnect will happen closer to 500', other wise it's normally 1000'. The last 1000' are just about the only fun you get to have anymore!!!
Jetlagged From United Kingdom, joined Jan 2005, 1870 posts, RR: 7 Reply 11, posted (1 year 3 months 6 days 23 hours ago) and read 684 times:
Quoting AAR90 (Reply 4): Most airliner autopilots do NOT put in crosswind corrections, but some might as it is not an unheard of feature.
All airliner autopilots I've encountered put in crosswind corrections, certainly all the modern ones. Think about it, it's tracking the ILS localiser deviation, if there is any drift it will attempt to compensate. Modern autopilots tend to do this with a combination of sideslip and drift, rather than drift alone.
That being said I remember asking a 747-200 Captain about the performance of the autoland in crosswind conditions, because at that time the CAA required flight simulators to objectively demonstrate autoland in still air and crosswind. He said he had never seen it because CAT 3 conditions were almost invariably accompanied by very still air.
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