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What pilots can do in X-wind Autoland?

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What pilots can do in X-wind Autoland?

Old 6th May 2007, 03:39
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Red face What pilots can do in X-wind Autoland?

Boeing planes' autoland system will do runway alignment, or decrab maneuver at about 500ft radio altitude in crosswind, then a sideslip will be established to reduce the crab angle and maintain plane on the localizer by what manual said, but it seems the A/P can not land plane on the runway centerline even the runway if there's strong crosswind (>20kt)which is within the A/P landing limitations(maybe <24kt),
I would like to know if the pilot can handle the rudder or ailerons to avoid plane blown to the downwind grassland with A/P engaging?
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Old 6th May 2007, 06:46
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I would like to know if the pilot can handle the rudder or ailerons to avoid plane blown to the downwind grassland with A/P engaging?
How or why or with reference to what can a pilot apply rudder or ailerons when they can't see the runway
The short answer is you either manual land or autoland - you don't mix and match
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Old 6th May 2007, 07:10
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i'm not a real world pilot but an enthusiast in flight sim and i can handle rudder padel during A/P crosswind landing below 500ft radio alt but ailerons still under A/P's control in microsoft flight simulator

i'd like to know if pilot can control rudder or ailerons when A/P applying decrab maneuver in real world boeing 747 or some other planes
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Old 6th May 2007, 08:13
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Grrr 2 or 3 axis A/P?

about which boeing models are we talking?
you mentioned a sideslip which would require a 3-axis A/P to operate the rudder.
i only fly the 'primitive' B737 with a 2-axis A/P + yaw damper.
judging from my sim experience you can "assist" the A/P using the rudder. it will counteract any input with the ailerons to maintain track or whatever.
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Old 6th May 2007, 08:30
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When on a autoland on the 757 cat 3b with 3 autopilots engaged you have no manual rudder control. after landing you need to disengage the autopilot to be able to taxi off the runway

Neil
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Old 6th May 2007, 08:32
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Have tried a 40kt X wind autoland in a 767 in the simulator and it works a treat.!
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Old 6th May 2007, 08:43
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thanks for all of you

Boeing 747-400, i think it's 3-axis A/P
In FS2004 a 747-400 developed by PMDG, before A/P applying runway alignment, A/P will conteract any input include rudder, but when start to decrab, rudder responsed my input, only rudder, but it's 3-axis A/P!

and by Boeing747-441 manual:
Runway Alignment and Asymmetric Thrust Compensation
AFDS controls the rudder during multiple A/P approaches to compensate for
crosswind landings and engine-out asymmetric thrust conditions. With LAND 2
or LAND 3 annunciated, A/P control of the rudder is active.
For crosswinds requiring more than 10 degrees of crab angle, runway alignment
occurs at 500 feet AGL. A sideslip of 5 degrees is established to reduce the crab
angle. This configuration is maintained until touchdown. The airplane lands with
the upwind wing low.

maybe something wrong with PMDG747

Last edited by bf109hartmann; 6th May 2007 at 09:11.
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Old 6th May 2007, 09:05
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so if A/P landing engaged, is there any deviation to runway centerline in strong crosswind?
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Old 6th May 2007, 10:58
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Autolands in low vis conditions are only permitted in very light winds, usually around 10kts x-wind max, so the crosswind landing problem is not very severe.

The actual x-wind autoland limit in clear weather is 25kts and I carried out an autoland in such conditions years ago and the aircraft, a B767-300, performed flawlessly. Maintaining the runway centreline was not an issue.

The only way to provide manual input during an autoland is to disconnect the autopilot. If you attempt to 'help' the autopilot it'll probably disconnect by itself which then presents you with another problem.

Regards.
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Old 6th May 2007, 14:54
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My 2 cents.
1st
you either manual land or autoland - you don't mix and match
2nd - Respect the company xwind limits or at least the manufacturer one (the company should be more restrictive).
3rd - If an autoland sys with rollout capabilty is not able to maintain rwy alignement within it's manufacturer operational limits what pilots can do is to address a report to operational, maintenance and engineering dept.

Enjoy
HVIII

Last edited by Henry VIII; 6th May 2007 at 15:57.
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Old 6th May 2007, 22:33
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All manufacturer's have to demonstrate the maximum wind conditions under which the autopilot can safely land the aircraft within the particular requirements (LOC & GS deviation for CAT II and Touchdown zone for CAT III). For example Transport Canada's Working Note give values for CAT II of 10 kt Tail, 15 kt Cross & 25 Kt Head winds as minimum values that must be shown.

If memory serves, the Boeing 777 ended up coming to Wichita from Seattle as they were able to find, & successfully land in, a 44kt crosswind. Considerable time & effort goes in to doing this testing - we ended up taking a CRJ to Newfoundland from Wichita just to get representative CAT III conditions.
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Old 7th May 2007, 02:49
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Lets look at a particular aeroplane, one which was designed from the outset as a CATIIIC machine, without compromises.
Of course, I referring to the first wide-body to qualify, the superb Lockheed TriStar.
Looking further, lets look at some possible malfunctions.
The TriStar was designed to be fail operational in all respects, and where this, because of some system abnormality, was not possible for whatever reason, then fail passive.
So, on final approach during an automatic approach/land maneuver, the runway alignment maneuver begins at 150 feet agl.
This is possible because the rudder has changed to parallel operation when approach land track was established, earlier on.
IF, for whatever reason, the automatic runway alignment maneuver did not initiate, the pilot simply applies whatever rudder is needed...manually.
Just depress the appropriate rudder pedal, nothing else.
The automatic approach/land maneuver continues as otherwise normal.
Another example.
Suppose, for the sake of discussion, that the 'flare' maneuver did not initiate.
All the pilot has to do is apply sufficient backpressure on the pole, and the aeroplane will roll right on...smoothly.
Now, I have been flying the L1011 for many years, yet I have never seen any of these modes of failure.
Why not?
Because, when these old airplanes were assembled at Palmdale, the quality went in, before the name went on...absolutely, positively.
Ah.....Lockheed
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Old 7th May 2007, 03:48
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what ? this is confusing though isn`t it ?

Am l right in thinking that a computer game merchant is discussing real time effects with a retired captain ?

And one who ( the former ) hasn`t a clue about secondary effects of controls ?

Jeez.
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Old 7th May 2007, 04:27
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Am l right in thinking that a computer game merchant is discussing real time effects with a retired captain ?
If you're referring to yours truly, non iron, be advised I ain't retired....yet.

Keep in mind that many folks who are not pilots nevertheless have a keen interest in aviation, and thru some of the computer FltSim products available now, more 'technical' questions are bound to crop up.

Always answered to the best of ability...from this end anyway.
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Old 7th May 2007, 05:36
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Flight deck forums. Tech log.

Absolutely no offence intended, but would you run that by me again please ?
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Old 7th May 2007, 07:53
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I'm not a computer game merchant

i love aviation and fly heavy metals

thanks for all of you
by what real pilots said, there may be difference between different aircraft in A/P landing runway alignment logic

Boeing machines conteract any manual input

but Lockheed Tri-star will interact pilot's compensation when decrab didn't apply without disengaging A/P

interesting
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Old 7th May 2007, 08:04
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Of course you do.

Wrong place maybe ?


Have a good bank holiday both.

Last edited by non iron; 7th May 2007 at 08:30.
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Old 7th May 2007, 08:32
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bf109hartmann -
I can tell you what pilots can do. Make lots and lots and lots of calls. Absolutely indispensable stuff. Just make sure there's no silence for even a second and you'll be well on your way.
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Old 7th May 2007, 14:36
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'Calls'...are they really necessary?

I wonder.

In the 'old' days, not all that many pilot 'calls' were made.
Why not?
Well, for one thing, and considering for a moment the L1011, all autopilot/flight director functions and modes are clearly annunciated, and visible to both pilots and the Flight Engineer.
So, the FD was generally silent, except for malfunctions.
For example, if the runway alignment mode did not begin, it was annunciated and only this malfunction would be called thus...'no runway alignment'.

Yes, I know, heresy by todays standards.
However, it worked for many years and surprisingly enough, most airplanes never crashed.
Going further, when I fly the L1011 now, I fly with folks who operated in this minimal diatribe environment previously...and what a pleasure it is.
Folks who positively know what they are doing, not being reminded every ten seconds.

Sometimes, silence is appreciated.
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Old 8th May 2007, 12:58
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if i could fly heavy machines in real world in the future, wish the A/P calls nothing only Radio Altitude "100...50...40......"

there are no ejection seats in those machines
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