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-   -   Crosswind Landing Accident. (https://www.pprune.org/accidents-close-calls/656202-crosswind-landing-accident.html)

Speed_Trim_Fail 7th May 2024 05:02

Airbus FCTM for my type recommends a crabbed approach with the flight deck positioned over the runway centerline, with the rudder used to align the aircraft during the flare, and roll input if needed for a small degree of “wing down” particularly if a strong crosswind means only a partial de crab. Obviously the sidestick is in normal law laterally (i.e. demands a roll rate) at that point so the into wind aileron (to wings level) is essentially applied by the FBW, with fine tuning from the pilot if needed. I found the runway centerline part interesting in particular, my GA and Boeing experience being to be somewhat upwind of the centerline, however there’s a good video floating around that airbus did explaining how this works in practice, including plenty of videos.

I have heard of people aligning the bus earlier on and flying essentially a forward slip, however as this isn’t in the FCTM if something went awry one would potentially be on a bit of a sticky wicket - touching down with some residual crab angle is however permitted.

The Boeing FCTM I used to use said you could basically use a forward slip, a de crab in the flare or a fully crabbed landing, whichever you preferred - and I believe this is as others have stated true on many of their types.

PPRuNeUser0221 7th May 2024 08:56


Originally Posted by xetroV (Post 11650284)
For reference, this is how Boeing test pilots did it when demonstrating the max crosswind for the 777.

https://youtu.be/_z2LtHrn9Jw?si=HWx4zbWgoZGW-O-L

Good days, that is Chile. Now we do them in Texas. In any case, the 777 is pretty stable (and the 787 more so) if you, as the poster said, keep it simple. Avoid the sideslip, maintain the crab until 50 feet RA and then use the rudder but BE CAREFUL for sudden wing direction changes! And for the love of God, don't float!

PPRuNeUser0221 7th May 2024 08:57


Originally Posted by Speed_Trim_Fail (Post 11650594)
Airbus FCTM for my type recommends a crabbed approach with the flight deck positioned over the runway centerline, with the rudder used to align the aircraft during the flare, and roll input if needed for a small degree of “wing down” particularly if a strong crosswind means only a partial de crab. Obviously the sidestick is in normal law laterally (i.e. demands a roll rate) at that point so the into wind aileron (to wings level) is essentially applied by the FBW, with fine tuning from the pilot if needed. I found the runway centerline part interesting in particular, my GA and Boeing experience being to be somewhat upwind of the centerline, however there’s a good video floating around that airbus did explaining how this works in practice, including plenty of videos.

I have heard of people aligning the bus earlier on and flying essentially a forward slip, however as this isn’t in the FCTM if something went awry one would potentially be on a bit of a sticky wicket - touching down with some residual crab angle is however permitted.

The Boeing FCTM I used to use said you could basically use a forward slip, a de crab in the flare or a fully crabbed landing, whichever you preferred - and I believe this is as others have stated true on many of their types.

This is classic Airbus SOP in moderate to severe crosswinds on the A350 and A320/321: wing down just a bit to diffuse the air flow, touch down with one set of main landing gear first

RichardJones 7th May 2024 13:30


Originally Posted by Claybird (Post 11650704)
Good days, that is Chile. Now we do them in Texas. In any case, the 777 is pretty stable (and the 787 more so) if you, as the poster said, keep it simple. Avoid the sideslip, maintain the crab until 50 feet RA and then use the rudder but BE CAREFUL for sudden wing direction changes! And for the love of God, don't float!

Well put.and totally agree. I like the bit about avoiding float!

jimtx 7th May 2024 15:04


Originally Posted by Speed_Trim_Fail (Post 11650594)
Airbus FCTM for my type recommends a crabbed approach with the flight deck positioned over the runway centerline, with the rudder used to align the aircraft during the flare, and roll input if needed for a small degree of “wing down” particularly if a strong crosswind means only a partial de crab. Obviously the sidestick is in normal law laterally (i.e. demands a roll rate) at that point so the into wind aileron (to wings level) is essentially applied by the FBW, with fine tuning from the pilot if needed. I found the runway centerline part interesting in particular, my GA and Boeing experience being to be somewhat upwind of the centerline, however there’s a good video floating around that airbus did explaining how this works in practice, including plenty of videos.

I have heard of people aligning the bus earlier on and flying essentially a forward slip, however as this isn’t in the FCTM if something went awry one would potentially be on a bit of a sticky wicket - touching down with some residual crab angle is however permitted.

The Boeing FCTM I used to use said you could basically use a forward slip, a de crab in the flare or a fully crabbed landing, whichever you preferred - and I believe this is as others have stated true on many of their types.

A decrab is a slip. Yaw will bring a wing up unless opposite aileron is input to keep level. While inputting that aileron we also might overdo it a little to put the upwind gear down a little earlier than the downwind.

RichardJones 7th May 2024 15:30


Originally Posted by jimtx (Post 11650889)
A decrab is a slip. Yaw will bring a wing up unless opposite aileron is input to keep level. While inputting that aileron we also might overdo it a little to put the upwind gear down a little earlier than the downwind.

Indeed. All correct IMHO.

His dudeness 9th May 2024 07:40


once again it seems to indicate biz jet lack of handling skills, safety awareness, CRM and what not.
You are lucky that apart from missing handling skills, safety awareness, CRM and what not, I´m to polite to tell you what I think about you after this post.

Yes, you should apologize.

RichardJones 9th May 2024 08:19


Originally Posted by His dudeness (Post 11651853)
You are lucky that apart from missing handling skills, safety awareness, CRM and what not, I´m to polite to tell you what I think about you after this post.

Yes, you should apologize.

Totally agree. None of us are without faults. We can ALL learn from others misfortune.

1southernman 9th May 2024 17:06

The only machine I remember intentionally landing in a crab was the original Quicksilver Mx with foot pedal spoilers and rudder/elevator stick...With everything else I tried not to...:)

Shaman 9th May 2024 17:35


Originally Posted by Bergerie1 (Post 11631032)
If you haven't already listened to these RAeS podcasts of DPD talking about his career and doing certification tests on various aircraft types you really need to do so. They are excellent:- https://www.pprune.org/tech-log/6029...-aircraft.html

Fascinating interviews - thanks for posting.

BugBear 9th May 2024 18:32

Flight deck centered
 

Originally Posted by Speed_Trim_Fail (Post 11650594)
Airbus FCTM for my type recommends a crabbed approach with the flight deck positioned over the runway centerline, with the rudder used to align the aircraft during the flare, and roll input if needed for a small degree of “wing down” particularly if a strong crosswind means only a partial de crab. Obviously the sidestick is in normal law laterally (i.e. demands a roll rate) at that point so the into wind aileron (to wings level) is essentially applied by the FBW, with fine tuning from the pilot if needed. I found the runway centerline part interesting in particular, my GA and Boeing experience being to be somewhat upwind of the centerline, however there’s a good video floating around that airbus did explaining how this works in practice, including plenty of videos.

I have heard of people aligning the bus earlier on and flying essentially a forward slip, however as this isn’t in the FCTM if something went awry one would potentially be on a bit of a sticky wicket - touching down with some residual crab angle is however permitted.

The Boeing FCTM I used to use said you could basically use a forward slip, a de crab in the flare or a fully crabbed landing, whichever you preferred - and I believe this is as others have stated true on many of their types.

Howdy... With the flight deck centered, the mains are well to the Right (Left) of centreline, no? Any drift due crosswind when (correcting), and touching down will put all gear well off center, right?

RichardJones 9th May 2024 19:11

Correct. This is why I like to decrab early to ensure the aircraft is lined up. That is with the main wheels, straddling the centrerline, on touchdown

Fly-by-Wife 9th May 2024 20:56


Originally Posted by Speed_Trim_Fail (Post 11650594)
Airbus FCTM for my type recommends a crabbed approach with the flight deck positioned over the runway centerline,


Originally Posted by BugBear (Post 11652159)
Howdy... With the flight deck centered, the mains are well to the Right (Left) of centreline, no? Any drift due crosswind when (correcting), and touching down will put all gear well off center, right?

"Over" in this case, probably means "past" the centreline, which would make sense. Once the crab angle is corrected, the aeroplane will (hopefully) then straddle the centreline.

BugBear 10th May 2024 04:01

"Over" in this case, probably means "past" the centreline, which would make sense. Once the crab angle is corrected, the aeroplane will (hopefully) then straddle the centreline..." (FBW)I should think a more descriptive phrase would be
"The centre point of the main gear track, regardless of crab angle, should be tracking the runway centre line..."

Pilot DAR 10th May 2024 11:03


the aeroplane will (hopefully) then straddle the centreline
I'm not a big airplane pilot, so I must defer to the "big" procedures for flying them, in which I have not been trained. But, for those airplanes I do fly and train with, I try to greatly minimize techniques which involve "hopefully" in the late landing phase! My vision of a stabilized approach minimizes "hopefully", and last moment changes to the approach path.

RichardJones 10th May 2024 17:38


Originally Posted by Pilot DAR (Post 11652483)
I'm not a big airplane pilot, so I must defer to the "big" procedures for flying them, in which I have not been trained. But, for those airplanes I do fly and train with, I try to greatly minimize techniques which involve "hopefully" in the late landing phase! My vision of a stabilized approach minimizes "hopefully", and last moment changes to the approach path.

Indeed. Set yourself up early.

Uplinker 11th May 2024 09:41

Turboprops with high wings and high mounted engines can use the crossed-controls wing down method to stay lined up straight with the runway during finals and the flare.

Many big jets though, have low slung engines in pods relatively close to the ground, so pilots must be careful not to apply too much bank which would reduce the pod clearance.

Hence most big jets use the crab approach and de-crab during the flare.

safetypee 11th May 2024 18:00

"Turboprops with high wings and high mounted engines can use the crossed-controls wing down method …"

and
the jet 146/RJ, where the combination of a large fin / rudder with the high wing provided excellent wing down control.

Unfortunately most pilots were unfamiliar or uncomfortable with the technique, which was judged as an unnecessary burden on training - not prepared to demonstrate the technique, and that the simulator did not accurately represent the side forces and roll yaw interaction.

Few opportunities to gain experience in the conditions; which appears to be a similar problem with other aircraft. If inexperienced pilots have to use lower minima, how then are they to gain experience sufficient to qualify them - many simulators are deficient in the required fidelity.

RichardJones 11th May 2024 19:29


Originally Posted by safetypee (Post 11653435)
"Turboprops with high wings and high mounted engines can use the crossed-controls wing down method …"

and
the jet 146/RJ, where the combination of a large fin / rudder with the high wing provided excellent wing down control.

Unfortunately most pilots were unfamiliar or uncomfortable with the technique, which was judged as an unnecessary burden on training - not prepared to demonstrate the technique, and that the simulator did not accurately represent the side forces and roll yaw interaction.

Few opportunities to gain experience in the conditions; which appears to be a similar problem with other aircraft. If inexperienced pilots have to use lower minima, how then are they to gain experience sufficient to qualify them - many simulators are deficient in the required fidelity.

Agree, especially regarding the simulators I have sat in.

I have always been of the opinion, if you look after an A/C it may help, look after you.
U/C, tyres specifically. Landing with crab must be putting a lot of stress on tyres, not to mention, the whole aircraft. A disintegrating tyre is capable of bringing down an aircraft. Remember the DC 8* at Jeddah, some years ago and Concord.
When you abuse an aircraft, intentionally or otherwise, keep this fact in mind. Other people have to strap their backsides to it, following, your abuse.
-"Metal and rubber have a very long memory"

* We were iat the Jeddah, Movenpick, Airport Hotel on a crew layover, when we were talking to some of the crew of that ill fated flight, the previous day. It seemed to me, by the behaviour and the body language of at least one of the crew members, that some humans have a premionison of death. This I will remember, until I die.
The subsequent accident report would be high on my list of recommended reading.

EXDAC 11th May 2024 20:04


Originally Posted by Uplinker (Post 11653141)
Hence most big jets use the crab approach and de-crab during the flare.

Autoland crosswind limits are typically much lower than manual landing limits. However, I don't know of any autoland system that does not establish runway alignment before flare starts. Are there any?

Sperry/Honeywell systems typically enter ALIGN mode at 150 ft RA and FLARE mode at 50 ft RA. If a pilot always handles a crosswind differently than autoland how do they build confidence that autoland will actually work at the crosswind limit?



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