B777 Cross Wind Landings
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B777 Cross Wind Landings
I have just transitioned from the B767 to the B777 about a year ago. Cross wind landings for the B767 seemed much simpler than the B777. I was taught the decrabbing method during the flare but it is fairly to get the technique spot on...mostly ending up in what seem to be crunchers. Luckily, even when logged into the technical log as suspected hard landings but thankfully the engineering division came back with negative QAR data which indicated any hard landings beyond the limit. However from the cockpit, the landings felt terrible! This is especially so if I couldn't decrab fully before touchdown. There was some residual crab angle at touchdown which was fully corrected after touchdown......the feeling I felt in the cockpit was a terrible sensation of a bad landing! However the engineering guys said that the verical g was only 1.58g and the side g was well within limits. Then why did it feel like an absolute cruncher? Hopin to be enlightened by the B777 gurus out there!
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Decrabbing fully during the flare is nice and dandy in steady crosswinds but fairly difficult to perfect in the real world with variable gusty crosswind on a hot day. This especially so when you only encounter such occasions infrequently and get to practise once annually on the simulator which probably cannot replicate real world environmental conditions during a hot gusty crosswindy day.
I would suggest crabbing down to about 500 ft AGL and then decrab early transitioning to a landing with the side slip method, touching down with the upwind gear first when the crosswind is 25kts or less. Above 25 kts, just bear with all the imperfections of an untidy decrabbing during the flare. Just bear in mind that during the decrab during the flare, you lose quite a bit of lift and would probably need to pitch up more, override the auto- retardation of the thrust levers just a tad to prevent a cruncher. Please understand I am no B777 guru; I left the B777 several years ago and I survived enough years on line operations on that equipment to share something here.
I would suggest crabbing down to about 500 ft AGL and then decrab early transitioning to a landing with the side slip method, touching down with the upwind gear first when the crosswind is 25kts or less. Above 25 kts, just bear with all the imperfections of an untidy decrabbing during the flare. Just bear in mind that during the decrab during the flare, you lose quite a bit of lift and would probably need to pitch up more, override the auto- retardation of the thrust levers just a tad to prevent a cruncher. Please understand I am no B777 guru; I left the B777 several years ago and I survived enough years on line operations on that equipment to share something here.
Last edited by bakutteh; 13th Jul 2010 at 04:58.
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Sigh, I have done a few crunchers myself. Luckily nothing above the limits as borne out by the QAR readings. Well yelena, take heart as you will improve with time. Like bakutteh said, it's pretty hard to get the decrab during flare technique right. I have overdone it a couple of times ending up with the nose pointing a tad to the downwind side with an awful sensation upon touchdown. I think bakutteh suggestion to follow the autopilot technique of decrabbing early and then sideslip to touchdown works well. I have never had a crosswind exceeding 25 kts, so I am not sure whether this technique work well or not in this case.
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Old Smokey, are you there?
There is a gentleman somewhere in the Lion City by the name Old Smokey who probably can share with you guys his immense experience on the B777. I believe he has written about his misgivings about landing without decrabbing on the B777 eventhough this has been demonstrated by Boeing test pilots.
The T7 undercarriage has rear steerable wheels which will castor to maintain airplane ground track upon touchdown when the aircraft nose is not fully aligned with the runway.
Personally, I find the triple very good in crosswinds. Up to 25kts I use wing down and over that I combine wing down with either landing with the rest of the drift still on, especially if wet, or an extra little decrab close to touchdown.
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Old Smokey, are you there?
There is a gentleman somewhere in the Lion City by the name Old Smokey who probably can share with you guys his immense experience on the B777. I believe he has written about his misgivings about landing without decrabbing on the B777 eventhough this has been demonstrated by Boeing test pilots
There is a gentleman somewhere in the Lion City by the name Old Smokey who probably can share with you guys his immense experience on the B777. I believe he has written about his misgivings about landing without decrabbing on the B777 eventhough this has been demonstrated by Boeing test pilots
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Next time you'll go in the box ask someone to do the landing and call up the flight control synoptic page and observe surfaces deflection during the decrabing. Moving the wheel to decrab will ask for flight spoilers to go up and increase drag/reduce lift = sink rate increased. I've tried at 400 feet also but then it sinks if you're not proactive on the throttle. AT is programmed to respond fast to wind gust only, PFC and LAM will help you for pitch, not for speed. In both cases a small application of power smoothen the thing.
My best technique so far, scary for people in the back (I imagine because I'm only flying the box) is to kick the rudder at 20 or so. By the time you ve finished compensating in roll with wheel the speedbrake will be already out and at least one of the mains on ground.
One thing to know about the box and wet runway. We can tune the water depth for the airline it is part of subjective evaluation of the box. So it is different from one box to an other if not in the same company. You might find it easier on one box and terribly hard on the other. Regulation states 3mm or less for water (meaning 1,2 or 2.99 are acceptable values).
Happy landings.
My best technique so far, scary for people in the back (I imagine because I'm only flying the box) is to kick the rudder at 20 or so. By the time you ve finished compensating in roll with wheel the speedbrake will be already out and at least one of the mains on ground.
One thing to know about the box and wet runway. We can tune the water depth for the airline it is part of subjective evaluation of the box. So it is different from one box to an other if not in the same company. You might find it easier on one box and terribly hard on the other. Regulation states 3mm or less for water (meaning 1,2 or 2.99 are acceptable values).
Happy landings.
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The winglow method works better on the B777. Try doing an autoland (if you can, or in the sim) with crosswind and see how George puts her down. Long story short, the A/P, does a fantastic wing-low.
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In strong crosswinds - I prefer a combination of partial decrab (within 5 degs of runway heading ) & one wing low - during the flare.
Airbus does a good presentation explaining the loads on the gear / saturation of flight controls, etc. (around page 6) here
Anybody know of one from Boeing?
Airbus does a good presentation explaining the loads on the gear / saturation of flight controls, etc. (around page 6) here
Anybody know of one from Boeing?
Last edited by rudderrudderrat; 20th Jul 2010 at 18:07.
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In very strong crosswinds above 25kts, a combination of the wing low and decrab method works. Somewhwere in the B777 FCTM, it is recommended that some crab angle be maintained until touchdown on dry runways with very strong crosswinds. However when one straightens the nose after touchdown with the remaining crab the sensation felt is quite unpleasant leading to some dumbos to think that it is a hard or bad landing.
Many years ago a Boeing company test pilot explained to me that because of the long wheel truck, touching down on the rear wheels with a crab followed by a quick straightening of the nose will induce a " twisting " moment which make it seem like a bad landing. I have left the B777 fleet but do remember occasions like these. Pilots who have never physically flown a B777 do not appreciate this characteristic of the undercarriage ith a long wheel truck.
Many years ago a Boeing company test pilot explained to me that because of the long wheel truck, touching down on the rear wheels with a crab followed by a quick straightening of the nose will induce a " twisting " moment which make it seem like a bad landing. I have left the B777 fleet but do remember occasions like these. Pilots who have never physically flown a B777 do not appreciate this characteristic of the undercarriage ith a long wheel truck.
Have done lots of landings in 777 in up to 40kts crosswind (and more in the sim with up to 50kts). Is easiest plane to land ever built!
As per the FCTM, I use the crab all the way to flare. During flare push nose around as per normal techniques and opposite aileron.
Most common error is that guys let the nose drop and aircraft descends onto the runway before fully decrabbed. Yes, you don't want to float past the touchdown zone but a little hold off till straight, then release back pressure, if required, to let it settle on works well. (and of course as others have mentioned, it doesn't matter if it touches down before full decrab, in fact above 31kts Boeing recommend it)
Have tried it also carrying a few extra knots. But even 2-3 kts more than Vref+5 will cause a longer float so even in gusty crosswind is not really required.
Keep it simple - it works.
As per the FCTM, I use the crab all the way to flare. During flare push nose around as per normal techniques and opposite aileron.
Most common error is that guys let the nose drop and aircraft descends onto the runway before fully decrabbed. Yes, you don't want to float past the touchdown zone but a little hold off till straight, then release back pressure, if required, to let it settle on works well. (and of course as others have mentioned, it doesn't matter if it touches down before full decrab, in fact above 31kts Boeing recommend it)
Have tried it also carrying a few extra knots. But even 2-3 kts more than Vref+5 will cause a longer float so even in gusty crosswind is not really required.
Keep it simple - it works.
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Is easiest plane to land ever built!
Wrong! The easiest plane to land is the B747 classic followed by the B744. Flown all 3 types and the t7 is nothing compared to both the B74s.
Wow, surprising that your company allows landing on the T7 above 38kts. Must have empolyed only super pilots! Our outfit design policies for the AVERAGE pilots and do not aloow landing in crosswinds above Boeing demonstrated figures.
Wow, surprising that your company allows landing on the T7 above 38kts. Must have empolyed only super pilots! Our outfit design policies for the AVERAGE pilots and do not aloow landing in crosswinds above Boeing demonstrated figures.
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A former Alteon guy told me how an anal retentive colleague of his failed a pilot who used a combined decrab and wing low landing method in the simulator; apparently it wasn't a very tidy landing but no crash or drift off. This guy mentioned that he just couldn't understand how that colleague could have failed the checkee as the simulator then didn't have the fidelity anywhere close to that of an actual aircraft.
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From Mr Boeings B777 Flight Crew Training Manual
Landing Crosswind guidance
Dry 45 knots, Wet 40 Knots
Ref Page 6.37
T/O Cross wind guidance
Dry/Wet 40 Knots (gets a bit complex at varying weights and MACs)
Ref page 3.12
It also states that these figures are provided for individual airlines to establish
THEIR OWN CROSSWIND LIMITS
Landing Crosswind guidance
Dry 45 knots, Wet 40 Knots
Ref Page 6.37
T/O Cross wind guidance
Dry/Wet 40 Knots (gets a bit complex at varying weights and MACs)
Ref page 3.12
It also states that these figures are provided for individual airlines to establish
THEIR OWN CROSSWIND LIMITS
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Flew the triple for some 8 years, had many wonderful crosswind landings decrabbing during the flare at close to maximum allowable crosswinds. Always nice smooth touchdowns; in the sim, had the instructors crank up the crosswinds to 55 kts.........no problem! I was beginning to think that the B777 IS REALLY A WONDER ( or was I a true boy wonder?! ) until one hot, humid and gusty day ( a typhoon wasn't far away ) at MNL. A bumpy ride with crosswinds about 28 kts.....well a piece of cake I thought with my previous impeccable record of tackling crosswinds more than that. Down to a flare at 30 feet RA and a cool left rudder pressure and right aileron input to align with the runway. In a split second the wings went wiggy waggy and we crunched onto the runway in a most awkward fashion. It really felt terrible and both of us at the pointy end really thought we had a collapsed gear! A call from the cabin indicated some O2 masks dropped. Drat, we really feared the worse. Never had a lousy landing on the triple before.
Seriously we asked tower if we still had the undercarriage intact; not to worry, all was fine. We wrote in a suspected hard landing in the tech log, the maintenance guys did their hard landing inspection. Nothing amiss. The maintenance control guys pulled out the QAR data......no side loads beyond limits and maximum vertical G was 1.51. What a relief but it really felt like such a lousy landing!
Over the next few times with quite a bit of crosswind I was very cautious and wary but most of the subsequent landings turned out great. Then one lousy afternoon in CJU a similar thing happened but not as bad as the one in MNL. Then I never had any more of such crunchers again. I am no ace but I still cannot figure why. Nobody else could enligthen me since.
Seriously we asked tower if we still had the undercarriage intact; not to worry, all was fine. We wrote in a suspected hard landing in the tech log, the maintenance guys did their hard landing inspection. Nothing amiss. The maintenance control guys pulled out the QAR data......no side loads beyond limits and maximum vertical G was 1.51. What a relief but it really felt like such a lousy landing!
Over the next few times with quite a bit of crosswind I was very cautious and wary but most of the subsequent landings turned out great. Then one lousy afternoon in CJU a similar thing happened but not as bad as the one in MNL. Then I never had any more of such crunchers again. I am no ace but I still cannot figure why. Nobody else could enligthen me since.
In a split second the wings went wiggy waggy and we crunched onto the runway in a most awkward fashion.
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I do not remember my aileron inputs that clearly during the first incident in MNL. However I do not normally induce PIOs or make any rapid alternating roll inputs. Having said that, I too suspected that the QAR probably might not have all data on the aileron/spoiler movements when the wings went wiggy waggy in the turbulent crosswinds. I did consider this to be the cause of the cruncher.
The FOQA guys vaguely told me something about the " gear approach " angle being increased suddenly. I did enquire if there were any rapid alternating rudder or aileron inputs indicated but they indicated in the negative. Hence I could not definitively pin point the actual dynamics which led to the cruncher.
Well I am retired now and do not really remember much about the full verbal report by the FOQA guys who had great difficulty articulating the " secret findings " in English ( English was not their first language ).
I have a better recollection of the second cruncher; the aileron inputs and rudder pressure were fairly gentle as far as I remember. As it wasn't that " disastrous" I did not file in any report, so no QAR or FOQA info.
I have come to realise that as always.........." on a one or two lousy day, anything can happen " is an axiom lurking somewhere out there. Bravo and good luck to all the aces, but the 2 crunchers proved a sky deity I ain't!
The FOQA guys vaguely told me something about the " gear approach " angle being increased suddenly. I did enquire if there were any rapid alternating rudder or aileron inputs indicated but they indicated in the negative. Hence I could not definitively pin point the actual dynamics which led to the cruncher.
Well I am retired now and do not really remember much about the full verbal report by the FOQA guys who had great difficulty articulating the " secret findings " in English ( English was not their first language ).
I have a better recollection of the second cruncher; the aileron inputs and rudder pressure were fairly gentle as far as I remember. As it wasn't that " disastrous" I did not file in any report, so no QAR or FOQA info.
I have come to realise that as always.........." on a one or two lousy day, anything can happen " is an axiom lurking somewhere out there. Bravo and good luck to all the aces, but the 2 crunchers proved a sky deity I ain't!
Last edited by woodyspooney; 23rd Jul 2010 at 05:17.
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Yeah, I'm still here, and still trying to work out how to consistantly do a good landing in the B777. The B777 is now my "high time" aircraft, and I'm still trying all of the good advice from fellow Prooners, Boeing, colleagues, and Boeing.
I can honestly say that I have never done a "bad" landing on the B777, but the "good" ones are few and far between. The majority are the usual shake shake shake as the main gear bogies touch down (impact?). At least I've worked out how to fly the nose-wheel on instead of trying to hold it off in a fruitless endeavour to soften it's impact
My personal theory is that the triple bogey main gear is very intolerant of ANY residual drift, no matter how small. Not experienced on other single and double bogey aircraft. On numerous occasions I've had the aircraft set up for what would be a "greaser" on any other aircraft, only to result in the B777 shake shake shake as the main gear bogies touch down.
My last landing was a very good one (the 1% probability), methinks I should retire now whilst the going is good. I'm due to commit aviation again tonight, I know already what the landing will be like (the 99% probability).
Ah well, practice makes perfect.
I can honestly say that I have never done a "bad" landing on the B777, but the "good" ones are few and far between. The majority are the usual shake shake shake as the main gear bogies touch down (impact?). At least I've worked out how to fly the nose-wheel on instead of trying to hold it off in a fruitless endeavour to soften it's impact
My personal theory is that the triple bogey main gear is very intolerant of ANY residual drift, no matter how small. Not experienced on other single and double bogey aircraft. On numerous occasions I've had the aircraft set up for what would be a "greaser" on any other aircraft, only to result in the B777 shake shake shake as the main gear bogies touch down.
My last landing was a very good one (the 1% probability), methinks I should retire now whilst the going is good. I'm due to commit aviation again tonight, I know already what the landing will be like (the 99% probability).
Ah well, practice makes perfect.