B777 wind limits
Hello All. The B777 x-wind limit is 38kts and the autoland limits 25 head,25 X and 15 tail(when the weather requires LWMO). Now what about gusts. Lets say landing on 36,weather requires LWMO and autoland. Wind is 090/20 G 35?
What about a cavok day landing on 36 with 090/32G42? Any ideas? Cheers. |
You continue the approach. Shortly before touchdown, you ask for and get a live windcheck now!, not a recent one including gusts. Any puff of air over your limit, you go-around. That wind actually blowing at that instant is the one you use. An instantaneous wind does not gust. Hey presto, it's magic- it's usually within your limits!
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Boeing aircraft usually have a demonstrated crosswind limit. Most companies also us this demonstrated value as a limit.
I would also suggest that maybe that airport should build another runway in the east/west direction. Landing with a 38 knot cross wind would not be my cup of tea. Maybe the find another airport. |
The B777s I fly have a 40 kt crosswind limit ....................
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Wind at Kinshasa airport...
A light note here...
xxx Kinshasa airport, the 1970s... Back then was "Zaire" (ex-Belgian Congo) Every time we landed, the wind was "two-five-zero degrees eight knots"...! A week later, still 250º/08... Six month later, same story... As we stepped-off the plane, was more like a stiff wind from due South at 20...¿?¿?¿? xxx One day, we are at the bar, Hotel Memling... Many pilots there... I see some Sabena guys, go shake hands with them... bang the mugs with "Simba" beer... Hey, guys, you are experts here, "why in hell is the wind 250º/08...?" xxx A veteran captain told me "you know, their little training booklet gives an example of wind 250 at 8 knots... so they studied that for their test as controller, they memorized it, and that is what you will always get as wind in Kinshasa, for takeoff or for landing"... xxx :* Happy contrails |
Caution when using wind readouts, they are not as accurate as we might believe.
See the very informative report Safety aspects of aircraft operations in crosswind. Paraphrased from the text – “… there is a reasonable probability, that while wind reports to the pilot do indicate that crosswind is not exceeding 15 Kt, in reality the actual crosswind encountered during the landing phase can deviate 10 Kt or even more from the reported wind. For even higher reported crosswinds, deviations may increase accordingly.” (page 15/16) In addition, be aware of gusts and particularly wet / contaminated conditions. |
My B777 flying manual lets me land in a 40kt crosswind too. IMHO the 777 is the most capable big jet transport in those conditions. Interestingly, the automatic approach crosswind limit of 25kts only applies in Cat 2 or 3 conditions. You could in theory let the automatics cope with the tricky crosswind in Cat 1 or better. I don't know if anyone has tried it........
What to do if the wind is gusting around the limit ? If it's unsafe, or the gust hits you in the flare, or you simply don't like it, go round. As long as you get into TOGA mode before the wheels touch, the aircraft will fly you out of trouble, even if you make a momentary touchdown during the go-round. In the Northern hemisphere a crosswind from the right will always be more of a problem in a gust. |
You could in theory let the automatics cope with the tricky crosswind in Cat 1 or better. I don't know if anyone has tried it........ |
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