Wednesday, 15 August 2007 05:50
Dear Captain Lim,
Thanks for taking the time to run one of the best sites on the net!!!
My question is about Adam Air Flight 574. I had seen in various media reports that "The plane ran into crosswinds of more than 130 km/h" or the plane "battled crosswinds of more than 130 km/h"
I am wondering what the approximate crosswind limits are for jets at cruise? I think I saw that on the Boeing site that the 737 crosswind limits are around 30 knots for landing and takeoff?
But I am wondering at cruise with jets flying in and out of the jet stream all day, all over the world, would 130 knots be a common encounter?
Thanks for your time.
One of your loyal fans,
During the cruise, crosswinds are not a major problem to jet liners. It is during the landing or takeoff when they become critical. Hence the technical specifications of all jet liners come up with crosswind limitations (some manufacturers prefer to call them "crosswind guidelines" or "demonstrated crosswind")
For the Boeing 737-400, the maximum crosswind limitation is 29 knots for take off and landing.
On a Boeing 777, it is more specific and the limitations for take off and landing are different. For instance, the guidelines for maximum crosswind on a dry runway during landing is 45 knots (52 mph), wet - 40 knots, with standing water or slush - 20 knots, on snow (no melting) - 35 knots or icy surface (no melting) - 17 knots. The more slippery the runway, the lower the crosswind.
Regarding the Adam Air Flight 574 (see here), I believe, the crosswind has probably nothing to do with the accident because it did not happen during the landing. In fact, it was reported that the Boeing 737 crashed into the sea.The reported crosswind of 130 km/h (80 mph) was encountered by the ill-fated flight over the Makassar Straits.
During the cruise, there are no limits on the crosswinds. Wind speeds of 130 knots are very common in jet streams. Pilots take advantage of such winds by flying along them and not against them. If a plane has to fly across the jet stream, it then becomes a crosswind. If the pilot does not take the drift into consideration, the plane may be blown off course.
A plane with a good navigational aid would correct for the crosswind. Flying across a jet stream may be rather turbulent because of the varying speeds as the highest velocity is at its core.