There's a pretty harrowing video making its way around the internet today of a Boeing 777 as it makes an attempt (and fails miserably) at landing. But it's no crash — thanks to an insane crosswind, it literally cannot land.
Pilots deal with this stuff all the time, and they say it's pretty routine. I disagree. It looks terrifying.
"A 777 is on approach to Birmingham airport in a crosswind..." sounds like the beginning to a high school maths problem. That's because it is a high school maths problem! This is an example of "vector addition". The crosswind component would normally force the plane off-course according to an observer on the ground. So to counteract the crosswind vector, the pilots rudder the plane off centre (called "crabbing") and depending on the wind angle, adjust their airspeed so their resulting "ground speed" vector (hopefully) lines up with the runway.
This is hard for two reasons. First, turning a huge jet at the last second, while not over-correcting, while ferrying hundreds of nervous people who all have to go the bathroom very badly, is not an easy task. But there's physics at play, too. If there's enough crosswind, the rudder just isn't powerful enough to sufficiently crab. During testing, the manufacturers also test the maximum crosswind that's safe for the landing gear because of that gnarly last-second twist. Plus, pilots aren't without fear, and if they aren't comfortable then they aren't going to land (see previous note about hundreds of anxious bladders in cabin).
Of course I had to do the maths: This plane must have been on the high end, otherwise I don't think they would have even attempted the landing. According to the internet, which we can trust (right?), the 777 likes to land at about 250-260km/h airspeed. This plane looks like it's pointed about 20 degrees off-centre, too. I calculated the vectors and it tells me that the crosswind is probably exceeding 80km/h. The 777 has a maximum crosswind (according to the internet) of 70km/h. Good choice not to land.
So as it turns out, those pilots must have been feeling pretty damn bold to even attempt the landing in the first place. Scary-arse crosswind indeed. [Thanks, Joe!]
Joe Hanson is the host and writer of PBS Digital Studios' science YouTube series It's OK To Be Smart. You can follow him on Twitter Twitter here. You can also find him on Tumblr here.