Why were airplanes flying the wrong way over LA today?

October 18, 2012 9:48 PM

Why were airplanes flying the wrong way over LA today?

Every time I've seen planes take off from or land at LAX, and when I've flown in and out of there myself (and I've lived here many years), they would approach from the east and take off toward the west. Planes arriving from the west would fly over LA, bank over downtown, and land going east-to-west.

Today, I was driving north on the 405 and was shocked to see planes taking off toward the east, and I could see the lights of low-flying planes over the ocean, approaching to land from the west.

So why was LAX traffic reversed today?

It was mid-morning that I first noticed it, and also later in the afternoon. There were some low clouds in the morning, but no rain, and no wind to speak of. Nor Space Shuttles.

I found this link but it doesn't explain much except to say that it is indeed rare.

posted by univac to travel & transportation around Los Angeles, CA (9 answers total)

I don't know what the weather conditions in LA were exactly, but this happens sometimes in San Diego as well. The reasons typically have to do with weather - either low visibility or wind direction going the opposite of the prevailing (like during a Santa Ana). Normally, the wind in LA will come from the west, so planes take off/land in that direction. Plus, there's less noise concern since planes are then taking off over the ocean.

Here's discussion page with a similar question. Someone mentions in there that winds may be higher slightly aloft than they are on the ground. I know things were slightly unsettled down here today and we had pretty decent wind around noon.

Here's something on reversed operations at San Diego.
posted by LionIndex at 10:07 PM on October 18, 2012

This is actually not unusual. It's the same in nearby Orange County. So-called "Santa Ana" wind conditions dictate taking off the other direction in order to head into the wind and get sufficient lift for take off.
posted by Dansaman at 10:12 PM on October 18, 2012

Given the weather today, I'd think the wind would be more due to a low pressure system or something (it was mostly overcast, windy, with a chance of precipitation in SD today and LA gets our weather before we do, usually). Today was definitely not a Santa Ana.
posted by LionIndex at 10:21 PM on October 18, 2012

It's better for planes to take off and land against the wind. There's more airspeed across the wings, and hence lift, for a given groundspeed.
posted by Rich Smorgasbord at 10:42 PM on October 18, 2012

I'll place buckets of good money that the answer is simply "the wind". You land into the wind as much as possible, simple as that. Landing an aircraft with the wind at your back is a really silly idea (just one more reason to laugh at Snakes on a Plane and that final landing sequence)...
posted by ewan at 3:22 AM on October 19, 2012

This link has the winds for the past 24 hours at LAX.

To read it: after the term KLAX, the next item is the time in UTC (think London) followed by the wind heading and speed. For example, 12010G16 means winds out of 120 degrees (southeast) at 10 knots with gusts to 16 knots.

So yeah, it was the wind direction. It's safer to take off and land into the wind because the plane travels over much less ground that way (operating the other direction means possibly running out of runway) and is moving more slowly over the ground for a given airspeed.
posted by exogenous at 4:34 AM on October 19, 2012 [2 favorites]

There's also a graph of wind speed and direction at the bottom of this page. It was out of the east or southeast until about 3 PM yesterday afternoon, at which point it shifted to the west.
posted by Johnny Assay at 5:25 AM on October 19, 2012 [1 favorite]

The other complicating factor could be that some other nearby airport needed to change its pattern, which caused LAX to have to change its own pattern to stay out of the way.
posted by gjc at 7:41 AM on October 19, 2012

Wind, got it. And it's different at higher altitudes. Thanks for satisfying my curiosity everyone!
posted by univac at 8:32 AM on October 19, 2012