The weather in Anchorage.
I’m preparing to take a trip to Anchorage, Alaska next week for a job interview. If all goes well, I’ll be moving up there for the summer, flying tourists around glaciers and delivering 50-gallon drums of dog food to sled dog camps via long line.
In trying to get a handle on what to pack for my 3-day trip, I’ve been monitoring the weather in Anchorage, using the National Weather Service Web site. Here’s what I read this morning at 6 AM my time (4 AM Anchorage time):
Remainder Of Tonight…Mostly cloudy with a few sprinkles. Lows in the 30s. Southeast wind 40 to 55 mph along turnagain arm and the higher elevations with occasional gusts up to 70 mph. Elsewhere southeast wind 10 to 25 mph with localized gusts to 40 mph.
Okay, I added the emphasis. The NWS evidently doesn’t think 70 mph gusts of wind is unusual, since the forecast didn’t include a weather advisory. I know there would have been one in the Wickenburg forecast page if the winds were expected to reach 70.
My Experience with Wind
I flew tours at the Grand Canyon in 2004. In the spring, the wind was howling, occasionally reaching 50 mph or more at the airport. Because we flew Bell 206L (Long Rangers), which had a two-bladed rotor system that didn’t do well in high turbulence, we’d shut down if the wind got that bad. But the experience of flying at the Grand Canyon in spring and having to deal with all of that wind made me a lot more comfortable with high winds than the pilots who haven’t had to deal with it. That’s why I always recommend flying at the Grand Canyon as a first “real” job after flight school and duty as a CFI. Lots of good experience there.
Still, I don’t expect to fly in Alaska with 70 mph gusts. (I hope my potential employer doesn’t expect me to, either.)
Yesterday, I did a flight to Scottsdale with a client. Although the winds were relatively calm when we flew down there — variable at 4 mph according to the Scottsdale ATIS recording — they were forecast with gusts to 30 mph for that afternoon. Sure enough, when we left the area at about 5:15 PM, the wind was 16 mph gusting to 23. That’s certainly not bad enough to keep me on the ground, put I did have to give the pedals a workout as I lifted off the ramp. I also had to put in a lot of directional correction against the wind when I took off, just to prevent it from blowing us over the runway (which would have gotten me in hot water with the Tower there).
What’s Wrong with Wind?
There are two things that can make high wind especially bothersome for helicopter pilots:
- When flying in mountainous (or even hilly) terrain, the wind coming over those mountains (or hills) makes the air turbulent. Here’s how I describe it to passengers. Imagine a stream with rocks in it. As the water flows downstream, it sets up eddies and weird water flows around the rocks. The water has to go up or around the rocks in its path. It then goes down or rushes in from the sides on the downstream sides of the rocks. Can you imagine it? Now imagine the mountains or the hills as those rocks and the wind as the water. The helicopter is like a little boat bobbing around in that water. That’s the turbulence you feel when you’re flying relatively close to the ground on a windy day near rough terrain.
- A gust spread — that’s the difference in airspeed between the steady wind and the gusting wind — sets up what probably meets the definition of wind shear. Most pilots know that a wind shear is created where the wind suddenly shifts direction or speed. A gust changes the speed, right? The result, therefore, is the same kind of turbulence you’d feel in a wind shear. The bigger the gust spread, the bigger the shear, the greater the turbulence.
Not all helicopters handle turbulence the same way. Generally speaking, a fully articulated rotor system is better for handing turbulence than a semi-articulated system. But no matter what you’re flying, you’re going to feel those bumps. So will your passengers. Fortunately, they’re likely to get sick before the pilot does.
When I flew at the Grand Canyon, the wind was so bad a few times that I started feeling sick. Some of my passengers, as you can imagine, were making full use of the plentiful barf bags we had on board.
Will Alaska Be Worse?
Right now, I’m left to wonder whether Alaska will be more of a challenge due to wind than the Grand Canyon was. Although I’d prefer calm winds — who wouldn’t? — I’m up for the wind challenge, if I have to face it.
I just hope it’s not 70 mph.
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All I can say about 70mph winds is -GULP-! I didn’t know it was that windy up there either. I don’t think I’ll ever find myself working in Alaska but the Ditch is a good possibility. One of my former CFI’s is working there in EC130s and loves it. I liked your explanation using the stream to illustrate mountain winds. Fortunately I am getting some great exposure to that here in Northern Cal. What will you hopefully be flying in Alaska and for whom?
I thought I knew about wind when teaching Japanese in Maui on 300Cs. I also had the chance to sample the Santa Ana winds in Southern California before that. Then I landed a job on Umnak in the Aleutian Islands herding cattle with Robbies. There is a narrow window between August and November when visibility is clear but winds can pick up up to 70mph, and it is within this span that we have to do most of our work before winter sets in. Spooling up and down can be a problem. But the little R22 has proven itself to be a gutsy machine under these conditions. I can imagine working the thermals of the Grand Canyon can be tricky.
Maybe I can learn how to fly there someday too.
The only place in the canyon where we had to “work” the winds was on the east side, near Kibbey Butte. We’d be flying at 7500 feet as we approached Point Imperial, where we began a climb. We had a get a minimum of 8200 feet of elevation to get over the North Rim and continue westbound. The winds usually hit Kibbey in such a way that there was an updraft. We called it the Kibbey Elevator. When the elevator was working, you could count on it to help you climb. But when the wind wasn’t blowing quite right, the elevator was broken and you’d have to circle in a relatively small space, to get the elevation you needed to continue on your way. I only had to circle there twice (once each on two flights) but another pilot had to circle twice on a single flight. Normally, when the winds got bad on the east side of the canyon, we’d only do tours on the west side.
Other than that, there were just updrafts and downdrafts where you didn’t want or need them. With the airplanes flying just 500 feet over our heads, an updraft was something to watch out for. I got into an 800 fpm updraft that shot me up into airplane territory once; had to drop the collective almost to the floor to descend out of there.
Robinsons have Bells beat when it comes to tail rotor authority in heavy winds. Never had any serious LTE problems in my R22 or my R44, but I sure don’t like starting up or shutting down when the wind is gusty.