Sunday, September 2, 2012

Be Careful What You Wish For

Summer in southeast Idaho means gentle weather.  Take that with a grain of salt, or even a salt tablet or two.  Gentle means no IFR, but with field elevations at or above 4,500MSL and temperatures over 90F/32C, the density altitude is off the scale.  But we also have long runways. Take a look at the New York sectional with its low elevations and you'll see a large number of runways shorter than 3,000ft; we have few, if any.

There were no long cross-countries this summer, mostly because my twins are learning to drive and we made a bunch of road trips to give them practice.

So I had been wishing for a more challenging flight.  Be careful what you wish for.

You might remember that my university has two campuses, and when I teach at the other campus I like to fly there.  The state reimburses us for private aircraft use as if it were a car, so the current auto rate is muliplied by the "book" mileage.  This is less than the cost of flying but it helps quite a bit.

The big problem with flying is that there is no reliable method of ground transportation from the airport (KIDA) to campus.  I have discovered an elegant work-around to this problem, however: I walk the 2.5 miles.  A good chunk of the walk follows the Snake River, so it's pretty; and, given my health history, exercise is important.

My first KIDA class was Friday.  After weeks of clear and dry weather, though, our monsoon had arrived.  A monsoon in the desert?  Isn't the Indian Monsoon a source of massive amounts of water?  Yes, but a monsoon is just a seasonal shift of prevailing winds, so this is a dry monsoon.  But a monsoon nevertheless.

Change of plans: this year the monsoon is wet, or at least wetter, and there was a 30% chance of thunderstorms in the afternoon.

Aha!  This would be my more challenging flight!  Scattered storms like that require some diversion, but there would be lots of room and lots of gas to divert.  Fun!

The flight up was very smooth and quick.  Too quick.  The winds aloft were more southerly than forecast, which is always a bad sign in the Northern hemisphere: that's warmer air, capable of carrying more moisture.  As I walked to campus I couldn't help but notice some buildups to the East, over the mountains.  I tweeted "Hoping builups E of  due to orographic lift and desert will remain clear for trip home. Lots of moisture & instability ."

One of National Weather Service tweeps replied "Don't count on it. :-)".

I ate lunch, walked to campus, taught my course, did a get-to-know-you with the students there, and started to walk back to the airport.  The view was a bit unsettling:

This was headed south along the river, looking down the trailing edge of a line of thunderstorms.  There was one clap of lightning.

One of my mottoes is "Sometimes, you just have to fly toward the blue sky," and there was blue sky to the West.  So I was not worried, although the prospect of a challenging flight did put a little spring into my step for the final mile or so.

Well, let me amend that: I wasn't worried about the flight.  I was worried about my tablet-computer-which-must-not-be-named, or TCWMNBN.  You know, the one with all the charts.  The sky started to spit a little rain...

...but I was prepared, dug out my raincoat, and kept going with the TCWMNBN under the coat, happy and dry.

But now I was getting over heated.  The rain stopped, and I took off the raincoat.  But then it started up again.  Grr...

It was dry when I got to the airport, so I did a quick online standard briefing and walked out to the airplane.  KIDA has airline service so I suppose that I should have had an escort, but there was nobody from the FBO around and weatherwise it was time to go.  Nobody challenged me, I did the walk-around, started up, and launched.

I held Vy (best rate-of-climb airspeed) to 500' AGL in case of wind shear, and planned to slow to Vx (and no slower) if there was.  But there was none.

Despite my NWS friend's dire prognostications, I was right.  The buildups stayed east, there was blue sky to the west, and I flew the seam between them with few bumps and just a couple of raindrops: VFR with lots of visibility.  I did take the precaution of keeping the TCWMNBN under my leg, in case of sudden bumps.  But there were none.  There was a rain shaft to the west, which Center warned me about, but I was able to reply with a laconic "Yeah, we've been watching it, thanks."

Things looked good for a straight-in approach.  I did not fly through the localizer this time, because I was paying attention [see the previous post].  I kept my speed up, because this was costing me money.

Inside the marker, Ken, in the tower, came on to say that the wind was shifting, and was now 350 at 4.  An acceptable tailwind.  Gusting to 15.  Oops.

Many years ago I had an incident with Ken that taught me a lesson.  I was on left downwind to 21, and Ken came on to say that there was a thunderstorm in progress overhead.  It was a western thunderstorm, with a high cloud base, and I decided that Ken didn't know what he was talking about.  Mistake! There was a 2000+ fpm downdraft on base, and I struggled to keep from shining the bottom of the airplane on the potato plants below.  This time I listened.

"Tower, change of plans, we'd like to enter left downwind for 3."

"Approved as requested.  If you like, long landing approved." Remember, we have long runways, and it's a long way from the threshold of 3 to the FBO.  I was below pattern altitude, closer to circling minimums.

"That sounds good to me," I said, then added, "Or, as you guys would say, approved as requested."

We had a good laugh, I landed, and called it a day.


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