Saturday, November 17, 2012

Changing Speeds

Even a simple flight can present challenges.  Now they're fun, but I remember being a student and thinking that challenges were, well, challenging!

Friday's challenges actually started on Wednesday with the arrival of an AN-124 at KIDA.  (My friend @Captpretentious, who is based there, took the pictures, and you can see more on his twitter feed.)  Yes, that's a fully-loaded semi driving away from the airplane.

I would really have loved to pop up to IDA and see such a magnificent machine, but other obligations kept me home on Thursday, and they left before my arrival Friday.  Good thing, because I parked at about the fourth bogey of the right main truck.

But I didn't miss it.  You see, runway 20 at KIDA is 150 feet wide, but the Antonov's wingspan is 240 feet.  On departure, it blew a lot of potential FOD onto the runways and taxiways, and IDA's crews were madly scrambling to sweep it up.  This closed the parallel taxiway, so airplanes landing 20 had to back taxi to get to the ramp.


So here I am coming from the South and lined up for left downwind to 20.  A SkyWest RJ is coming from the East and set up for a left base to 20.  We're both 9 miles from the airfield but they're a lot faster, so no worries.  Besides, I have them in sight.

No worries, right?  Yeah, right.

I can't land behind SkyWest because of the debris from the Antonov's departure, so I'm supposed to enter left downwind for runway 17, which leaves me with a long taxi, but it's better than waiting for the RJ to backtaxi.

Right?  Yeah, right.

The RJ misjudged the approach and went around.  That's a good thing!  Here's what it looked like on flightaware:

But it left me in a bind.  I offered to switch to right traffic for 17, keeping me away from the RJ, but the tower had me continue on left downwind for 20.

Now I was flying away from the airport, so I did something I don't see enough pilots do: I slowed down.  Power back until I'm below flap-extension speed, add a touch of flaps, then power back up to stay level.  Just like Tom Carroll taught me in 1983.

The SkyWest RJ completed its lazy turn, me watching carefully -- they'd already misjudged one turn that afternoon -- and as they passed to my left I turned base behind them.

And then I sped up, to get back to the airport.

That did not solve all of my problems.  The RJ was approaching 20, and I was approaching 17, and the two approach paths cross.  The RJ would be long gone by the time I crossed its path, but the wake turbulence would remain.  (Someday I'll tell the story about me in the King Air and the Dash 8 and the 737 on Boise's parallel runways...)

Avoiding the wake meant staying high, but runway 17 is shorter and has had more than its share of overruns.  Basically I have to thread a needle as narrow as an early helicopter's height-velocity envelope: I had to be high at one threshold and low at the other. So, I slowed down to short-field landing speed.

And I'm in this pickle because of the Antonov that left 3 hours before!

Slow down!  Speed up!  Slow down!  Make up your mind!

After an unusual smooth landing I taxied across the field and went about my business in town.   That's a 2.5 mile walk away.

I did not change speed.




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