Calm wind = perfect day to fly?

Reflection on yesterday

 

Yesterday it hurt to watch planes land while I was patiently waiting my turn at the hold short line.  It was a reminder of why it is good not to have an office with a window when you are the chief flight instructor. 

 

It was a day with light and variable or calm winds all day long.  It seemed like a perfect day to fly with nothing to be concerned about on landing.  After all, there was no crosswind or gust, so no problem, right?  Wrong.

 

In general calm surface winds cause pilots to come in high and fast.  The pilot normally has a headwind component on final, now that is gone, and the groundspeed is higher resulting in a diminished angle of descent.  As the pilot flares halfway down the runway and gets impatient as the plane continues to float, the pilot may attempt what is impossible – try to make the plane land while it is still well above stall speed.  The plane cannot be forced to land and will porpoise – a very dangerous situation that requires immediate corrective action.  See details on page 8-31 in the Airplane Flying Handbook http://www.faa.gov/library/manuals/aircraft/airplane_handbook/media/faa-h-8083-3a-4of7.pdf

 

Pilots came in high and fast all day long yesterday.  The diminished angle of descent tempted pilots into pitching down "diving for the runway".  That may have gotten them to their target spot, but now excess speed caused extremely long floats.  In late afternoon it became more of a problem as the winds aloft changed before the surface winds.  The surface winds were still in favor of 33R, but the winds aloft had changed.  The surface winds eventually changed nearly 180 degrees at 2:45pm – see METAR history below. 

 

There was a warning of this immanent change – for a long period prior to the surface wind change I noticed a significant tailwind component on final resulting in an even lower angle of descent to the runway with normal pitch/power.  I saw a lot of "diving for the runway", long floats, and even a little porpoising.  No airplane damage thankfully, but probably damaged pilot egos if there were passengers riding along.

 

So, with calm winds plan on using a lower power setting as you get abeam your touchdown point on downwind, and/or extend your downwind, and/or lower flaps sooner, or GO AROUND AND TRY AGAIN WITH ANY OF THE ABOVE – DON’T PORPOISE!  For fun hang out at the airport when the wind is calm and you can learn a lot, but I’ll try to avoid the show.

 

KMWC 042245Z 11006KT 10SM SCT120 07/M05 A2999

KMWC 042145Z 11007KT 10SM SCT120 08/M04 A3001

KMWC 042045Z 13007KT 10SM BKN110 09/M04 A3003

KMWC 041945Z 11005KT 10SM CLR 11/M03 A3003

KMWC 041845Z 33005KT 10SM CLR 11/M03 A3004

KMWC 041745Z 36003KT 10SM CLR 09/M03 A3006

KMWC 041659Z 31007KT 10SM CLR 09/M04 A3008

KMWC 041545Z 35010KT 10SM CLR 08/M04 A3006

KMWC 041445Z 32007KT 10SM CLR 07/M02 A3006

KMWC 041355Z 32006KT 10SM CLR 04/M03 A3006

KMWC 041245Z 28005KT 10SM CLR 02/M02 A3005

KMWC 041145Z 00000KT 10SM CLR 00

 

 

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