About 30 years ago while I was working in Oklahoma City at PWA, I had a
doctor working on his IFR rating. It was a clear night, winds were calm on
the surface, dead calm. Winds aloft reports and forecasts were normal at
20-30 knots.
We took off and at about 200 feet hit some very heavy chop that lasted about
5 seconds. Then it smoothed out.
We did a VOR nav problem up to Kingfisher to hold, then an ADF to Norman for
an ADF approach.
We did some TAS and wind calculations just to fill in the time. The winds
we calculated [we didn't have DME and this was well before GPS] was out of
the south at over 100 knots. We were at 4-5000 feet [3000 AGL].
A Cessna 150 had called in up north, enroute to OKC, approach asked his
speed. They were tracking him at less than 20 knots GS.
A Saberliner called in, approach asked if they had TAS computer and knew the
actual wind. They reported 190 at 130 knots on descent through 9,000 feet
and 120 knots at 3000 on initial.
Sometimes the jet stream dips down. When we finally landed, winds were
still dead calm at PWA.
I also experience a downburst at PWA, while checking out a Texas
International Airlines captain to rent an Archer to take his grandkids for a
ride. On our first pattern on 17R we saw a dark cloud over the small lake
just sw of the airport. The next time around we looked up and saw a black
wall in front of us and began a steep turn to avoid it, but it was too late.
We swallowed the bank and went on instruments. This began at about 500-600
feet and we came out of the turn with a very clear view of the tree leaves.
We declared an emergency and advise the tower of what was happening. They
said the wind was calm, but we could land on any runway of our choice. We
landed on 17 L and taxied into Catlin and had it in the hanger in just a few
minutes. The down burst drifted north over the parallel runways for 10-15
minutes. You could see the winds was blowing directly away from the center
of the down draft. The tower reported a gust of over 45 knots.
wrote in message
...
| On Dec 23, 12:19 pm, "BT" wrote:
| you checked all the local airport surface winds.. but did you check
winds
| aloft? or look for Airmets for Turbulence?
| BT
|
| wrote in message
|
|
...
|
| I planned to give some night flight rides to friends and family
| visiting this weekend. Winds during the day were steady at 8 or so at
| MGW and ACG. I called the Connellsville (VVS) AWOS and it reported
| winds calm after dark. So it looked like a good night to take a
| pleasant joy ride.
|
| Temps were hovering around 50 so no preheat required. The engine
| started up immediately and I maintained a 1000-1100 RPM idle for a
| while to get the engine up to operating temps.
|
| After a suitable warm-up, I briefed my two passengers and rolled onto
| 23.
|
| The ground roll felt fine and initial take off was normal -- but once
| we hit 150' AGL the pleasant flight turned into a battle to stay
| upright.
|
| The topography near VVS is somewhat complicated with low level series
| of hills known as the Pittsburgh plateau to the west and the
| westernmost ridge of the Alleghenies immediately to the east (you can
| hit that ridge if you don't turn soon enough after taking off from
| 14). The mountains run slightly west of south in a line towards West
| Virginia.
|
| This evening the rather light winds were being reported as variable
| (all over, actually) by the AWOS. But what was really happening was
| that a very strong wind was blowing from the south very close to the
| ridge altitude (approximately 2500' MSL), and then rolling off the
| ridge line. So what VVS AWOS was sensing and reporting were the
| swirling eddie undercurrents (thus the generally west winds). The A36
| is usually a very stable airplane, but in these conditions it was
| taking full control deflection to remain upright. I apologized to the
| passengers and told them we were heading back.
|
| I continued climbing at 110 KIAS until about 2500' MSL (only about
| 1300' AGL) where it seemed a bit less turbulent. Once established
| level I began a shallow 270 degree turn with the initial turn to the
| west to keep us away from the direct lee of the ridge. While still
| turbulent, it was less violent than what we had experienced on climb
| out.
|
| I considered landing on 14, but it is a shorter runway with no PAPI. I
| decided I would take my chances on 5, given it is the longest runway
| at VVS and that surface winds were variable, so there would be no
| certainty of headwind or tailwind. I listened to the AWOS and the wind
| direction was unpredictable, yet velocity never exceed 8 knots.
|
| I trimmed the airplane for 85, but airspeed fluctuated between 80 and
| 100 on extended final. I was actually approaching runway 5 at about a
| 40 degree approach angle to stay as far from the ridge as long as
| possible.
|
| Once the runway environment was in sight and established, the PAPI
| indicated high on the glideslope. But I wanted to come in somewhat
| steep and fast to avoid ground turbulence. I decided to add flaps to
| help steepen and slow the approach.
|
| This worked out, and the steep descent at 80 KIAS brought me just shy
| of the aiming point. I reduced power and flared flat. A final kick of
| the rudder and we were straight and centerline. We touched down very
| gently and maintained centerline on rollout, with minimal braking
| required.
|
| This night was nearly identical to my experience in the V a few months
| ago -- wild, full-deflection turbulence with near smooth as glass
| touchdown. I think the main issue when the wind is blowing from
| between 060 and 190 is the strong sheer above the airport -- the
| stronger the wind, the higher the eddy area. In really strong winds
| (30 Kts), the AWOS is completely unreliable and the eddy currents
| 200-1000 AGL are nearly unflyable.
|
| If I was going someplace, I would have turned west and climbed to at
| least 8000 before picking up any heading between 030 and 180.
|
| I only logged 0.5 tonight but it was quite a bit packed into that .5!
|
| Dan
|
http://trainingforcfi.blogspot.com/
|
| Always do.
|
| If you've been flying long enough you soon learn to winnow out more
| reliable forecast data from more speculative. Winds aloft and AIRMETS
| often lean towards the latter.
|
| If you don't fly anytime there's an AIRMET, I feel sorry for you if
| you're a pilot n the Northeast..
|
| Dan