Microlighters

Had this experience this morning and boy, this was something very shocking .

Decided to go for a couple of circuits this mornin'. Filled the Challenger with 5Gallons of fuel and pulled out of the hangar. The outside temp was 21 Deg and the wind was light Westernly but swirling between SW and NW and the time was 0730Z. I have 46hours total in my logbook and 10 hours on type.

Did my preflight and strapped in. Just as I was about to start the engine the wind started blowing a wee bit stronger, but not so much that I worried to much though, BUT at that stage I was in doubt if I must take off. And what did my instructor teach me?? When in doubt.... don't fly . But the Challenger have a 20mph crosswind component and this wind was not nearly 20mph.

Started the engine and taxied to holding point and did my checks and looked at the windsock and start taking off. Within less than 30m the Challenger was in the air and climbing like a homesick angel. I turned to the right into the wind and away from the mountain (2-3km on my left) and everything was smooth as butter, although she climbed very faster then normal, but can't say how much for I have no VSI. It felt like the aerie was on a crest of a wave so light was the climb. At 500ft AGL I felt that the air was suddenly very cooler than a few seconds ago. I leveled out on 600ft AGL and start trimming the aerie. The next moment I experienced some turbulent air and the aerie would suddenly rise and then drop again. I have flown in turbulent air before, but the way this turbulence behaved, suddenly didn't look so tame. My hand on the throttle, I reduced the revs to 4900.

The next moment something grabbed the aerie from beneath and shot it straight up into the air for 300ft in what feels like in the wink of an eye Before I could realize what was happenin', I suddenly shot straight up in my seat although I was strapped in securely and my head hit the trim crank in the roof and the next moment the plane toppled over in a dive straight down. Instinctively I closed the throttle and pulled back on the stick, but the aerie kept on diving, by the time I got out of the dive, I've lost 400ft and my airspeed was 100mph . My cellphone that was in my shirt pocket was lying on the floor and the logbook also. The pen that was with it, was gone. All this happened very, very, very bloody quickly. The air was stable again now and the airfield was less than 400m away, but it looked so far and my legs were trembling so much. I was creeping allong to the field and looking for another one of these monsters that attacked me a few seconds ago. BUT, I cant see them and I don't know where they are. The next moment I encounter another quite violent turbulence but not as bad as the big one. I landed as quickly as possible and by now my legs were steady again for I lined the aerie up perfect in the crosswind for the landing.

Now for the questions: Was this just turbulence or was it windsheer?
Did I do correct to close the throttle when I toppled over, or would it be better to use the power to
get out of the dive? Remember even with the throttle closed the speed reached the Vne in the dive.

But I don't know if this was really a close call or just a normal experience, but I know I'm glad that I've survived this so that in future I will not fly this time of the year that time of the day when there is similar conditions.

All you guys with years and years of experience, what would you've done in such a situation or would you stayed on the ground.

I can say with all confidence that this experience did not rattle me so much that I am adruptly stopping my flying now. I will definitely be in the air very soon, but preferably when the conditions are 100% for now.

Safe Flyin'

Well done. Close throttle was good thinking. VNE is not your friend. Always FLY the plane (which you did).

Difficult to judge what it was without knowing the area and what WX was around. I would suggest that it was thermic activity rather than windsheer.. Were there and largish clouds about?

Clear skies, but here in the Western Cape at this time of the year the wind starts blowing by 09h00 in the mornin' and blows strong until 20h00-23h00 when it subsides.

sounds like rotor from over a mountain.
http://www.nationmaster.com/encyclopedia/Rotor-wind
http://www.atsb.gov.au/publications/200 ... lence.aspx

Might be, however, the wind was blowing towards the mountain and not from. When we have Eastern winds over this mountain, we experience rotor activity, but not Western winds. But these unseen activities is really terrifying to say the least.

i've seen wind at altitude blowing the opposite direction the wind on the ground so it might have been that there was wind over the mountain anyway ???? just guessing here. Me no weather expert...

Sounds to me like rotor or mechanical turbulence possible. Can catch one off guard.

Please post a Google photo of the area.

My guess is stable air turbulence (bad) from off-shore. However if the field is inland it is not un-common to experience off shore wave. Ride it and turn 90 degrees into the valley of the wave.

Watch out for whip-stall coming off throttle too fast. This is what might have put you in the 100mph+ bracket.

Glider pilots also talk about clear blue turbulence. Scary stuff... Air moving in different direction (usually up or down).

PS
Around CB's this is common... I been caught in one (albeit a huge CB, - at Idle I was doing 2000+ft min up and 160kts .... Nothing like peeling yourself off the canopy at FL110 after a couple mins when you were last at FL075..... My old man once got "caught" in updraft with instructor in 172 and they got spat out around FL135 after 4min "RIDE".... Instructor had 23'000hrs and said it had only happened 2 times before

Wallaby.
Your airfield?
Graham

kloot piloot wrote:Watch out for whip-stall coming off throttle too fast. This is what might have put you in the 100mph+ bracket.

Kloot, this is a 3-axis, it does not whip stall

As Harlequin said, which airfield?

I had a similar experience in my Challenger in 2005 routing FAFK to Morning Star, then the wind was easterly. One moment I am flying at 1000ft the next free fall loosing 300ft in 2 seconds and suddenly massive bounce back up. Was a result of a standing wave coming over the top of Paardeberg

The fact that it was westerley on the ground doesn't mean it will be westerley upstairs. I have taken off at Saldanha on a SE, climbed to 1000ft and had a NE tailwind and landed back at Morning Star with a SE. This was 2 weeks ago. Through experience I have seen the wind shift up to 130degees clockwise (viewed from the ground) as you go higher due to the Coriolis effect

And if this was the case then the sudden change in direction will result in wind shear, and turbulance.

Thanks for sharing the experience Wallaby. You made a good statement earlier on in your post....When in doubt, don't fly. Although this is not scientific I think that human intuition is a powerful too to rely on. It is also good that you flew the plane and did not try and find the cause of the problem. All in all a great ending and learning experience, albeit a terrifying one.

Wallaby,

Come to think if it, I experienced a similar phenomenon about 2 months ago, in the same area. Was flying from Grootfontein, near FAFK, towards Morning Star, with a slight westerly wind, and just NE of the Durbanville hills (the one's NE of Tygerberg), I suddenly got some quite dramatic lift, shooting upwards with a VSI of at least 500 ft/minute.

I was slightly surprised by this, since, if anthing, I was actually expecting some downdraughts, flying in the lee of the Durbanville hills. Strange. At least in the gyro it wasn't a bad experience, just a bit unexpected only.

Being an ex. Valie, I'm still getting to understand the local wx. here.

There have been a few terms used here that I have never heard of before, and am keen to learn more if these terms are the correct ones, namely: stable air turbulence (bad) from off-shore, off shore wave (a type of standing wave?), and clear blue turbulence (I think the poster means CAT Clear Air Turbulence?)

Do explain more for the sake of us Valies that only know about wirlwinds and thunderstorms!

Morph, this was from Cassie's landing strip North of Eendekuil. You know it all too well.

Had another 1.4hrs from before 6 this mornin' and had a absolute fabulous time in the air. Lovely weather early in the mornin', but yesterday I thought that I needed some more crosswind experience, but nearly saw my arse . Conditions can change a lot from 6 in the mornin' to 10h00.