Twin Otter Mishap Orchid Island 13 April 17
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Location: 5° above the Equator, 75° left of Greenwich
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I was trained by a DHC test pilot, who would not let me fly 40 flap landings, until I really impressed him with my flaps 20 landings. He also trained me in 30 flap takeoffs, but that's a story for a different time...
The Twin Otter is a very sure plane to fly, so one feels pretty confident handling them - occasionally too confident, perhaps...
The Twin Otter is a very sure plane to fly, so one feels pretty confident handling them - occasionally too confident, perhaps...
As for the flap 30 takeoff...I believe there's a crash (on video) in Canada of a failed takeoff in such setting. I've done flap 20 takeoff and it keeps you on your toes, no idea how a flap 30 takeoff would feel.
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It's been a long time, but my recollection of the 30 flap takeoff technique was that of being a trained maneuver, which should not be attempted without the training. The video bears that out. I was briefed exactly what to do, and it worked exactly as briefed. I can see that experimentation would end poorly.
That said, the Twin Otter's short field performance is so excellent with the approved takeoff technique, I can't see a need for 30 flap takeoffs in a practical sense - thus it is, and should be an unapproved maneuver. I think for me, it was just a training exercise (mostly in following a briefing during a challenging operation!).
During my experience with STOL modified Cessnas and other light types, I find that there is often an over eagerness to peel the aircraft off the surface at the first possibility, and then steeply climb away at the slowest airspeed - for zero operational need. High risk, no reward. With GA flying, that foolishness is impossible to regulate. With the Twin Otter, which is nearly always flown in an "operator" environment, it's easier to limit the types of activities. There are distinctly non STOL flying techniques published for the Twin Otter, which are perfectly suitable for most operations.
That said, the Twin Otter's short field performance is so excellent with the approved takeoff technique, I can't see a need for 30 flap takeoffs in a practical sense - thus it is, and should be an unapproved maneuver. I think for me, it was just a training exercise (mostly in following a briefing during a challenging operation!).
During my experience with STOL modified Cessnas and other light types, I find that there is often an over eagerness to peel the aircraft off the surface at the first possibility, and then steeply climb away at the slowest airspeed - for zero operational need. High risk, no reward. With GA flying, that foolishness is impossible to regulate. With the Twin Otter, which is nearly always flown in an "operator" environment, it's easier to limit the types of activities. There are distinctly non STOL flying techniques published for the Twin Otter, which are perfectly suitable for most operations.
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We used to do flap 10 takeoffs, our normal operation didn't need more than that. We did flap 20 takeoffs in training as a demonstration maneuver. It needs to be a very conscious maneuver as you can get in serious problems very easily if you don't know what you're doing. Rotation speed is below Vmca, for starters...
Still, it's a fun thing to do
"Mildly" Eccentric Stardriver
IIRC, Perf C in the UK. That also allows, among other things, the assumption that an engine failure will not occur below 50' agl. I'm way retired, and my Otter days are nearly forty years in the past, so excuse any errors.
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The Twin Otter Series 100, 200 & 300 were approved to the US Civil Air Regulations Part 3, at amendment 8, which allowed Vr to be below VMCA. Certain later operating rules applicable to some operations require Vr to be above VMCA - the published performance covers both options. Some operators use Vr < VMCA, and others use Vr > VMCA.
