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Twin Otter Mishap Orchid Island 13 April 17

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Twin Otter Mishap Orchid Island 13 April 17

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Old 14th Apr 2017, 16:08
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Twin Otter Mishap Orchid Island 13 April 17

Twin Otter crashes at Orchid Island Airport, 4 injured | Society | FOCUS TAIWAN - CNA ENGLISH NEWS

https://aviation-safety.net/database...?id=20170413-0

Lucky no one seriously hurt. They had just gotten these not long ago to replace some very old Dornier 228.
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Old 14th Apr 2017, 16:31
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Strong cross winds are manageable with the Twin Otter, but the tiller should not be touched during the landing roll! Or during the take off roll for that matter. It wouldn't be the first time a pilot tries to steer with the tiller and ends up in the ditch
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Old 14th Apr 2017, 17:46
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Very true. We had a new Twin Otter captain do this on takeoff at a military base down in South America. They already were unhappy due to a weather diversion in landing there. They put them under house arrest after their excursion and a new crew had be flown all the way down to pick up the aircraft.
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Old 14th Apr 2017, 23:00
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Strong cross winds are manageable with the Twin Otter

True, but you do need to move your hands and feet - a declining skill, unfortunately!
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Old 15th Apr 2017, 03:30
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Crosswinds on the Twin Otter are certainly manageable but it keeps you on your toes...

You need to pay attention, the wind hits it a bit harder than other types with that tall tail, though it's the same tail and the massive movement from the rudder what helps you fight the crosswinds.

Could it be a case of improper landing technique?
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Old 15th Apr 2017, 08:11
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Strong gusting crosswinds are the ones that can catch you out, a sudden gust can have you in the weeds rather quickly. Greasers are bad, you need to get all of the weight on the wheels ASAP.
Probably bad habits by a crew newly converted from the DO228.
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Old 15th Apr 2017, 11:00
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Many years ago. Gusting crosswind, which dumped the port wing lower than intended just as aileron effectiveness was lost. The result was the outboard aileron hinge scraping along the runway, until enough speed was lost to allow the aircraft back onto its wheels again. I'm told that from the outside it looked quite spectacular.
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Old 15th Apr 2017, 17:34
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Orchid Island and Green Island where these planes fly are known to have high winds and similar mishaps have occurred there with the Dornier 228 that they finally retired.

Is the Twin Otter harder to handle in high winds than the Dornier? Could be the pilots transitioning from the Dornier need more time.
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Old 15th Apr 2017, 17:42
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I didn't fly the Do but I reckon it has higher operational speeds. They're both STOL if I'm not mistaken, but maybe the lower speeds and the higher lift characteristics of the Otter can make for a gust or something to shake it off its path easier?

Though as a pilot you should be able to handle it with proper landing technique. As the ancient geek puts it, no greasers for starters. Using the props in an effective manner is also helpful as it helps to control the "airborne-mind" of the Otter at touchdown when it's carrying a couple extra knots...
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Old 15th Apr 2017, 19:32
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Indeed, its all about directional stability.
In the air speed = momentum = stability.
On the ground directional stability comes from having the wheels firmly on the ground.
So touching down firmly with a bit of extra speed gets you through the vulnerable bit as quickly as possible. But not enough speed to make it float in ground effect.

All STOL types have this vulnerability due to their low touchdown speed.

Last edited by The Ancient Geek; 15th Apr 2017 at 19:51.
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Old 16th Apr 2017, 00:39
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https://www.youtube.com/watch?v=fjfw60krv68

Any landing that you can use the plane again is a good landing on Orchid Island.
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Old 16th Apr 2017, 05:03
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The Twin Otter handles a strong crosswind very well. Being a high wing aircraft, you can lower that wing down into the crosswind a significant amount. It has a big rudder which also helps. I don't know the length of this runway but in non-STOL ops at flaps 20, it can still land in a fairly short distance.

The runway looks reasonably long in the video. I think a better landing technique might have been a fair amount of wing down and a better flare instead of forcing it on. The wind wasn't even that strong or at too much of an angle to the runway according to the windsock.
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Old 16th Apr 2017, 08:59
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Quite a bit of damage:

https://www.youtube.com/watch?v=mbcKiRYBG4M

https://www.youtube.com/watch?v=_XlqHXfdIhU

beyond economic repair perhaps?


Direction Length Surface

13/31 1,123m 3,684ft Paved

Previous Daily Air incident with a Do 228

https://www.asc.gov.tw/upload/acd_at...%20Summary.pdf
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Old 16th Apr 2017, 11:10
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The Twin Otter handles a strong crosswind very well
Yup - those oldpharts among us who came to the twotter from the AN2 thought we had arrived in crosswind heaven. But a strong gust could still bite you on the backside.
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Old 16th Apr 2017, 11:35
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That Twin Otter will be rebuilt. If too many "parts" are needed for the repair, it could be that Viking is asked to produce a cockpit subassembly to splice in. Viking has made subassemblies to enable such repairs before. I would expect that it will return by ship to one of several North American facilities for repair.

On the ground directional stability comes from having the wheels firmly on the ground.
So touching down firmly with a bit of extra speed gets you through the vulnerable bit as quickly as possible. But not enough speed to make it float in ground effect.
Or, as long as the weight of the aircraft is not firmly on three wheels, assure that you are still using the flight controls to maintain control. Even with weight on the nosewheel, at "speed", the rudder is effective enough to scrub the tire, which is as it should be - the flight controls maintain control. However, reverse can be a factor too...

Though I have no idea if it a factor in this event, applying reverse too aggressively or unevenly can cause rapid loss of directional control. Reverse interrupts the effective airflow over the tail, so it works much less well to keep the plane straight, and if applied too rapidly, may be unsymmetrical in effect due to spool up times. This has been the cause of a number of Twin Otter and Buffalo accidents.

A Twin Otter is not equipped with anti skid, so on a wet runway, too much application of brakes can get you in trouble, locking wheels, which can then slide sideways.

A 3600 foot runway is ample for a nice unbraked, non reverse, landing in a Twin Otter. "STOL" technique is not required for that runway, and I doubt operationally approved anyway.
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Old 16th Apr 2017, 16:24
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Originally Posted by armchairpilot94116
https://www.youtube.com/watch?v=fjfw60krv68

Any landing that you can use the plane again is a good landing on Orchid Island.

Zero crosswind controls. Makes it look worse than the conditions warrant.
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Old 16th Apr 2017, 18:25
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1100 meters is enough for a flap 20 landing which helps a bit to fight a crosswind. +1 on the brakes and reverse re Step Turn. You could even afford to fly it down with a bit of power and wing down until touchdown and then using reverse sensibly. A couple of extra knots should help if the wind is particularly strong. Runway surface looks good, braking shouldn't be an issue

Something must have gone particularly wrong in this case.
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Old 16th Apr 2017, 18:57
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from the first video we notice that flaps are set at 20.

Flaps 20 for normal landings (normal runways).
Flaps 40 only for extremely short runways (e.g., with high trees at each end); or for training.
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Old 17th Apr 2017, 02:06
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Flaps 40 in a Twin Otter requires piloting skills just a little beyond the standard Caravan/Navajo/King Air. It's easy to get too much weight on the nose wheel, or even wheelbarrow it, which I have seen done. The nose wheel area (known as "station 60") is a little vulnerable to hard landings on the nose wheel. I was always afraid to be responsible for damage in general, and station 60 in particular - so I kept the nose light.

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...
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Old 17th Apr 2017, 16:05
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Originally Posted by Step Turn
That Twin Otter will be rebuilt. If too many "parts" are needed for the repair, it could be that Viking is asked to produce a cockpit subassembly to splice in. Viking has made subassemblies to enable such repairs before. I would expect that it will return by ship to one of several North American facilities for repair.



Or, as long as the weight of the aircraft is not firmly on three wheels, assure that you are still using the flight controls to maintain control. Even with weight on the nosewheel, at "speed", the rudder is effective enough to scrub the tire, which is as it should be - the flight controls maintain control. However, reverse can be a factor too...

Though I have no idea if it a factor in this event, applying reverse too aggressively or unevenly can cause rapid loss of directional control. Reverse interrupts the effective airflow over the tail, so it works much less well to keep the plane straight, and if applied too rapidly, may be unsymmetrical in effect due to spool up times. This has been the cause of a number of Twin Otter and Buffalo accidents.

A Twin Otter is not equipped with anti skid, so on a wet runway, too much application of brakes can get you in trouble, locking wheels, which can then slide sideways.

A 3600 foot runway is ample for a nice unbraked, non reverse, landing in a Twin Otter. "STOL" technique is not required for that runway, and I doubt operationally approved anyway.
Right now there is a japanese twotter in yyj getting rebuilt due to the same finger problem. Basically a new assy from the wings forward.
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