Dehavilland Twin Otter crash

[Al Jones]

As this is David Morton's favorite aircraft and one he spent a lot of time in, I'm going to ask "what did this guy do to mess up?" Looks to me like he tried to horse it up without enough air speed and it tip-stalled. Your opinion, David? Anybody else with experience in this aircraft?
http://www.youtube.com/watch?v=e0DEb0M6wt4

 

[Pete McCluskey.]

Props not set to fine? Low air speed?

 

[David Morton]

Al - I would not know where to start.
There are so many imponderables that the Video clip cannot address. Those range from AUW (All Up Weight)?, Strip altitude AMSL?, Actual Surface Wind and did it vary
during the run?, Was there any Cross wind (I doubt because the trees are stationary)? Did he have 20 degrees of flap extended? (I cannot be sure looking at the video). Was he cleared for STOL OPS ? ( a definite training course and qualification at DHC or the equivalent and definitely not public transport).
He went past the camera position with the full 50 Lbs Torque and with full up elevator so they were both correct for a STOL departure. Did the right engine
have a moment and the propeller create a problem which may just have stalled the right wing at such a low speed. There are quite a few possible failures on the Twin Otter such as the Beta Back up microswitches in the power lever and the propeller operated Beta Back up Microswitches which if both fail, you have an engine at full power but the prop is driving itself into reverse. (DHC said it was recoverable but I note they demonstrated it and rigged it to happen at 18,000ft and both pilots wearing parachutes) [Loverseed and Hubbard ?]
I think it was quite a high airfield judging by the length of run he took and then it also looked as though he had a power problem as he seemd to continue into a spin to the right manouevre before the terrain interupted his flight. Al, so many questions really it is only conjecture on my part. Bad luck on the day.

 

[David Sturch]

Here's the link on the crash. The U-Tube date threw me off. I dont know if NTSB has a file on the crash. Al if you check through the data base there are a few more. The Otter is getting old. Viking Air In BC has the rights to produce new ones.
Dave
ASN Aircraft accident de Havilland Canada DHC-6 Twin Otter 100 C-FAWC Muncho Lake-Mile 462 Water Aerodrome, BC

 

[David Morton]

David,
I had a look and there was no real findings as to the cause. It was quite full with Fuel as the trip was 685 mils to Vancouver and though that would not be a reason, STOL takeoffs are best done at light weights. Most bush pilots are STOL trained as well or they wouldn't last long in the job. As I previously said there could be a myriad of reasons for this disaster. One fatal was very lucky - normally the outer engine (ie the port

engine in this case swings straight into the cockpit) This happened in Scapa Flow and the propeller cut the shoulder straps free and the guy got away with it. Still - the DHC6 Twin Otter is a magic aeroplane to fly in spite of these foibles. Ar least I loved flying it and especailly in crosswinds. B707 pilots often said the 707 was easier to handle than the Twin Otter in a crosswind. I missed that period and joined the Boeing progression on the B737 with Maersk in Denmark.​

 

[Randy V]

I think it was quite a high airfield judging by the length of run he took and then it also looked as though he had a power problem as he seemd to continue into a spin to the right manouevre before the terrain interupted his flight. Al, so many questions really it is only conjecture on my part. Bad luck on the day.

One of the links took me to the departure field information;

Muncho Lake-Mile 462 Water Aerodrome, BC <TABLE border=0 cellSpacing=4><TBODY><TR><TD vAlign=top><TABLE border=0 cellSpacing=4><TBODY><TR><TD></TD></TR><TR><TD>Country:</TD><TD>Canada</TD></TR><TR><TD>IATA code:</TD><TD></TD></TR><TR><TD>ICAO code: </TD><TD></TD></TR><TR><TD>Elevation: </TD><TD>2681 feet / 817 m</TD></TR></TBODY></TABLE></TD></TR></TBODY></TABLE>
<TABLE border=0 cellSpacing=4><TBODY><TR><TD> </TD><TD> </TD></TR></TBODY></TABLE>

Of course this doesn't speak to the density altitude or how heavily loaded he was..

Pity that one of the passengers perished in this...

 

[David Sturch]

David,
They had three passengers but they could of been carrying alot of gear. I also heard of loads shifting due to poor tie downs, plus the other facts you stated. If you look at the other crashes most were due to weather, hitting snow banks ,fog etc.

There is a new show here on the History Channel here called "Ice Pilots". You should watch a couple of those episodes, based on Buffalo Air out of the Yukon. Scary stuff,
flying a bunch of Antiques in the winter in the middle of nowhere.
Dave