Dolly Departure

[pelmet]

Occurrence No. : A12W0152 Occurrence Type: ACCIDENT
Class : CLASS 5 Reportable Type:
Date : 23-10-2012 Time : 10:06 PDT
Region of Responsibility : WESTERN
Location : CYXY WHITEHORSE INTL, YUKON

Never seen one of these before....

Aircraft Information:

Registration : C-GMGD Operator : ALPINE AVIATION
Manufacturer : DE HAVILLAND Operator Type: COMMERCIAL
Model : DHC-2 MK I CARs Info: 703 - AIR TAXI
Injuries: Fatal : 0 Serious : 0 Minor : 0 None : 1 Unknown : 0


Occurrence Summary :

A12W0152: The Alpine Aviation de Havilland DHC-2 MK1 Beaver (C-GMGD), was attempting a dolly departure from Whithorse Intl, YT. The aircraft floats slid on the surface of the dolly and collided with the rear of the pickup truck pulling the dolly. The propeller struck the pickup just aft of the rear window. Both vehicles ended up just off the end of the runway. There were no injuries

[cgzro]

[youtube]http://m.youtube.com/watch?v=7U7SBGfT2No#[/youtube]

I filmed this a couple of years ago through the sunroof of the truck ...
scary...

[Siddley Hawker]

Why would you want to pull the dolly behind a truck to take off? Doesn't seem to make a whole lot of sense. We used to pull the airplane out to then runway behind the truck, unhook the towbar and then launch off the dolly. There was a lever on one of the float cradles that was kept retracted by the weight of the airplane, and as soon as the airplane lifted off it popped up and applied the brakes on the two rear wheels.

[switchflicker]

We did the same thing except the brakes on the dolly were activated by a nitrogen charge deployed when a string tied to the spreader bar was pulled. This happened when the aircraft was about two or three feet above the dolly.

[shimmydampner]

Why would you want to pull the dolly behind a truck to take off? Doesn't seem to make a whole lot of sense.

It's done fairly regularly, most often without incident. Requires a bit of coordination and communication between the driver and the pilot. It's lots of fun!
I'm just speculating but perhaps airport managers don't want or can't allow unmanned uncontrolled trailers surfing around airside at high speeds taking out runway lights and the like?

[cgzro]

Or hitting a vasis or ils ... also vehicles on runway have to have lights and 2 way coms etc.

[Siddley Hawker]

Our procedure was to tow the airplane out to the runway, do a quick run-up, disconnect the tow bar and blast off. We always had a vehicle from airport security with us, and I can only remember the dolly running off the side of the runway once. That was some local hero with a 180 and bigger balls than brains who should have known better than to try and fly the airplane off himself. The guy jammed the power on and the 180 immediately began to swing left. He eventually got airborne, but he was off the side of the runway when he did, scared the living shit out of himself. The Beaver was easier than the 185, I seem to recall. As soon as you had some slipstream over the rudder you could trundle it around like a car. Start with climb flap and pop it off with takeoff flap at around 50 kt. At Northern Wings you were supposed to buy the beer if the dolly didn't stop on the center line.

[magic wand]

I wonder why they were doing this at this time of year. Usually spring is the season for float plane launching.

Bet the feller in the truck needed new underwear.

[looproll]

here is one caught on tape:

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

[Taiser]

Could the truck have just been taking the airplane out for departure and not unhooked yet? I've seen dolly departures before but not being actively towed! Might be a typo in that report? That video looks dangerous as hell, can't believe that's legal, at least not here in our over-regulated country! Cool as hell mind you...

[Pavese]

here is one caught on tape:

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

From the Youtube page:

"Top Comment:

And the Jetstream was next or what? "

LOL!

D

[shimmydampner]

Could the truck have just been taking the airplane out for departure and not unhooked yet? I've seen dolly departures before but not being actively towed! Might be a typo in that report? That video looks dangerous as hell, can't believe that's legal, at least not here in our over-regulated country! Cool as hell mind you...

Well I have done towed dolly departures before and I can assure you they are not "dangerous as hell." As I stated above they do require good communication and coordination between the pilot and the driver. It also requires a certain technique and good timing in terms of the application of power and pitch. Obviously when at near takeoff speeds and in such close proximity to a vehicle the margin for error is a couple feet and maybe a second or two.
I don't think it would be a typo in that report. The amount of power required to slide an aircraft forward on its floats on a dry surface, while at taxi speeds (producing negligible lift) is considerable. Unless the truck was going too fast and really slammed on the brakes, I can't imagine that being a realistic possibility.
Sid, how tough was it to get the dolly to stop on the centre line? I imagine them not tracking very straight once the aircraft is away. Was there a lot of beer bought on launch days?

[Siddley Hawker]

SD I did about 8 or 10 dolly takeoffs, mostly with the Beaver. It was normally the CP's job, but the first one I did I came back with the airplane on skis at around 2 PM one day and launched the next day ay 10 AM with the same airplane off the dolly. The CP was out of town. I asked around and was told it was no biggie, just make sure not to jam the power up before you got rolling properly. I lined the airplane up about 10 degrees right of centerline and fed the power in slowly. There's lots of rudder control at about what? 20 kt. I started with climb flaps and dropped takeoff flaps at around 50, and the thing popped off nice as could be. Where the dolly stops is more a result of the brakes, if one is a little draggy it'll pull to that side. When I started to fly corporate the company had the Beaver you see there, and Labrador Mining put me on their insurance to fly their Beaver, IUU, so once a year I was elected if the regular Beaver driver was off. (He always was.)

[Inverted2]

Those Germans were doing dolly takeoffs before it was even cool.

[Nahanni]

Unfortunate to hear of this accident. I actually ferried the new Beaver to Alpine Air a few weeks prior and did a dolley launch out of Fort Nelson, BC to get to whitehorse. It was my first dolley launch and the wise advice of my boss to put the sleeping bag from the back of the cabin under my ass so that I could see the truck the whole time was a great idea that I wanted to share. I"m 6'2" and the extra height made it a breeze to keep an eye on the truck and make certain I wasn't slidding forward on the dolley.

Enjoy the winter all! We're already in full winter mode here in Fort Simpson, NT.