Twin Otter crash

[fholbert]

Date:	Saturday 20 May 2023
Time:	c. 14:15
Type:	Viking Air DHC-6 Twin Otter 400
Operator:	Seafly LLC
Registration:	N153QS
MSN:	869
First flight:	2012
Crew:	Fatalities: 2 / Occupants: 2
Passengers:	Fatalities: 0 / Occupants: 0
Total:	Fatalities: 2 / Occupants: 2
Aircraft damage:	Damaged beyond repair
Location:	54 km (33.8 mls) W off Half Moon Bay Airport, CA (HAF) ( Pacific Ocean)
Phase:	En route (ENR)
Nature:	Ferry/positioning
Departure airport:	Santa Rosa-Sonoma County Airport, CA (STS/KSTS), United States of America
Destination airport:	Honolulu-Daniel K. Inouye International Airport, HI (HNL/PHNL), United States of America

Narrative:
A DHC-6 Twin Otter 400, N153QS, crashed into the Pacific Ocean about 54 km west of the Half Moon Bay Airport (HAF), California.
The aircraft had departed Santa Rosa-Sonoma County Airport, California (STS) at 15:21 UTC (08:21 local time) on a flight to Honolulu International Airport, Hawaii (HNL).
ADS-B data suggests that the aircraft at some point turned back, heading for HAF, until it crashed at 14:15 local time.

 

[CFI A&P]

These planes are regularly tanked with a 1,000 gallon bladder in the cabin, and operating on a ferry permit long legs over water.

About 30 years ago a similar accident occurred, with survivors and the culprit was a flow problem. They had the fuel but couldn’t pump it to the engines.

 

[Murdoughnut]

These planes are regularly tanked with a 1,000 gallon bladder in the cabin, and operating on a ferry permit long legs over water.

About 30 years ago a similar accident occurred, with survivors and the culprit was a flow problem. They had the fuel but couldn’t pump it to the engines.

Would it be SOP to carry chutes on board to avoid having to ride it out into a rough sea?

 

[MikeD]

Would it be SOP to carry chutes on board to avoid having to ride it out into a rough sea?

You would have to ditch in order to be able to deploy any onboard life raft. If you bail out at altitude, the only flotation item you’ll have at best is an inflatable life preserver once you reach the ocean. Either way is rough, as I can’t imagine the DHC-6 is a good ditching aircraft at all just with its design of fixed landing gear and high wings.

 

[Inverted]

I believe N153QS was an amphib Twin Otter which makes this much more odd. The thing had floats...

 

[CFI A&P]

Would it be SOP to carry chutes on board to avoid having to ride it out into a rough sea?

Rafts and jackets, most likely. Parachutes - unlikely. The cockpit doors are forward of the propeller arc - about the same results as ejection seats in a helicopter. The rear doors are 20’ behind you, so you’d have to unbuckle or remove the harness, hopscotch through the fuel bladders in the cabin to get to those doors.

I believe N153QS was an amphib Twin Otter which makes this much more odd. The thing had floats...

True, but float planes have limits on how much surf they can tolerate. Calm seas would be easy, but NOAA buoys off of the Bay Area currently show 15kts of wind with 6’ - 9’ swells. Trying to land in the trough and then hitting the 6’ crest at approach speed would be about the same as hitting a brick wall.

A quick search on the Albatross says 4’ seas were common, and max of 10’ but the takeoff would require JATO rockets to power through the swells.

 

[ahw01]

looks like it had been converted to wheels

I believe N153QS was an amphib Twin Otter which makes this much more odd. The thing had floats...

 

[fholbert]

I believe N153QS was an amphib Twin Otter which makes this much more odd. The thing had floats...

I’d think the floats would be removed for the trip. Lot of drag.

 

[///AMG]

Realistically, much more than a couple miles out to sea, on that coast, and regular people would be dead without dry suits.....and that is assuming that egressing from a sinking ditched airplane would go easily (which it wouldn't). Might be able to float for 30 mins or so before you lose ability to move the limbs. Probably not the answer most want, but coastal SAR is time-distance troubled in their slow helos. Paging the guys from miramar who spent 4 hrs in the water post ejection, not much more offshore than this plane, at night, who were in drysuits and still had life threatening hypothermia.

BLAB.....you go down of the coast of CA, you're probably not gonna make it without uncle sam's protective gear and immediate SAR response.

 

[Cherokee_Cruiser]

“
BLAB.....you go down of the coast of CA, you're probably not gonna make it without uncle sam's protective gear and immediate SAR response.


”


Ugh. I remember a few years ago some coastal airport in CA, a young couple (I think on a date) took off in a single engine aircraft, disappeared, never to be seen again. A mystery to this day. I’ll try and dig up that accident…

 

[mechan9]

Was it the Shelter Cove one?

Accident Piper PA-28R-180 Arrow N4958J,

A witness reported that the pilot and passenger departed in dark night conditions with no visible horizon. After takeoff, the airplane made a left turn. Flight track data first identified...

aviation-safety.net

Piper PA-28R-180 Arrow, N4958J: Fatal accident occurred October 23, 2019 in Shelter Cove, California

Kayla Rodriguez, 27 and Justin Winfrey, 43. This is preliminary information, subject to change, and may contain errors. Any errors in this ...

www.kathrynsreport.com

https://kymkemp.com/2019/11/05/families-of-two-missing-in-plane-suspend-search/

Green said Winfrey had a rough set down. But he and Rodriguez exited the plane safely. “I could tell he was kind shaky,” Green said. “I didn’t know if he didn’t want to admit making a bad decision in front of his passenger, but I could see he was uneasy…I don’t think she thought there was anything out of normal.”

He offered the two a ride, but they said they were going to Gyppo Ale Mill.

“Just shy of 9 o’clock, we heard the plane take off again,” Green said.

When the two didn’t return home, family and friends started investigating. They learned from authorities that radar last showed the plane several miles west of land over the Pacific Ocean roughly about 9:15 p.m.

 

[Skåning]

Not all ditchings end badly:

 

[Murdoughnut]

Not all ditchings end badly:

Man, I had never heard of that before, but the ADM that went into to ensure everyone survived is absolutely amazing!

Pan Am Flight 6 - Wikipedia

en.wikipedia.org

 

[CFI A&P]

looks like it had been converted to wheels

It sounds like you are correct. Someone in another group says it was on wheels at the time.

I’d think the floats would be removed for the trip. Lot of drag.

The floats are about a 15 knot drag penalty, and if is amphibious, that system eats up some useful load when installed.