Twin Otter crash at Muncho Lake, July 2007

[Mark Rose]

https://www.youtube.com/watch?v=e0DEb0M6wt4


After watching that, and reading the CANDORS, I have a question: what reason would the pilot have for rolling right so soon after take off? Or was it simply that he knew he couldn't get lift over the cable on the other side of the highway and was trying to turn down the highway?

[timel]

4. The take-off was attempted in an upslope direction and in light tailwind, both of which increased the distance necessary to clear the existing obstacles.

[Redneck_pilot86]

More to the point:

1.The take-off was attempted at an aircraft weight that did not meet the performance capabilities of the aircraft to clear an obstacle and, as a result, the aircraft struck a telephone pole and a telephone cable during the initial climb.

[trey kule]

After watching that, and reading the CANDORS, I have a question: what reason would the pilot have for rolling right so soon after takeoff? Or was it simply that he knew he couldn't get lift over the cable on the other side of the highway and was trying to turn down the h

I would guess the roll was uncommanded. This is what an insipion spin looks like.

[Mark Rose]

I would guess the roll was uncommanded. This is what an insipion spin looks like.

Ahh, okay. Thanks!

[timel]

Upslope, tail wind and overweight take off. That is a winning package for airmanship of the year!

Captain and CP was 6000 hrs and FO was 10000 hours.

[Mark Rose]

I guess taking short cuts and chances caught up to them...

[Napoleon So Low]

This is what an insipion spin looks like.

Say what??

in·cip·i·ent
inˈsipēənt/
adjective: incipient

in an initial stage; beginning to happen or develop.
"he could feel incipient anger building up"

[trey kule]

Thank you,

[Redneck_pilot86]

Upslope, tail wind and overweight take off. That is a winning package for airmanship of the year!

Captain and CP was 6000 hrs and FO was 10000 hours.

Don't forget not backtracking all the way.

[MUSKEG]

Aircraft was NOT over gross and used all the runway available. The correct term would be, to heavy for conditions and runway length or as was pointed out (quote:: at an aircraft weight that did not meet the performance capabilities of the aircraft).

[Redneck_pilot86]

Findings as to cause #3. The southeast end of the airstrip was not clearly marked; as a result, the take-off was initiated with approximately 86 feet of usable airstrip behind the aircraft.

They did not use all the runway available.
Also, nobody is claiming it was over gross. It was overweight for what was being attempted.

[MUSKEG]

Quote
"Upslope, tail wind and overweight take off. That is a winning package for airmanship of the year!"

I beg to differ.

[timel]

Quote
"Upslope, tail wind and overweight take off. That is a winning package for airmanship of the year!"

I beg to differ.

The best is when you have those charts you can use, you compute your weight (and it fits in), altitude density, winds, sometimes runway slope and it gives you a distance.

Hope that attempt was not for the camera.

[pdw]

I have a question: what reason would the pilot have for rolling right so soon after take off?

Right aileron (to steer slightly right) prior to VR ... could do that.

[Pop n Fresh]

This is what an insipion spin looks like.

Say what??

in·cip·i·ent
inˈsipēənt/
adjective: incipient

in an initial stage; beginning to happen or develop.
"he could feel incipient anger building up"

Best first post for August.

[Redneck_pilot86]

Quote
"Upslope, tail wind and overweight take off. That is a winning package for airmanship of the year!"

I beg to differ.

Beg all you want. Overweight for a given take off does not mean over gross weight, it only means they were over the weight at which the aircraft could successfully complete the take off. I think its pretty clear that they were overweight for this attempted takeoff.

[MUSKEG]

And that's exactly what I stated.

[Napoleon So Low]

Best first post for August.

Pop was once a bovine fancier. CS was once Harvey K. And Napoleon was ?? Stay tuned....

[Redneck_pilot86]

And that's exactly what I stated.

What you said was:

Aircraft was NOT over gross and used all the runway available. The correct term would be, to heavy for conditions and runway length or as was pointed out (quote:: at an aircraft weight that did not meet the performance capabilities of the aircraft).

As I stated, nobody anywhere on this thread has ever said that the aircraft was over gross. You then proceed to say that the aircraft was over the weight which was suitable for the conditions..ie overweight. The aircraft was not over gross, but was over weight. I don't understand what you are begging to differ about. These are all facts from the TSB report.

[pdw]

(quote:: at an aircraft weight that did not meet the performance capabilities of the aircraft).

Yes ... but actually, it "did not meet the performance capabilities" .. for that runway length/TODA

The aircraft was not over gross, but was over weight.

Yes ...was not overweight (what is meant when saying [over gross or heavier than MTOW] ) ... but that quote is basically saying it was 'not loaded lightly enough' for this shortened / upslope runway distance with an increasing component from tail-quartering (see the report .. the warning phone call from the colleague at the other strip there ..which unfortunately came just-a-bit too late)

[Redneck_pilot86]

(quote:: at an aircraft weight that did not meet the performance capabilities of the aircraft).

Yes ... but actually, it "did not meet the performance capabilities" .. for that runway length/TODA

The aircraft was not over gross, but was over weight.

Yes ...was not overweight (what is meant when saying [over gross or heavier than MTOW] ) ... but that quote is basically saying it was 'not loaded lightly enough' for this shortened / upslope runway distance with an increasing component from tail-quartering (see the report .. the warning phone call from the colleague at the other strip there ..which unfortunately came just-a-bit too late)

Wrong. Overweight is not necessarily over gross. Not all strips are capable of supporting operations of a given aircraft type at gross weight. "Weight" is the maximum operating weight that a given condition will allow. Over that weight, you will crash at the far end of the strip, as this crew did.

The weight and balance report indicated the aircraft was at 9955 pounds, or 1624 pounds under the maximum gross weight of 11 579 pounds at take-off. The aircraft had been filled with Jet A fuel and the fuel weight had been calculated as 2500 pounds. The useable fuel capacity of the Twin Otter is 315 imperial gallons. The operations manual referenced a weight of 8.4 pounds per imperial gallon for Jet A, for weight and balance purposes. At 8.4 pounds per imperial gallon, a full load of fuel would weigh 2646 pounds. Allowing for fuel burn for start and taxi, the fuel load at take off would likely have been 2600 pounds.

There was no evidence to indicate that the weight of the onboard tie down straps and survival gear had been accounted for in the weight and balance report. Journey log records indicated the survival gear weighed 60 pounds and the tie-downs were estimated to weigh about 10 pounds. Including the additional fuel, survival gear and tie-down weights, post-accident calculations indicated that the aircraft was at or slightly above 10 100 pounds at take-off.

So the twin otter departed at about 10, 100 lbs. Clearly this was more than the conditions would allow, therefore it was overweight.

Using normal take-off technique with 30 degrees (sic) of flap on a dry, level concrete surface, the maximum weight at which the aircraft could clear a 50-foot obstacle with 1250 feet of take-off distance available in the existing wind and temperature conditions was 8900 pounds. To achieve these take-off distances, all take-off procedures required take-off power to be applied before brakes are released. The take-off charts did not provide any means to compensate for the uphill slope of the runway or the gravel surface, both of which would have increased the distance needed to take-off and clear a 50-foot obstacle.

Any weight over 8900 lbs (less actually, as it was a gravel, sloped runway and take-off power was not applied prior to brake release) is overweight. This aircraft was overweight, and crashed because of it.

[GyvAir]

I don't understand what you are begging to differ about.

Maybe:

That is a winning package for airmanship of the year!

?

[pdw]

I understand what's being said there, GYVair.

Let's say when you call in for a ferry flight to take that extra ton of fuel, say on a Caravan going across the ocean; in such case you the pilot are taking off heavier than a normal MTOW for your plane ... at a weight that is over (or beyond) what is usually the MTOW, but now not overweight in that sense either because you called in for the ferry permit and also planned for any extra payload's performance requirements.

It's clear, if you are underweight for your MTOW you can still be overweight for the conditions; that's probably why the report worded it very carefully: " at an aircraft weight that did not meet performance capability..... ".

Using the words 'did not meet' in that context (while we know they could have said 'at an aircraft weight that was greater than ') is less confusion IMO than trying to describe it as "overweight" (using the OW-word) there, which perhaps too easily gets taken to mean 'heavier than the MTOW'.

I get it, that here it was important to discern the OW is not about an overloading above the manufacturer's POH limit, but that it is an overloading none-the-less (yes 'an overweight') for the reduced performance produced with this combination of take-off conditions listed in the report. The amount of upslopeis yet undetermined, with the end of the useable runway 'not well defined' (not all TDA is used) .. and finally, the tail-quartering details are not exactly known, where the warning/pirep of an increasing southerly component was transmitted to them just as the accident had occurred (from another aircraft at a second airstrip nearby ).

[CFR]

The report is not necessarily aimed at the masses so the wording is somewhat immaterial. The description is/should be clear for a pilot. Takeoff performance charts are available for most if not all A/C. I would suggest that the actual numbers are a bit better than the average pilot would get on any given day, but they will give you a go/no go line. The closer to the line the sharper your pencil needs to be and more critical becomes your decision making! Once you start adding in gravel surface and upsloping runway then the numbers change and not for the better! Congratulations you are now a test pilot!

see pages 4-6-1 and 4-6-2 for a clear explanation.

http://www.caamsllc.com/Performance%20D ... -6-300.pdf