Old 07-06-2014, 11:33 AM   #1
ErezS
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Default Eleven killed in Polish skydiving plane accident

Another sad news, this time from Poland:

Piper Navajo carrying 12 people crashed and burst into flames in Topolów, southern Poland, shortly after takeoff
http://www.theguardian.com/world/201...sh-eleven-dead

http://www.rte.ie/news/2014/0705/628796-poland-crash/

http://www.foxnews.com/world/2014/07...ash-in-poland/

RIP
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Old 07-06-2014, 09:09 PM   #2
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11 people in a Navajo?
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Old 07-07-2014, 04:48 AM   #3
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11 people in a Navajo?
Frankly, it's looks strange to me as well. But this is what they wrote.
Maybe there is someone with more accurate information?
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Old 07-07-2014, 06:23 AM   #4
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12 in a Navajo!!!
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Old 07-07-2014, 04:24 PM   #5
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The cause of the crash is being investigated. Firefighters say that the Piper Navajo aircraft may have been overloaded.
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Old 07-07-2014, 09:40 PM   #6
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When I look here ( http://en.wikipedia.org/wiki/Piper_PA-31_Navajo ) I see 10 seats.

So pull the seats, leave off some gas (they aren't going very far), and what's the big deal? I don't know it's that unusual for skydiving operations.

You also have to figure on that Russian-Poland influence and that they may have been moving trees and generating fog banks and mis-adjusting the navigation beams....
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Old 07-09-2014, 12:28 PM   #7
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Originally Posted by 3WE View Post
When I look here ( http://en.wikipedia.org/wiki/Piper_PA-31_Navajo ) I see 10 seats.

So pull the seats, leave off some gas (they aren't going very far), and what's the big deal? I don't know it's that unusual for skydiving operations.

You also have to figure on that Russian-Poland influence and that they may have been moving trees and generating fog banks and mis-adjusting the navigation beams....
Only the stretched Chieftain could seat 10, and then not very comfortably. The "short" Navajos are 8-seaters and get pretty cozy with that load.
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Old 07-10-2014, 10:27 PM   #8
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A report by the Flight Safety Foundation said the Piper twin, registered to an owner in Merrimack, New Hampshire, and operated by the Omega Skydiving School, had a history of engine problems.

Eyewitnesses reportedly stated that the Navajo’s left engine quit just before the crash.

Read more at http://www.flyingmag.com/technique/a...gGliGKW1RTE.99
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Old 07-11-2014, 01:04 PM   #9
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Originally Posted by ATLcrew View Post
Only the stretched Chieftain could seat 10, and then not very comfortably. The "short" Navajos are 8-seaters and get pretty cozy with that load.
Thanks...

Ok a 50% overload (crude estimate) is pushing it- even for more "lawless-throw-caution-into-the-wind" operations.
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Old 07-11-2014, 01:41 PM   #10
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Originally Posted by 3WE View Post
a 50% overload (crude estimate)


How do you get to that "crude" estimate?
Ok, you have 50% more people, but do you have 50% more engines, wings, landing gears?
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Old 07-11-2014, 03:10 PM   #11
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How do you get to that "crude" estimate?
Ok, you have 50% more people, but do you have 50% more engines, wings, landing gears?
??????

I do not understand your question.

First- my frame of reference is an "other than first world parachute operation"...right or wrong, there's probably some rule bending with some operators.

I originally stated that 12 folks on a 10-seat plane isn't all that overloaded (Especially in my frame of reference).

ATL corrected me that it was more like an 8-seat plane.

Ok 12 folks on an 8-seat plane is roughly (very roughly) 50% overloaded using basic parlour weight and balance calculations and is a fairly significant overload very possibly contributing to the crash.

That's all I was trying to say.

I do not know where you are going with your comment about 50% more engines.
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Old 07-11-2014, 05:21 PM   #12
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Originally Posted by 3WE View Post
??????

Ok 12 folks on an 8-seat plane is roughly (very roughly) 50% overloaded using basic parlour weight and balance calculations and is a fairly significant overload very possibly contributing to the crash.

That's all I was trying to say.

I do not know where you are going with your comment about 50% more engines.
I'm going to... ok, never mind. I (worngly?) took "50% overload" as "50% overweight".

Empty weight: 3930 lb
MTOW: 6500 lb
Allowed Useful load: 2570 lb
12 adults with parachutes = 200~220 lb x 12 = 2400~2800 lb.
Fuel: No idea. Let's asume that it had not much (15~40 USGal/wing?), so it's 30~80 USGal x 6 lb/USGal = 180~480 lb.
Total useful load = 2580~3280 lb
That's 10~710 lb above the allowed useful load and above the MTOW.
And that's 0.4~28% overload or 0.15~11% overweight.
With a 15% overweight the stall speed increases by 7%, from 64 to 68 kts.
The Vmc doesn't change, and neither does the blue-line climb speed (best climb with one engine inop), but what does change (worsens) is the climb rate at said (or any) speed. Being overweight is not the right time to lose an engine.
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Old 07-11-2014, 08:10 PM   #13
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That's 10~710 lb above the allowed useful load and above the MTOW.
And that's 0.4~28% overload or 0.15~11% overweight.
Indeed.

And, yes, the denominator matters.

50% more people that it's people capacity...

...but that is not 50% more weight than it's total weight capacity...

(This and the speed comment below is why I said 12 folks on a 10-seat airplane is not necessarily a clear cause)

And if the CG is OK and the altitude is OK and the engines are OK and you have extra runway, it will fly just fine as long as you don't do the equivalent of "four one oh" 'ing it...

And- bring on the lesson that available lift ~ speed^2 AND that grossed out with healthy airspeed, you can pull 2 G in a 60 degree bank and not only didn't died, but didn't descended nor didn't violated any law or aircraft restriction, nor didn't spilled the drink service when you takeded a picture for a flight report.

Nonetheless- 50% more folks on this aircraft is pretty significant by any denominator and does tend to mess with CG and feel and performance and is a likely suspect to be a contributing factor.
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Old 07-11-2014, 10:39 PM   #14
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Denominators, denominators....

Who was the asshole that invented them?
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Old 07-11-2014, 11:07 PM   #15
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FFS ! Why are we all arguing the toss about this ?

12 people went up in a plane designed for 8. An engine failed and 12 people died.

......and all you can do is have an "I can piss higher up the wall than you" competition. Wake up, it ain't rocket science. I can give you 5 personal experiences of this happening in the past, either from engine failure or weight overloading or a combination of both.
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Old 07-12-2014, 12:13 AM   #16
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FFS ! Why are we all arguing the toss about this ?

12 people went up in a plane designed for 8. An engine failed and 12 people died.

......and all you can do is have an "I can piss higher up the wall than you" competition. Wake up, it ain't rocket science. I can give you 5 personal experiences of this happening in the past, either from engine failure or weight overloading or a combination of both.
The thing is that:
- The fact that 12 people climbed in an airplane designed for 8 (design that includes 8 seats, probably 6 of which were removed) doesn't necessarily mean that the plane was overweight.
- An engine failure in this twin doesn't need to lead to an accident, since this plane has single-engine climb capability.
- If the plane was overweight, very likely it was just "slightly" overweight (say 15%). That by itself shouldn't cause an accident. I don't know of any case where a slight overweight caused an accident by itself.

Now:
- Engine failures in twins have caused many fatal accidents, even with no overweight, mostly when the pilot was unable to keep the plane under control.
- Slight overloads have caused accident, many times when the plane was operating at the limit of it's "non-overweight" performance to begin with (example: high and hot).
- An engine failure and an overweight, even is slight, is a recipe for disaster, since this kind of light twins have a positive but slim single-engine performance even if not overweight.

So yes, very likely an engine failure, an overweight, or both, were contributing factors in this accident. Still, the high fatality of this accident makes me thing that that alone is not enough. If an engine fails and you can't achieve a positive climb, then trade altitude for speed, keep the speed above Vmc (and preferably at the blue line) and land wherever you can. The result will be likely a survivable off-field landing. This case, instead, sounds like an out of control scenario, and you can't blame the engine failure alone, and even less the overweight, for that.
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Old 07-12-2014, 12:34 AM   #17
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...Indeed.

And, yes...
I am not arguing (see quote above)

But I am pissing higher than Brian.

Gabriel- I dunno...I can think of a lot of crashes from light planes that are heavily loaded. As usual- your comments are factually correct; however, I'm willing to bet a beer that "W/B" is a significant contributing factor- even if you factor for a light fuel load, missing seats and doors and use gross weight as the denominator.
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Old 07-12-2014, 01:23 AM   #18
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And I agree.

I've said a slight overweight alone.
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Old 07-12-2014, 09:27 AM   #19
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Aircraft was N11WB, a PA-31P Navajo.
Pressurized version of the PA-31 Navajo, powered by two 425-hp (317-kW) Lycoming TIGO-541-E1A piston engines.

General characteristics

Crew: one or two
Capacity: five to seven passengers

Length: 32 ft 7½ in (9.94 m)
Wingspan: 40 ft 8 in (12.40 m)
Height: 13 ft 0 in (3.96 m)
Wing area: 229 sq. ft (21.3 m²)
Empty weight: 3,930 lb (1,782 kg)
Max. takeoff weight: 6,500 lb (2,948 kg)
Powerplant: 2 × Lycoming TIO-540-A air-cooled six-cylinder horizontally opposed piston engine, 310 hp (231 kW) each
Propellers: Two or three blade, metal, fully feathering, Hartzell propeller
Performance

Never exceed speed: 236 knots[33] (438 km/h (272 mph))
Maximum speed: 227 knots (420 km/h (260 mph)) at 15,000 ft (4,600 m)
Cruise speed: 207 knots (383 km/h (238 mph)) econ cruise at 20,000 ft (6,100 m)
Stall speed: 63.5 knots (118 km/h (73 mph)) flaps down
Range: 1,011 nmi (1,875 km (1,165 mi))
Service ceiling: 26,300 ft (8,015 m)
Rate of climb: 1,445 ft/min (7.3 m/s)


From reading posts on a skydiving forum site the main concerns seem to be an overloading problem combined with an out of limits aft CofG which would have a severe detrimental effect on one engined flight and rudder controllability. That last comment comes from 2 pilots who fly Navajo parachute planes.
The one part of all this that horrifies me is that the occupants seemed to have survived the impact (this frequently happens in parachute planes where everyone is squeezed in tightly together) but then subsequently were burned alive. I've had to stand back and watch this helplessly on one occasion in my ambulance service life and I NEVER want to have to see or hear that again. That experience haunts me and was what prompted my last post.
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Old 07-12-2014, 10:35 AM   #20
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Very sad.

Comment though: Can we please be careful with the way we use words like overloaded.

As has been pointed out, 12 people on a Navajo is not necessarily 'overloaded' (5 to 7 people in seats is a very different operation to a jump operation). It isn't necessarily 'overweight', nor is it necessarily 'outside the CofG limits'. It may be one or more of these things, but just because there are 12 people doesn't have to make it so.

An engine failure in an aeroplane like a Navajo may not be successfully resolved well within its limits of performance. That is the nature of this sort of aircraft.

This isn't regular public transport, and there are significant risks in jump operations no matter how careful you are. Jumpers should be aware of this.

That doesn't change the fact it is always very sad when there is loss of life in an aircraft accident.
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