B737 Waterbomber crashes in south of W.A. Both pilots said to be not seriously injured but in hospital.

[tgh]

Good opportunity to post this…

 

[jb747]

Could you elaborate on the technical term 'mushed', please jb? I'm guessing you mean a pancake encounter with terrain, as opposed to a violent steep impact?

Well, it's obviously not a technical term, though I expect every pilot knows what it means. Basically very slow, bordering on the stall, but with minimal rate of descent. Not far off where the aircraft is when landing, though even slower. Explains the survivability. Very little vertical speed to do nasty things, and the forward speed is only 200 kph (!), so as long as you don't hit anything really solid....

What did they do wrong? To what degree did it appear to be poor aviating?

As always, it's a combination of things. For whatever reason, the aircraft has been allowed to become far too slow. The engines are spooled down to flight idle, and take a number of seconds to accelerate. So, when they've realised they're too low and slow, the engines don't respond quickly. No speed to trade off... I don't know how the 737 would behave with gear up and landing flap selected, but generally once you get to a landing configuration, the minimum idle increases substantially, to help avoid the power lag as you wait for engines to respond.

 

[JohnM]

Just in case anyone missed the link to the animation, including an instruments emulation at the critical time: ATSB preliminary report details 737 large air tanker accident sequence of events | ATSB

 

[JohnM]

Juan Browne has just covered it:

 

[JohnM]

Bumping this thread.

I was at Fitzgerald River NP last week. Unlike last year when I was there shortly after the crash, Hamersley Drive, the main dirt road running SE-NW through the park was open. This then allowed access to the 4WD track that leads to Quoin Head.

The gate is where the dirt section of Hamersley Drive begins, just beyond the bitumen and the turn to the Hamersley Inlet campground and picnic area. That was firmly locked last year as the crash cleanup was in progress.



Recalling what the crash site looked like.



Current Google Earth views.



Zooming in, the path of the aircraft can clearly be seen with SE direction of travel.

When on the ground last week, the large swath of bulldozed vegetation than ran either side of the 4WD track had me puzzled. It’s evident from the satellite view that ground crews, for whatever reason, carried out that operation. Perhaps it was a firebreak during wreckage recovery operations, which presumably would have involved considerable manpower and machinery?



Anyway, that’s all a prelude to some photos taken on the ground.

Facing SW, this gives some idea of the gentle downward slope to the S and the area where the aircraft came to rest on the left. Perhaps @jb747 could enlighten us as to what effect the aircraft flopping onto a gentle downward slope had, as opposed to impacting upward-sloping terrain?



Then the impact path on the right, showing the slope and type of vegetation. It was a very bright day, so the backlight didn’t help. I probably should have used my phone instead of my camera.



Then, facing in the opposite direction on the way back out from the drive to Quoin Head, the bulldozed break in the vegetation.

 

[jb747]

A downhill slope reduces the effective sink rate, making the impact a bit more gentle, and survivable.

 

[JohnM]

A downhill slope reduces the effective sink rate, making the impact a bit more gentle, and survivable.

That's what I intrinsically thought would be the case.

It would seem that luck was on the side of those guys - gentle downhill slope, no tall big-trunked trees, sandy substrate, cushioning vegetation only reaching about as high as the top of the aircraft.