It appears that at around the 17 second mark of the video posted above, that the float(s) start to operate independently to the aircraft. At that point the aircraft has become laterally unstable and far less controllable.

Got a feeling you've hit the nail on the head, I haven't seen a lot of floatplane take-offs but there seems to be a lot more movement of the floats during the roll than I would expect and indeed at that 17-second mark the left float, in particular, seems to be moving a bit more. Certainly seems to be struggling after getting itself on the step and even after it looks to be skipping a lot, from what I understand they're meant to be pretty sturdy buggers but could that skipping have caused it to detach at least partially? Haven't seen anyone mention if it's normal for a no-flap takeoff in a floatplane but from my understanding, it isn't.

I didn't see anyone exit from the now underwater wreck.....Did they get out OK?

OOOpppsss... Just re-read #1

My “friend” seems to know a lot. Maybe he should start posting here.

From a glider pilot perspective* it looks as though at some point in the proceedings it becomes increasingly apparent that its going to be a near thing to clear the terrain ahead, so there's a gradual deviation to the right. That was working, but just on a lift off (drag off) there is a slight left wing drop which is countered by increasing opposite right aileron going to full deflection. Intuitive perhaps, but wrong in this unusual sequence of events. At low speeds at or near near the stall this is a set up for an incipient spin which is exactly what happened. Ailerons neutral and a generous but short boot of right rudder at the point where wing drop was sensed may have salvaged the day .... I am still not sure whether the aircraft was really ready to fly at that point however.

* Dropping a wing on ground run in gliding is a known (if occasional) occurrence. Accordingly we train for it, and it can be salvaged in almost all instances - not by corrective aileron (the wing is probably still not at flying speed) but by a generous and brief application of opposite rudder. You need to be on the ball not to over correct, but that's what flying is all about - keeping ahead of the aircraft. It's a situation rarely encountered in powered aviation, so the concept is probably little known there - if at all.

Agree.

Certainly Captain. As all radar controllers will have observed the relative bearing was not changing so a meeting was inevitable unless one of them changed course.

Gne

The looming terra firma and the flora growing on it look to me to be a bigger risk to the aircraft.

I am of course only going on the video. But the left hand photo in post #2 places the capsized aircraft quite close to the shore, albeit after drifting for a while.

I am with 43”, Squawk & Ixixly: I also had feeling the floats started to move independently of the fuselage. Would put the pilot in a difficult position about what to do next if they realised that was happening. The struts were certainly getting a workout earlier in the takeoff run.

What to do next… What to do next…

I wasn’t there, but I’d set “THROTTLE” to “IDLE”.

I’m wondering if a flying wire broke on the floats. Just a thought that popped into my head for no apparent reason ;-)

Here is link to one such interview on Channel 7 News (hope link works):

https://www.google.com.au/url?sa=t&r...Ocl-i7rRO_Ivcg

Seaplane was VH-DAB, a Rans S-7S Courier according to AustAirData which has photo of it in better times.

Implication that the cause was component failure. Looks like our team of video analysts in earlier posts were correct.👍

There was indeed a component failure and the flight was still recoverable, however the Swiss cheese aligned and around 4 other detractors meant that the flight was doomed. As we often see with these things, it’s usually not just one thing alone that causes the outcome.

With floats throttle to idle can make it nose over as the airflow over the elevator is lost, to stop it flipping over from the floats digging in nose first you have to apply back pressure, which normally lets the back of the floats dig in and slow down. It's possible he did cut throttle kicked off a wave and became airborne unexpectedly with no power and just slumped back to the left and flipped anyway. Just a theory. From what I've seen of those S-7S with the 100Hp they seem to fly away quite well with the engine running. My take is that everything looked normal, it was on the step at close to flying speed early in the clip until just passed the pylon, then a porpoising wave action where it seemed to lose speed and maybe a float come loose, sudden veer right, cut throttle, pull back, becomes airborne off a wave and the rest is obvious.

At 1:30 into this news item from a few days ago they include a statement from an ATSB spokesperson:


"...pilot... detected a loud bang and observed damage to the right float which was partially detached. The pilot reduced power, and the left wing made contact with the water..."

It goes on to indicate ATSB will not be investigating the incident further.

That broken item is one of the swaged flying wires that keep the floats stable from side to side. It’s something you need to check in your pre-flight to ensure that it is correctly tensioned, especially when your aircraft is uninsured like this one was…

For my own armchair education (not being a float pilot - not yet, anyways) having just experienced "a loud bang and observed damage to the right float which was partially detached" .. Wouldn't you want to light the right float (as I'm assuming he did) but keep the power UP to get clear of the water ASAP? Surely there's a speed at which it's too dangerous not to continue??

The water conditions were tricky to start with, let alone continuing with a float doing it's own thing. You also have to think how broken the float is, if it hangs at some weird angle in flight then you will be uncontrollable most likely. Even if you did get airborne you are going to flip on landing anyway, I can't think of any way you will prevent that short of jettisoning both floats and belly landing somehow. Even if you can land on one float as you slow you will settle on the other quickly, there's no rudder at slow speed as the water rudders are retracted, and would do bugger all to counter strong yaw anyway. The best thing to do is cut throttle and try to stop, in reality the flip was probably a good outcome as everyone survived with minor injuries. Float planes are hard to insure for good reason, but I can say some of the best fun you can have with wings.... Luckily water is relatively soft at slow speed, so you can walk (swim) away from most mishaps on take-off or landing. The only downside is the restoration cost, which is why insurance looks the other way.