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TB10 HB-EZW down near Lucerne

lmsl1967 wrote:

Could 10 or 20 kg above MTOW create a critical situation leading to such sad end?

No. It could make a difficult weight situation a bit worse.

EGTK Oxford

The MTOW figure is determined, among other things, by slow speed performance requirements e.g. control surface authority at Vs, so 10-20kg extra at cruise speed is irrelevant.

But maybe they were not at cruise speed…

Another possibility is structural or control failure, as rare as these are on certified aircraft.

Administrator
Shoreham EGKA, United Kingdom

Many of us will remember seeing a friend of ours and his wife take off in a lowish powered aircraft (Jodel? I forget) from Chateau la Chassagne in scorching heat a few years ago.

We watched as he struggled to get airborne between the trees at the end of the runway and then disappeared from view. We just waited, appalled, for the bang and the smoke. We waited and waited and eventually saw them way below us in the valley skimming the trees and eventually climbing slowly towards Dijon. It was a very strong reminder to all of us that hot and high is a lethal combination. The rest of the party then decided to wait until the heat of the day subsided.

We knew in advance that the temperature was going to be above 40°C, and that the airfield sits at 1100’. It was interesting to note that of the about thirty who went on that fly out, only two were professional pilots. Those were the very two who decided to go to Dijon and hire a car.

EGKB Biggin Hill

I looked up Chateau la Chassagne and apart from having closed some years ago it is grass, and there are no performance charts for grass, for most GA types including the TBs – unsurprisingly, since there is grass and there is grass…

Kaegiswil LSPG is a hard runway of a known size and for the TB there are performance charts for tarmac. These are no rocket science – example for the TB20.

How far from LSPG is the crash site and what is its relative elevation?

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

there are no performance charts for grass

That wasn’t really the point.

He did get off the ground (the grass was actually very good, and anyway baked hard in the heat) but then disappeared out of sight well below the elevation of the airfield. The next time we saw him he was coming back the other way down the valley, at least 300’, possibly more, beneath us.

EGKB Biggin Hill

The MTOW figure is determined, among other things, by slow speed performance requirements e.g. control surface authority at Vs, so 10-20kg extra at cruise speed is irrelevant.
But maybe they were not at cruise speed…
Another possibility is structural or control failure, as rare as these are on certified aircraft.

TB 10 MTOW is 1,150 kg, with an empty weight of 730 kg, 2 adults and 2 kids, around 200 kg, it leaves 120 kg for fuel which is 45 USG. On such conditions is not difficult to T/O with 10 to 20 kg overweight.

Last Edited by lmsl1967 at 06 Aug 05:18
LPSR, Portugal

Peter wrote:

How far from LSPG is the crash site and what is its relative elevation?

In a straight line 5.5 km (3 NM). The pass is at roughly 3200 ft, so to pass over it would have required 3700 ft MSL, the airfield elevation is 1525 ft. That is 2’200 ft they would have had to climb. Density Altitude at LSPG was around 3300 ft.

The plane was occupied with two adults and two children plus baggage. Not sure where they wanted to fly to, it was said to France, but I would not think he was necessarily at MTOW.

LSZH, Switzerland

Mooney_Driver wrote:

Peter wrote:
How far from LSPG is the crash site and what is its relative elevation?
In a straight line 5.5 km (3 NM). The pass is at roughly 3200 ft, so to pass over it would have required 3700 ft MSL, the airfield elevation is 1525 ft. That is 2’200 ft they would have had to climb. Density Altitude at LSPG was around 3300 ft.
The plane was occupied with two adults and two children plus baggage. Not sure where they wanted to fly to, it was said to France, but I would not think he was necessarily at MTOW.

We are now talking at 700 fpm on a full loaded and underpowered aircraft, not a cruising mode where M&B becomes less relevant.

LPSR, Portugal

Unless you lean the mixture properly for take-off hot and high, you will be even more underpowered. Many flat-land pilots under-use the mixture control.

EBKT

Would you lean a TB10 for a 1525ft airfield elevation departure?

I don’t think this is a departure density altitude issue because they flew 3nm. They may have hit the ground because they could not climb (2200ft up over 3nm is some going) but it isn’t a simple departure issue. Especially in VMC where you can see clearly whether you will or won’t make it over terrain ahead.

Administrator
Shoreham EGKA, United Kingdom
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