Why is this video of a G36 Bonanza so 'scary'?
If they had clipped the top of the trees, would it really have brought the plane down? (And even if yes, it looks pretty survivable).
If you look at this document regarding the Bonanza G36 performance you will note that the lowest stall speed written is 61 kts. 61 kts is 112 kph or 71 mph. We can assume they were going a little bit faster than that but let us say 110 kph / 70 mph.
In that clip, they are just barely keeping airborne. This means the aircraft is extremely sensitive to disruptions. Any loss of power — even partial — or getting knocked back by a collision and thus losing a few knots or upsetting the aerodynamics of the aircraft, is very likely to send it crashing into the trees.
Going 110 kph / 70 mph into a tree is rarely survivable even in a car, and then you have to remember that cars these days are built to withstand crashes while at least keeping the occupants alive, but that assumes crashing into something wide, that distributes the forces over a wide area, and that gives way, like another car. Trees fail that on both accounts.
A G36 does not even come close to any such structural integrity in case of a crash. The cabin will crumple like figurative tin foil, sending the occupants smashing into the trunks of the trees, or throwing them clear of the aircraft only to then smack into other trees or the ground from several meters up and at a high speed. And that is going to be fatal.
Hence, this is scary because if they clip a tree they are very likely to die.
They Trimmed the Margins to Zero
In this video, the aircraft takes off and flies a straight course through the trees and continues a shallow climb out. To the uninitiated, this may appear innocuous, until one realizes that the aircraft was performing at it's maximum limits with near zero room for error.
The voice and narration of this video does a good job breaking down what happened in this scenario, to recap in writing:
The pilots appear to have calculated the takeoff performance, found it to be adequate and made their attempt. Their calculations were likely correct, but sufficiently lacking in margin so as to excite those on board who were cognizant of the situation.
It is reasonable to assume that aircraft performance tables are generated under near ideal and non-threatening conditions.
It is also reasonble to assume that:
A pilot who flies recreationally may not be able to squeeze every bit of rated performance out of their aircraft.
Mistakes can be made in the calculation of weight and balance which affect performance.
Conditions may change between the time calculations are made and time of takeoff.
Near the end of the commentary, the pilots can be heard verbalizing their learning experience. I think the lessons of the experience are not lost on them.
Lessons of aircraft performance are somewhat frightening to me as an aspiring instructor. Training usually occurs at one airport, often with a long runway, with one aircraft or type of aircraft and one loading scenario. If the training is compressed into a few months, the student may not even be exposed to a significant range of weather conditions.
I intend to teach my students to be awake to the amount of runway they are using and load the aircraft in multiple configurations as part of the training. I think many pilots have a moment of nervous surprise the first time they experience narrowing margins. I would like it to be less of a surprise.
Learn from this video, and from this other one, which had a less fortunate ending:
What makes it scary is just how close they did come to an accident. They attempted a takeoff using the performance calculations listed in the POH on a hot day at high field elevation. That’s fine assuming EVERYTHING works out just like the book ie no errors in calculating performance, aircraft and engine in peak condition, field atmospherics, perfect short field takeoff technique, etc. But as the video showed, they came damned close to clipping the tree tops on climbout.
The aircraft in question was a turbonormalized G36 departing from Mears Airport (3W5) in Concrete, Washington. The small country airport is located in a river valley surrounded by mountains. According to the pilot the performance calculations show that the aircraft could do it, and so he attempted to try it. Fortunately he managed to weave his way through the trees at just under stall speed to get clear of obstacles and clean up and accelerate the aircraft out of the reverse side of the power curve. The film is scary because it shows just how close he came to having a controlled flight into terrain or striking obstacles. Mountainous terrain quite often has downdrafts coming through the valleys on the windward side. Had he encountered one, he would have never made it.
The airport is built on a small flat land surrounded by rough terrain. Had a pilot collided with the treestops at the end of the runway, there was a good chance that he would have lost control and crashed. The likelihood of survival in a situation like that, particularly in a high-performance airplane like a bonanza climbing out at 80+ knots, is not great.