Why the Learjet 60 Crash Left a Crater in Greenacres, Florida

This jet hit the ground so hard it left a crater in the road.

Why? Let's do the math. On the first of November, twenty twenty-six, a Learjet 60 fell from about ten thousand seven hundred meters over Greenacres, Florida.

Nine people were on board. In its last thirteen seconds, the ADS-B data shows it dropping about two hundred fifty-one meters every second, while moving forward at about one hundred twenty-three meters per second.

Join those two arrows with Pythagoras, and the speed is about two hundred eighty meters per second.

That's over one thousand kilometers an hour, diving at about sixty-four degrees.

A normal landing touches down at about three meters per second downward.

This was about eighty-four times faster, and the energy doesn't grow with speed, it grows with speed squared.

Kinetic energy is one half MV squared. The exact mass isn't published, so we estimate about nine tons.

Half of nine thousand times two hundred eighty squared is about three hundred fifty million joules.

That's like six hundred cars hitting a wall at one hundred kilometers an hour, all at the same moment, in one spot.

So how fast does it stop? The jet is about eighteen meters long.

Crushing into the ground, it stops in roughly that distance.

Deceleration is V squared over two D, about two thousand two hundred meters per second squared.

That's more than two hundred twenty G. The whole stop takes about zero point one three seconds, faster than a blink.

Force is mass times acceleration, about twenty million newtons.

That's the weight of two thousand tons pushed into about three square meters.

So the pressure is about six point five million pascals.

Sandy ground under a road is usually designed for only a few hundred thousand.

That's around twenty to thirty times too much.

The ground fails. Soil is pushed down and sideways, the road breaks apart, and a crater opens.

In South Florida, groundwater is close to the surface, and reports said water was found in the crater.

At these forces, a thin aluminum airframe breaks into small pieces.

As one Learjet captain explained, the energy transfer breaks apart the fuselage.

That's why so little wreckage was visible, and part of the tail was found up to six kilometers away, a sign the jet began to break up before impact.

Speed squared, huge energy, a tiny stopping distance, and a pressure the ground can't hold: that's the crater.

The cause of this crash has not been determined.

The NTSB is investigating, and these numbers are our own estimates.

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In memory of the nine people on board.