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Comment by crististm | Hacker News Reader

Can you differentiate between an aggressive maneuver that results in loss of consciousness and a similar maneuver followed by a controlled one that looks like flight into terrain but is not ?(e.g. because pilot does aggressive acrobatics). Or two aggressive maneuvers followed by almost level flight but where one of them is with loss of control.

I'm interested what would be the cues that can be taken from controllers and plane attitude that can make the software say something in the line of "this guy seems lost, I'd better pay more attention". Of course nose down is one, but what about more subtle ones?

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Assuming a G-loc'd pilot looses most or all muscle tone, a simple manual override for the GCAS could be a "grip strength sensor" in the stick.

That makes sense. Besides trajectory prediction, the software can assume something can go wrong if muscle tone decreases following a hard manoeuvre.

in principle the software could be forecasting an envelope of possible future trajectories of the aircraft given the current state. if we detect that we are about to commit to a state where our only remaining future options all involve colliding with terrain, we make an intervention.

From the fine article:

> Auto-GCAS continuously compares a prediction of the aircraft’s trajectory against a terrain profile generated from onboard terrain elevation data.

Yes, I think this is how it works.

> The [Aircraft Response Model] is a sophisticated simulation of the F-16, running at a real-time rate. "It's a fairly complicated algorithm that tracks fuel-burn, takes information from the stores management system [about weapons weight and drag], and even accounts for system processing delays," said Mark A. Skoog, USAF's AFTI F-16 test director. "Using the aircraft's current state, the ARM computes a full six-degree-of-freedom simulation during a roll to wings-level. At wings-level, [ARM switches] to a 2D-type recovery--a second-order modeling of the jet's pitch response. It calculates how much [kinetic] energy it can trade for altitude until the jet reaches a desired zoom-climb speed, then holds that speed." (http://www.f-16.net/f-16_versions_article8.html)

So the system continually computes the best trajectory for avoiding the ground, and takes over if that trajectory ever goes below the currently selected "minimum descent altitude". Pilots can adjust the MDA depending on how low they plan to fly.

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