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Comment by wilkskyes | Hacker News Reader

Is it true that when the magnetic field flips suddenly, plane autopilot systems can become confused and crash out of the skies, killing millions en mass?

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That would be surprising as the altitude control should be independent from the compass. I'd also wager that more than just the compass is used to determine course. Most likely a sanity check in the control software will kick in and return control to the pilot, just as if the compass(es) broke for some reason during flight.

Primary heading indication is the directional gyro[0] anyway.

And magnetic flips don't happen "suddenly" in the timescale of a plane flight.

[0] https://en.wikipedia.org/wiki/Heading_indicator

How fast are the flips. I've known about this effect for maybe a couple of decades, but never heard any theories on how fast the flip is.

If the flip is really slow, then that seems to lead to less human catastrophe, but more difficult perhaps for other species?

edit: s/far/fast

The problem with the flips is that they go hand-in-hand with a dramatic weakening of the magnetic field until the new orientation is established. During that time solar storms are not deflected as well and vulnerable electronics will be fried.

If my new tv gets fried during the apocalypse I'm going to be pissed.

IANAPilot, but I got curious once upon a time and studied those. Short answer: yes, they will get confused, but they won't crash out of the skies. Those systems are designed to account for certain perturbations in magnetic fields. However, there are thresholds in place to return control to the pilot if the entire system craps out at that level.

I'd wager that magnetic compasses have faults from time to time and generally don't cause planes to drop out of the sky.

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