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Comment by Rygian | Hacker News Reader

I'll ask the obvious: wouldn't the aircraft just take to the skies directly, without bothering with the formality of setting their transponder, if they were knowingly escaping an apocalypse scenario?

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There’s no formality. For planes with ADS-B out, it’s on when the plane is on (barring it being explicitly disabled by yanking the fuse).

Plus transponders are really convenient when you’re trying not to crash into other air traffic. Particularly in a scenario where you might be expecting ATC to be unavailable or abandoning their posts.

AFAIK the transponder kind of turns itself on when powering on the plane, you'd have to explicitly disable it but then you'd have weird discussions with the airport tower guiding you to a free timeslot on the runway which would just delay your takeoff, since ignoring the airport tower is a good way to not get off the ground at all because you'll accidentally be hit by some other plane.

99.99% of airports do not have "timeslots on the runway." Most airports in the US have no tower whatsoever.

But I bet if you filter for airports that business jets park at, the percentage of airports without towers is much lower than the overall average.

And the percentage of airports with "timeslots on the runway" is still going to be 0.

In a theoretical scenario of the billionaire class of the world having some kind of "advance warning" of the apocalypse, they'd be taking to the air in the hours or several days prior to a total disaster happening. Meaning this would be done while the local governments were ostensibly still functioning, in which case you can't just have your private jet depart without active ADS-B and in-the-clear voice traffic for ground, and air traffic control coordination.

If governments and airspace control have already collapsed, post tense, then of course anything goes.

Colliding with other planes is going to impede your escape plan, so it would still be a good idea to turn the thing on. No further action needs to be taken for the ADS-B output to be correct, it works once it's powered on.

Don't want to get shot down?

You won’t get shot down for merely taking off without a transponder.

Worst case scenario a fighter jet will be scrambled to investigate.

But in apocalypse scenario, chances are the fighter jets will be busy with tasks other than enforcing FAA rules.

> But in apocalypse scenario, chances are the fighter jets will be busy with tasks other than enforcing FAA rules.

Depending on the type of event, they very well could be scrambling to shoot down unidentified aircraft.

Fog of war sucks, and friendly fire still happens often.

They wouldn't have to set anything. The transponder on almost any modern plane defaults to automatically on, either immediately or at takeoff. With Mode C (reporting altitude) or S (& reporting more) and squawking 1200 (VFR).

If they have 5 minutes, sure. If they have 5 hours, they'll follow procedure.

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