alt Hacker NewsIf application engineers did their job correctly, they have nothing to update because you should store future events as a wall clock time + timezone, not an instant (ie something like `2026-09-01T09:00:00, America/Havana`, not `2026-09-01T09:00:00-05.00`).
Which means that flight booking systems are _probably_ fine (they're probably the domain that cares most about timezones and time changes so they've probably modelled it right), but many systems are not fine because it's such a common thing to get wrong.
But that is _exactly_ the problem.
Flights take x hours in the sky, and so would have left at `2026-10-01T09:00:00, America/Havana`, and arrives at Miami at `2026-10-01T10:25:00, America/Havana`.
Now, they have to choose, do they arrive at 10:25, and leave at 10:00? Or do they leave at 9:00, and arrive at 9:25, since only _one_ of those two timezones is changing. It is extraordinarily unlikely that they'll choose to just circle in the air for an hour so that they can just keep the same departure and arrival times.