What happens if you check in online and then don’t turn up for the flight?

[MrsWicket]

I know this should be in the travel section, but posting here for traffic. Off on holiday with two friends - it’s now 50/50 one can go but they won’t know for sure until the morning of the flight. Obviously we’d like to sit together if we can when we check in. Does anything happen if the person is a no-show at the airport? Thanks

They assume you didn’t make it to the airport, because your boarding pass never gets scanned at security

Nothing will happen, no. They will just assume they've missed the flight for whatever reason (and the return will almost certainly be cancelled).

Ah, thanks for the replies. Hopefully friend can make it.

The return won't get cancelled immediately, there's some sort of practical grace period to allow late people to arrange a different flight etc. I've had to twice... both rearranged about an hour after we should have been on board. Sigh.