One step beyond rail replacement buses ... from
Business InsiderUnited and American Airlines are replacing planes with buses on some routes in an attempt to tackle the pilot shortage, a report says
Isn't that quite common, where a plane is diverted? Passengers are typically put on coaches to complete their journey, for example from Stansted to Birmingham. That's done on a flight by flight basis, though if the fog persists it could affect much of a day.
Would that be done for a planned closure of an airport? I'm sure it would, at least by Ryanair. After all, it's how they replace the bit of the flight that would get you to your destination city.
It might be more newsworthy if it was the other way round - a bus replaced by air travel. I suspect that has happened, probably in the USA, though I can't imagine why. And air replacement of rail must be quite common, if only for the kind of luxury tourist multi-day train trips we don't have here. And of course it would often provide the reverse leg to make a round trip of one of those, though you probably would not call that a rail replacement 'plane.