Peculiar definitions in an aviation world where there have long been security screening checks — general/originating passenger security screening checks, transfer passenger security screening checks, and gate-area passenger security screening checks — that can be placed before and after going through other passenger security screening checks to get to an aircraft on multi-flight trips.

They seem to define landside as necessarily being the non-sterile side of an airport and airside as being limited to just the sterile side of an airport. But:

1. airside ≠ sterile section of the airport; and

2. landside ≠ non-sterile section of the airport; and

3. there are also non-sterile, airside sections of airports.

Think about the four terms/sets — airside, landside, sterile and non-sterile — in terms of a Venn diagram.

And to throw in a loop, what about for those scheduled commercial passenger flights even post-9/11 where it’s been possible for passengers to fly without going through a passenger security screening checkpoints before the flight? Are the passengers landside throughout their trip by plane from airport to airport? By those peculiar definitions from Collins and Macmillan, such passengers would have remained “landside” for the entirety of the trip from airport to airport by air.

Do you consider yourself always “landside” at LHR whenever having previously done connection at LHR on say a AA+BA US-LHR-EU/India/Israel itinerary without physically clearing passport control with the UKBF (and/or predecessor agencies) at LHR? I certainly don’t, and those trips continue to have a passenger security rescreening involved during a connection.