My original post was badly written and not quite I had meant to say. I didn’t intend to imply that particular airlines use a misleading way of using arrival times. But I did mean that airlines in general might be happy if the “system” suggests better arrival timekeeping than is actually the case.
Here is the sort of misleading confusion I had in mind.
From the Gatwick Live Arrivals
08:30 BA2262 KINGSTON EXPECTED 08:32
08:30 was the scheduled time to be on blocks. But the expected 08:32 was the ETA for landing.
(In fact one and a half holds were needed; it actually landed at around 08:38. That could hardly have been fed into the landing estimate so not complaining on that score.)
However the implication was that the flight was expected to be just 2 minutes late which was never going to be true. For the live arrival board to quote – and invite comparison – between two different things is misleading: it is not comparing like with like. If touchdown was expected to be 08:32, then it would have been far nearer the truth to say EXPECTED 8:40. This would therefore compare expected blocks time with scheduled blocks time.
(I accept that landing-to-blocks interval is a huge guess)