Not quite the case -
deferred revenue will appear immediately, but that's a liability. Under
cash accounting the revenue would occur right away, but under accrual accounting you book revenue only once you have satisfied the performance obligations -- in this case, providing the flight (or reaching a point at which you
know the flight won't be taken -- ie after the customer has missed it).
david_oz's post provides a nice potential explanation, IMO, as to what they
could be doing...I sort of buy the potential earnings smoothing explanation, but the puzzling thing is that quarterly reporting isn't as big a deal in Europe as it is in the US. Note that IAG, for example, publishes
annual reports both for IAG as a whole and for each individual airline (BA, IB, VY, EI), but their
quarterly reports are quite short (for example Q3 2017 was just 7 pages!) and just at the consolidated IAG level.
That said, a lot of the tickets booked were probably for 2018 -- maybe IB is more generally worried about 2018 and is trying to smooth across 2017 and 2018? Like
david_oz I have no idea about the materiality of the Avios "sold" or the volume of tickets booked through this promo though.