Are we talking easyJet (known as the web's favourite airline) or Ryanair (which is)?
Assuming the latter:
2,140,000 pax per month = 71,000 a day (assuming bookings flow evenly)
71,000 a day = 2958 an hour
or about 500 in 10 minutes.
Average spend £40 = £20,000.
Almost an afternoon's pay...
If it's EZY, a few less pax, a bit higher revenue - the answer's close.