Predictably, the media have picked up on the story and are misinterpreting the results (for which they can hardly be blamed, given the way they were presented).
From (I think) the Times, via Tw*tter:
No, entries 44-50 in Heathrow's list are
not the "noisiest airlines"
Among the airlines that serve Heathrow regularly, but don't appear in the list at all, are several with elderly, high-QC (i.e. noisy) types in their fleets, and at least one of the missing airlines clocked up a red-flag "pre-0600" infringement during those three months.
Nice idea, poorly executed ...