For sure it is an interesting site but it can't be showing all flights. For example I zoomed in on Austin Bergstrom in Texas (an airport I often fly into) and found zero flights going in or out and at 11.30am there should be a lot of movement. I would like to know if they include all airlines.
Chub_tor Yes I think you are right, if you take a look on the coverage tab at the top it explains how they go about getting the data and the limits. Seems to find most of the aircraft around the Wirral where I live, infact (I know it's sad), but I've been watching the site and listening in on my scanner and it's reasonably accurate ...alB