Where do FR24 get their aircraft reg linked to scheduled future flight data?

[Peter47]

A very interesting area as I have been spending several hours trawling data from FR24 for some work I am doing trying (there must be a better way of accessing data but it would cost). They state

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I assume from the above that apart from the obvious source of transponders they access airline websites or possible their computer system directly. I believe that the Schiphol enthusiasts site uses a webcrawler.

I have generally found that info on passenger flights is much more accurate that than for cargo where there are often duplicate entries (a middle sector of a triangular flight may have the flight number of both the inbound & outbound sector) & Fed Ex & UPS can be hit or miss.

Errors I have found include:
The flight apparently operating from a by nearby airport. Have a look at flight UA1917 in 18th July (the day I was looking at). The Denver QQH - San Diego sector appears to be a wobbly.
- Diversions that appear not to have happened. Have a look at flight DL273 LIS - JFK - SFO on 8th Aug. The first sector apparently diverted to SFO but not according to the replay. - Obviously a glitch on the system.
- Getting the direction of the flight wrong (quite easy when inbound and outbound legs have the same number). An example DL1865 on 18th July. It shows two FLL - DTW sectors but the first one is actually the opposite direction (and the landing time is incorrect).

Unfortunately airline websites do not give historic data so I can't double check more than about 24 hours after the event. I used to use Flightstats to cross check but they now charge - I don't know if its worth taking out a subscription.

Its an interesting area and I'd love to hear from experts.