I became interested in ADS-B tracking through my enthusiasm with the Raspberry-Pi and a phone app.
Initially felt the instructions better on this site than FR24 plus I tend to prefer this forum. I also feed FR24.
Appreciate FA and FR24 are both commercial enterprises but am wondering about the non profit making volunteer sites such as Opensky-netwok.org and ADSBexchange, what is their purpose? They tend to mention storing and making available historic data, other than see how traffic has increased what is historic data used for? I’m doubting they are contacted regarding air incidents, or are they?