We recently flew DL49 AMS-JFK which was delayed by 3h10min on departure and a few minutes less on arrival at JFK. Reason was given as some auxiliary power generator problems.

Delta itself never brought up any possible delay compensation, although I think they should have. Their web page also seems to incorrectly state that a passenger may be entitled to compensation if "Your flight was delayed for more than 5 hours."

I looked at EC261/2004 delay rules (and checked the much longer thread in the BA forum) but remain confused. The rules look somewhat contradictory to me:

1. On EU passenger rights site it is stated that if the flight "arrives more than 3 hours late on arrival at the final destination stated on your ticket, you may be entitled to compensation".
2. In the AIR PASSENGER RIGHTS EU COMPLAINT FORM, however, the Long Delays are defined based on the departure delay, according to distance traveled. Which in the case of DL49 would imply delays >4h.

A wikipedia article suggests that the >3h on arrival was based on a few court cases.

I've read posts by a few other folks here who had positive experience with Delta honoring 261/2004 but also other negative experiences as well.

So my question is: which definition would apply to my DL49?