Just looking at flight times of some European airlines, you can see that they all arrive Tehran really late at night/very early in the morning. Why is this? Why no daytime flights? Is this a 'co-incidence', or just what makes the most sense for the airlines? Or does it have any political reasons?
Some examples are:
KLM from AMS: KL433 arriving at 3:30am
Lufthansa from FRA: LH600 arriving at 01:30am
Alitalia from FCO: AZ756 arriving at 04:05am
Austrian from VIE: OZ871 arriving at 03:00am
Aeroflot from SVO: SU512 arriving at 02:45am
Not sure what flight times Iranian operators use, but it seems like the European airlines flying to Tehran all have the same pattern.