We have 767-200ERs, with Nominal still-air range 5000 NM. why seat is limited for my routes BKK-FRA, BKK-FCO, BKK-AMS? These routes are all less than 5000NM.
I'd suggest doing a forum search for "range" and related topics.
Essentially the range listed for aircraft is "still air". But in the real world there are upper air currents, sometimes up to 100knots. That's why it's often 7 hours London -> New York and only 6 hours back. This is now modelled in AWS. Most people suggest taking 30% off the still air range as a rough guide.
Simon
Check out the manual: https://www.airwaysim.com/game/Manual/Aircraft/Performance/#Payload
Thank you for the infos.