Try https://skyvector.com/.



You can input the departure/arrival airports and even the whole route if you know it and it should trace it out for you. I recommend switching to World-Hi map for long-haul flights. Flightaware seems to give full routes for flights to/from the USA, but perhaps not intra-Asia or Asia-EU. The above image is an actual route from UAL896 from HKG-ORD (VHHH-KORD). I think this is more what you are looking for maybe?

dan