Try www.oag.com there is an option to view Airlines by Routes

Here are the results for HKG-BKK

<span style="font-family:Arial"><blockquote>The following airlines fly direct between Hong Kong (HKG) and Bangkok (BKK) on 30 November 2007

Code share flight - indicates some flights may be operated by another carrier

Airline Name Airline Code
Air Madagascar MD
Air New Zealand NZ
Cathay Pacific Airways CX
China Airlines CI
Emirates EK
Hong Kong Express Airways UO
One Two Go Airlines OG
Orient Thai Airlines OX
Pakistan International Airlines PK
SAS Scandinavian Airlines SK
Thai Airways International TG </blockquote></span>