I want to know how much demand there is for OR in the commercial world, and understand the relevance and prevalence of OR.
Is the airline industry the place where this technique is applied the most? What other areas would OR be in demand from your experience?
Also, is it mainly academics that perform OR for corporates or are consulting firms providing this service as well?
Airlines do indeed rely on operations research. So does UPS, which has an in-house operations research group that has generated sizeable cost savings for them.
Rather than listing the various industries that use OR, I'll just recommend that you look at past winners of the INFORMS Franz Edelman Award. You might also want to look through a few issues of the INFORMS journal Interfaces, recently renamed the INFORMS Journal on Applied Analytics. Many of the articles in it document OR applications in industry.