Some companies won't pay a dime for interview traveling; their philosophy is if a person wants the job bad enough, they will find a way to get to the interview. Some companies will use it as a strike against you during the interview if you even bring the subject up of travel reimbursement.
While other companies, when they invite you to an interview will explain all of the travel arrangements in detail, pre-arrange and pre-book all of your travel, and give you instructions on how to get reimbursed for any additional travel expenses incurred.
I've interviewed with companies where I've spent more time on the phone and email discussing travel to/from the interview with the travel department, than I did with HR, hiring managers, and potential future bosses in the actual interview.
I've taken jobs where I got zero reimbursement for travel, and I've turned down jobs where the company spent over $1000 in airline tickets, hotel, food, and rental car for just the 1-2 hour interview. It varies from company to company, with the overall economy, and supply and demand of pilots.