Airlines make a lot on 3 industries

There's some simple math when it comes to airfares - the higher the price, the bigger the profit.

And the most expensive tickets tend to be those sold at the very last minute-specifically those picked up by business travelers with schedules dictated by sudden deals and unexpected client meetings. And not coincidentally, these fares are usually paid for by the company.

It also turns out there are some marked differences in buying habits among industries, according to data released Thursday by Concur Technologies, which analyzed 25 million airline ticket sales last year across nine industries. Perhaps unsurprisingly, professional service fields, such as lawyers and consultants, bought more than a quarter of their air tickets within three days of a trip, the largest segment.

Media was next, at 20 percent as news events often tend to erupt without warning.

At the other end of the spectrum is higher education, with 68 percent of tickets in that field being sold 15 or more days before a trip.

Industries such as energy, financial services, manufacturing and technology fell in the middle of the spending pack.

Airline tickets booked less than a week before departure are 44 percent more expensive, on average, than the same ticket booked 15 or more days in advance, according to Concur, which sells corporate travel and expense-reporting services.