Does flying coach increase your chance of dvt?

Sometimes: The term "economy flight syndrome" refers to a DVT ocurring when remaining seated in cramped coach seats during long flights. Although rare, this can occur in people with a high risk of dvt. The simplest preventions are calf exercises while sitting and walking periodically. In rare cases, a blood thinner can be prescribed for use prior to flying. Aspirin has not been shown to decrease DVT risk.

Possibly: As dr. Roth said, immobility is the issue. It is easier to move if you have an aisle seat and much easier to move if you aren't flying coach.