An example of how limited air transport is can be seen in the amount of transport needed to get a battalion of Canadian infantry (the Princess Patricia Light Infantry) back from duty in Afghanistan. The U.S. Air Force had to life 780 troops and 1,350 tons of weapons and equipment. It took 24 flights by U.S. C-5 transports to accomplish this. The C-5 is the largest transport in U.S. service. Because Kandahar airport is still considered a combat zone, the C-5s kept their engines running while they were loaded. This reduced the time on the ground for the C-5s, and the risk of them getting shot at.