CALGARY — WestJet reported May 2015 traffic results with a load factor of 77.2%, down 1.8 percentage points compared to May 2014.

Revenue passenger miles (RPMs), or traffic, increased 6.6% year-over-year, and capacity, measured in available seat miles (ASMs), grew 9.1% over the same period. The airline flew a record 1.6 million guests in May, a year-over-year increase of 3.9% or more than 63,000 additional guests, and achieved an on-time performance rate of 93.2%, a year-over-year improvement of 8.3 percentage points.