WestJet had the highest on-time performance (OTP) average among North American carriers for the fourth consecutive month in August at 82.6%, but it was down 1.3 percentage points from July’s average, according to the latest monthly report from Cirium, an aviation analytics provider.

Delta Air Lines had the second-best OTP for the month and saw the largest month-over-month increase at 4.2 percentage points for an on-time average of 79.2%. United Airlines was third at 74.5%, down 0.9 percentage point from July. 

Overall, North American carriers held steady compared with July, increasing 0.5 percentage point to a weighted average of 72.1%. Air Canada had the largest decline and was down 3.1 percentage points to an on-time average of 65.4%.

WestJet was the only North American carrier on Cirium’s August global list of on-time airlines at fifth. Aeromexico was first with an OTP of 89.7%.

Southwest Airlines had the highest August completion factor among North American carriers at 99.2%, followed by Alaska Airlines at 98.6% and United at 98.5%. 

The number of North American flight cancellations in August was 18,295 compared with 22,921 in July.

A flight is considered on time if the aircraft arrives at the gate within 15 minutes of its scheduled arrival time.