The weighted average for May's on-time performance for North American carriers increased by 1.3 percentage points month over month to 79.3 percent, however performance of five of the 10 reporting airlines declined, according to the latest monthly report from aviation analytics company Cirium.
WestJet topped the May report with an on-time performance of 85.9 percent, a 3.1 percentage point increase from April. The carrier with the month's most-improved average was JetBlue, up 5.5 percentage points to 82 percent, putting it in fourth place, up from sixth in April.
Despite retaining its second-place ranking, Delta Air Lines' May on-time performance slipped 1.5 percentage points to 82.7 percent, while third-place Alaska Airlines had a 3.2 percentage-point decline to 82.3 percent. Southwest Airlines had the steepest drop, of 5.2 percentage points to 70.4 percent, putting it last.
The other carriers with month-over-month declines were United Airlines and American Airlines.
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WestJet was the only North American carrier to make Cirium's list of global on-time airlines at seventh. Saudia topped that list at 90.1 percent.
JetBlue had May's highest completion factor at 99.8 percent, followed by United at 99.4 percent and Alaska at 99.2 percent.
The number of North American flights canceled in May was 10,309 compared with 7,718 in April.
A flight is considered on time if the aircraft arrives at the gate within 15 minutes of its scheduled arrival time.
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