With capacity increasing 9% in the month of May, airline operator JetBlue (NASDAQ:JBLU) said today that its traffic jumped 9.4% from the year-ago period.

Per-seat passenger revenue was up 1%, which was in line with the airline operator's expectations of a 0% to 1% rise, while its load factor, or the utilization of total available capacity, was 85.1%, an incremental 0.3% increase from May 2012. It also noted its preliminary completion factor -- or the number of flights JetBlue completed in the month -- was 99.6%, while its on-time performance was 80.3% On-time performance is a Transportation Department measure of flights arriving within 14 minutes of its schedule. JetBlue's performance was better than that achieved in April, when fewer than three-quarters of its flights arrived on time.

Year to date, JetBlue has seen its revenue per passenger mile jump 7.3% over the same period last year while available seat miles were up 6.9% in the same time frame. It expects June's preliminary passenger revenue per available seat mile, or PRASM, to be flat year over year.

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