Each month, the three global carriers seem to reach new milestones in their efforts to improve operational efficiency, but one metric stood out in the latest figures released by the Bureau of Transportation Statistics.

In October, for the third month in a row, Delta (DAL) - Get Report was first in on-time arrivals, according to BTS numbers released on Monday. Even more rare was that Hawaiian (HA) - Get Report didn't finish first in any of the three months.

Three airline industry insiders said they couldn't recall a time when Hawaiian was beaten three months in a row by another carrier. "It's the first time at least in anyone's recent memory," said Delta spokesman Morgan Durrant. The Transportation Department began tracking airlines' on-time arrivals in 1987.

In recent years, Hawaiian has almost always been first. This is well-known in the airline industry because each month Hawaiian issues a press release, announcing its standing. Hawaiian Airlines benefits from operating primarily at Hawaiian airports, which aren't congested and generally enjoy good weather.

On Monday, Hawaiian's press release said the carrier "has reclaimed a top spot among the nation's carriers for on-time performance for October 2015."

In October, Delta was first among the 13 largest carriers with 92.09% of all flights arriving within 14 minutes of schedule. Hawaiian was second with 90.74% on time. The average for all carriers was 86.97%.

In September, Delta was first with 90.5% of all flights arriving on time. Alaska was second with 88.7%. The average was 86.5%. Hawaiian was 11th with 84.2%.

In August, Delta was first with on-time arrivals at 85.5%. Alaska was second at 82.9%. Hawaiian was third at 81.5%. The average was 80.3%.

In August, "multiple external factors impacted our on-time performance, including changes in air traffic control procedures, congestion due to airport construction and increased passenger traffic, and numerous weather events including lightning," said Hawaiian spokesperson Alex DaSilva.

"We have since adjusted our operations to mitigate these challenges, and we are pleased that our punctuality numbers have rebounded," DaSilva said.

In September, Hawaiian was hurt by its operational performance at mainland U.S. airports. At Portland International Airport, flights arrived on time 57% of the time. In San Diego, 63% of its flights arrived on time. At New York Kennedy, it had a 67% on-time performance.

In October, United (UAL) - Get Report also continued a pattern of operational improvement, finishing sixth among the 13 carriers with an 87.6% on-time performance. "We improved by more than 10 points over our October 2014 number (77.4%) and this marks our fourth consecutive month of improved on-time performance," said spokesman Charles Hobart.

This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.