This could be the biggest surprise of 2012: US air travel actually improved for passengers last year.

That’s according to a new ranking of US airlines released last Thursday by the Wall Street Journal (WSJ), using data from and the Department of Transportation, which oversees air and other transportation in the US.

The report ranked seven major airlines – Alaska Airlines, American, Delta, jetBlue, Southwest, United and US Airways – according to six criteria: late flights, cancelled flights, extreme delays, bumped passengers, lost bags and complaints. Top line findings: overall Delta was the best airline, while United was the worst.

The report also found “industry wide improvement” in air travel. Almost 80% of domestic flights were on time, or within 15 minutes of scheduled time, in 2012. (By contrast, 76% were on time in 2011.) Only 1.4% of domestic US flights were cancelled last year, compared with 2.1% in 2011. What’s more, fewer flights had excessive delays (defined as 45 minutes or more), and there were fewer lost bags. Nonetheless, the report notes that the frequency of bumping passengers increased, as did the overall rate of traveller complaints. Altogether, though, the data added up to friendlier skies in 2012.

Passengers on industry leader Delta enjoyed the lowest rate of cancellations, according to the ranking, and among the lowest rates of late flights, bumped passengers and lost bags. The top slot marked a significant turnaround for Delta, which came in last in the Journal’s 2010 ranking during its merger with Northwest. Since then, the airline has taken serious measures to improve its efficiency, including rebuilding its luggage system at its Atlanta hub to cut down on lost baggage, and analysing historical cancellation data to adjust the availability of spare aircraft in different hubs in order to keep flights moving.

Conversely, 2012 was a rough year for United, which came in last in the WSJ’s ranking (dropping from its second-to-last spot in 2011). The airline had the highest rate of bumped passengers in 2012, as well as the highest rate of customer complaints. In fact, United’s customer complaints were so numerous they accounted for virtually all the industry-wide increase in complaints in 2012. United received some 3,617 complaints in the first 10 months of 2012, compared with 958 during the same period in 2011. By contrast, Delta had 777.

Among the reasons for United’s dismal performance last year was its glitch-plagued merger with Continental. Critical data was lost during electronic transfer of United passenger information to Continental computer systems, leading to lost reservations, long phone wait times, late and cancelled flights and angry customers.

American performed similarly poorly, coming in second-to-last with the highest rates of late and cancelled flights. Contract disputes with pilots led to a slowdown in autumn flights that likely led to their high rates of late and cancelled flights.

The 2012 results:

  • Delta
  • Alaska
  • US Airways
  • Southwest
  • jetBlue
  • American
  • United