The Transportation Department said complaints went up, anyway.
The department said the two flights that kept passengers held in planes for long delays on the tarmac included American Airlines Flight 181 from New York's John F. Kennedy airport to Los Angeles and a China Airlines from Taipei, Taiwan, to Los Angeles, which was held on the tarmac for 4 1/2 hours. Both incidents occurred Nov. 30.
The department said the planes were delayed by severe storms in Los Angeles that day, but both delays were under investigation.
For domestic flights, the department requires airlines report any tarmac delays longer than 3 hours. For international flights, a 4-hour or more delay must be reported. Airlines face fines for holding passengers in planes for longer than the 3- and 4-hour limits.
In November, on time rates improved compared with October.
Among the 16 largest U.S. airlines, the on-time arrival rate was 85.3 percent, compared with 83.2 percent in October.
That didn't stop passengers from complaining. The Transportation Department fielded 873 complaints in November, a 30.7 percent increase from November 2010 and a 1.3 percent increase over the previous month.