More flights may be landing late than major airlines admit, a new Department of Transportation inspector general's report says.

The office found no evidence that airlines are deliberately under-reporting late flights. But airlines that manually record what time flights land could manipulate that information more easily than airlines using an automated system, Inspector General Kenneth Mead says.

Mead found an unusually high number of Southwest and Continental flights reported as arriving 14 minutes behind schedule. Flights aren't counted late unless they're 15 minutes or more behind schedule.

''If you want to be on time, one minute makes all the difference,'' Mead says.

Mead launched an investigation in October after some airlines complained that Southwest and Continental were giving the DOT false arrival data. Southwest has the best record for on-time arrivals for the past 10 years. Continental ranks seventh of 10.

The DOT reports on-time statistics monthly for major U.S. carriers. Airlines on top use it as a marketing tool. Late arrivals are a major complaint of business travelers.

Mead's office observed arrival times of 372 flights at eight airports in January and checked those against data carriers reported to the DOT.

Ten airlines were checked. American, United, Northwest, and US Airways use an automated system. Southwest, America West and Alaska employees manually record arrival times. Continental, Delta and TWA use a mix of the two.

Some major airlines say that carriers who use a manual system cheat. ''We think there are carriers that are not being fully honest,'' says American's John Hotard.

Mead's office also found that 60% of flights that used an automated system recorded arrival times matching those it observed. But 41% of flights using manual systems had times matching those Mead's employees wrote down.

''Our reporting is accurate,'' says Southwest spokesman Ed Stewart. ''Some of our competitors want us to put in systems that will drive up our costs.''

An automated system costs about $60,000 a plane.

Continental says 98% of its U.S. fleet is equipped with an automated system, so manipulation would be difficult. It says many of its flights were recorded at the 14-minute mark because it has pushed to get flights in on time.

Mead is recommending that the DOT note in its monthly report which carriers use automated reporting systems and which ones are manual.

By Donna Rosato, USA TODAY

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