After a surprise investigation of luggage scales at Phoenix’s Sky Harbor International Airport on Friday, the Arizona Department of Weights and Measures discovered a total of 31 violations among 72 scales.

The investigations in Terminal 4 were launched after a complaint from a U.S. Airways passenger, and government officials found that most of the violations were very minor.

Having accurate luggage scales is increasingly important to consumers, as airlines get more serious about enforcing excess weight fees.

Most airlines charge between $25 and $100 to check a bag over 50 pounds on a domestic flight.

The three scales which received the most serious red tag violations were part of Southwest’s operations. The others were at US Airways counters, which received yellow tag violations on 25 of its 46 scales.

The three red-tagged Southwest scales were not calibrated properly and started below zero. Though the underreporting error would work in customers’ favor, the DWM said it was still indicative of a faulty scale and needed to be fixed. The other problems were relatively small and included issues such as digital readouts not working properly.

The DWM ordinarily inspects airport scales once or twice a year, but it has fallen behind recently because its attention has been diverted to checking gasoline pumps. With the spike in gas prices last summer, complaints about possibly faulty pumps tripled.

Both Southwest and US Airways pledged to have their respective scales fixed and back in action in a matter of hours. A spokesman for the DWM said that more inspections were planned for the other terminals at Sky Harbor airport, probably after the holidays.

Related links: USA Today, Arizona Daily Star, NBC 12 News

By Karen Elowitt for PeterGreenberg.com.

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