The across-the-board rate for all airlines flying to the airport fell to 67 percent, bad enough to rank Salt Lake City 27 of 32 major U.S. airports, the federal government said Monday. A year ago, when the weather was better, the arrival rate was 82 percent.

"It would be linked to the inversion," airport spokeswoman Barbara Gann said.

Normally, Salt Lake ranks at the top of the on-time list of big airports tracked by the government. Last year, 83.5 percent of all flights landed on schedule. But the January inversion produced an unusual number of heavy-fog episodes that compelled controllers to put more space between aircraft in order to avoid collisions.

"Inversion factored into performance in January and February," Delta Air Lines spokesman Anthony Black said.

Delta's on-time rate of 79 percent led all airlines serving Salt Lake City. But SkyWest Airlines, which flies for Delta as Delta Connection and lands more flights in Salt Lake City than any other carrier, turned in one of the worst performances. Only 65 percent of St. George-based SkyWest's 6,957 arriving flights reached the airport on schedule.

SkyWest officials were unavailable for comment Monday.

Atlantic Southeast Airlines, which also flies for Delta and is SkyWest's Atlanta-based sister company, did worse. Just 54 percent of its flights to Salt Lake landed on time.

Visibility was unusually bad in January, said Larry Dunn, meteorologist-in-charge for the National Weather Service in Salt Lake

"We had 25 days of fog, and 10 of those were dense fog, with visibility a quarter-mile or less. That's a pretty foggy month," Dunn said. Visibility on a typical day is 10 miles or more, he said.

Southwest Airlines spokeswoman Marilee McInnis said there were eight days when local controllers issued ground stops because of poor weather conditions. Each stop, when airplanes can't take off or land, lasted about 90 minutes, she said.

"Our delays in January were not extensive, but we did have 17 flights that were delayed more than two hours in January due to weather, air traffic control issues, and that sort of thing," McInnis said.

Nationally, SkyWest struggled to get its airplanes to their destinations on time. It flew almost 44,000 sorties during January, and 35 percent failed to arrive when they were expected. The performance was the worst of the 20 carriers tracked by the government.

SkyWest's performance was only slightly better than in December, when 64 percent of its flights landed on schedule.

In Salt Lake, 13 regularly scheduled SkyWest flights into the airport were delayed at least 80 percent of the time. Flight 4067, which flew from the Dallas-Ft. Worth airport 27 times in January, was late 100 percent of the time. The flight was late an average of 59 minutes, according to the government.

SkyWest also battled baggage handling problems. The company received 17.38 reports of bobbled bags per 1,000 passengers in January - the second-worst performance of all domestic airlines. The U.S. average was 8.19 reports per 1,000 passengers.