Michael Kaldenberg spends so much time flying that he likens himself to George Clooney's character in "Up in the Air."

As vice president of sales for Conair Corp., he flies between 175,000 and 200,000 miles a year, mostly using the Twin Cities as a hub from his home in the Green Bay, Wis., area. He's away from home about 260 days a year, and his frequent travels have won him the highest rating -- diamond medallion -- with Delta Air Lines' SkyMiles loyalty program.

Like Clooney's character, Ryan Bingham, Kaldenberg and other high-mileage travelers live for their first-class upgrades, which Kaldenberg got used to with Northwest Airlines, now part of Delta. "We're loyal because we get something. You're loyal to a frequent-flier program essentially because you're going to get the first-class upgrades," he said. "I could care less about anything else they give me." And at 6-1, 240 pounds, he says it goes beyond that. It's also about a comfortable ride.

So when he noticed that travelers in lower categories -- silver, gold and platinum -- were getting those upgrades ahead of him, he was angry. Kaldenberg said he has been told that Delta is giving priority to SkyMiles members who paid the most for their ticket, not based on their level. With Northwest, its highest platinum level trumped everything, he said.

"I want my old Northwest Airlines back."

Delta, however, said it hasn't made any changes to its loyalty program and that the two programs are very similar. But it did not rule out the possibility that a glitch could be to blame.

Either way, complaints are soaring about its SkyMiles program, which has more than 74 million members.

"It's probably the Number 1 complaint of the merger stuff," said Randy Peterson, a national expert on frequent-flier programs and editor of Inside Flyer magazine. He chalked up any problems to technical glitches because of the combined program and the adjustment now that Minneapolis is just a hub.

Bidding wars for travelers

"Minneapolis used to be the big fish in the smaller pond. Now, they're being used differently because they're part of the entire Delta network," he said.

Problems can lead to a bidding war for top travelers, particularly at a time when cash-strapped airlines are cutting back on flights to try to save money.

"They've earned it but it's just not available. There are fewer flights, fewer planes and fewer seats," said Minneapolis travel expert Terry Trippler.

And those frequent fliers get rankled when they don't get the upgrades. "It's not so much for getting a free trip. It's the stature," he said. "It's getting the upgrade. If they can't get it, that's a problem."

Peterson said customers who are unhappy with the program are easy targets for other airlines.

Kaldenberg might already be there. American Airlines is "willing to trade my Delta status for their top-end status if I start flying American," he said. He's considering it, despite having to connect through Chicago O'Hare.

Beginning last fall, he started to notice lower-tiered travelers getting the upgrades he wasn't. It has happened five or six times so far in 2010, he said.

A diamond in the rough spot

But the most recent coach ride, flying from Minneapolis to Orange County, Calif., angered him the most. When he asked a gate agent about an upgrade, he was told he would be flying in coach.

But he glanced down and saw the upgraded boarding passes for five other passengers: two silver and three gold. "I asked, how are they going ahead of me? I'm a diamond."

Airline spokesman Paul Skrbec said it was Northwest's policy and it is Delta's to automatically give first-class seats to full-fare passengers.

After the full-fare passengers are placed, he said, diamonds are ranked according to how much they paid for their ticket, followed by platinum, gold then silver. If the medallion level and fare class are equal, the time of ticketing is the tiebreaker, according to Delta's policy.

Skrbec said he cannot exclude a glitch in the system and has passed Kaldenberg's case along to Delta's SkyMiles team for a closer look.

Peterson said the problem sounds like it could be a technical glitch, stemming from combining both airlines' programs.

But any problems with the program are a big deal, he said. "No one has a higher elite status than the Delta diamond," he said. "It's supposed to be the best, and right now it's not really the best."

Suzanne Ziegler • 612-673-1707