NEW YORK, June 26 (Reuters) - Shares of casino operators tumbled to new lows on Thursday as investors assessed the impact of airline schedule cutbacks and new Las Vegas Strip resort capacity.

“Gaming stocks are very much out of favor,” said Robert LaFleur, an analyst at Susquehanna Financial.

The Dow Jones U.S. Gambling Index .DJUSCA> was down 4.3 percent to a new 52-week low, as the Dow Jones Industrial Average .DJI> dropped 1.9 percent.

JP Morgan analyst Joe Greff on Thursday downgraded shares of MGM Mirage to “neutral” from “overweight” and lowered earnings estimates for the company, citing “unprecedented” uncertainty over visits to Las Vegas and spending by customers who do make the trip.

He also lowered earnings estimates for Las Vegas Sands Corp , noting that Sands is moving aggressively to “put heads on beds” at its Venetian and Palazzo resorts on the Las Vegas Strip by lowering room rates, harming the overall market.

Shares of Sands were down 5.6 percent to $50.42 after falling as low as $49.68, a two-year low. MGM’s shares were down 4.9 percent to $36.98 after touching $35.82, the lowest since September 2006. Boyd Gaming Corp was down 3.6 percent and Trump Entertainment Resorts Inc fell more than 8.1 percent, marking a three-year low.

The operators were already facing headwinds from soft consumer spending amid a weak U.S. economy and soaring gasoline prices; but news that airlines, hit by soaring jet fuel costs, would reduce flight capacity has added another layer of complication.

Nevada’s Tourism Alliance convened an “Air Crisis Briefing” on Monday to discuss the issue.

US Airways Group Inc, the second-largest carrier to Las Vegas after Southwest Airlines Co, said earlier this month that it plans to cut flights to the gambling center by nearly half.

Other air carriers to announce scaled-back flight schedules after the peak summer travel season include Continental Airlines Inc, AMR Corp’s American Airlines, UAL Corp’s United Airlines and Delta Air Lines Inc.

About half of visitors to Las Vegas arrive by air, with the rest driving in, mainly from Southern California. But air arrivals account for about 80 percent of hotel stays.

From now through the end of next year, the room inventory in Las Vegas is slated to jump by more than 11,000 with the opening of casino-hotels like Wynn Resorts Ltd’s Encore, MGM’s City Center and Fontainebleau Las Vegas.

“We are concerned that Las Vegas could lose several million or more air seats at a minimum,” Macquarie Research analyst Joel Simkins said in a research note earlier this week.

Greff estimated that the flight cutbacks will at least cause significantly higher airfares and single-digit declines in flight arrivals into Las Vegas.

“We think the impact of lower airlift capacity and high gas prices couldn’t come at a worse time for the Strip, with four larger mega-resorts set to open over the next three years,” he said in a research note.

In total, work is underway to add more than 40,000 luxury hotel rooms to the gambling corridor — about one-third more than today.

LaFleur said other challenges facing casino operators include smoking bans in some states and increased competition between gambling-friendly destinations.

Overall visitation to Las Vegas so far this year has been down marginally from last year. Nevada casinos won just over $1 billion from gamblers in April, the latest figures available, a 5.1 percent decrease from the same month a year earlier, according to Nevada’s Gaming Control Board.

Simkins said that Las Vegas casino operators may have to continue to reduce room rates and offer more incentives to lure both domestic and international leisure customers.

Deutsche Bank analyst Bill Lerner said some Las Vegas airline capacity could return in the form of charter flights and other packages, but this would likely require the involvement of casino operators.

Courtesy of Guardian.co.uk