East Coast travelers on Monday experienced a new round of cancellations and delays as another winter storm grounded planes. But many of those flights won't be counted as late or canceled in the government's on-time statistics.

A recent federal report found that passengers are getting only part of the picture, and that the industry's on-time performance is actually much lower than billed. And a proposed rule that would require carriers to provide a more accurate picture has itself been delayed — and has yet to be adopted more than two years after it was proposed.

On-time statistics capture only 76 percent of domestic flights at American commercial airports, according to a report released in December by the Transportation Department's inspector general.

These statistics do not include many segments of the industry that have grown in recent years: international flights, flights flown by Spirit Airlines, or many flights operated by regional carriers and other partners.

The proposed rule would increase the number of ­carriers required to report data about delays and cancellations, improving the accuracy of the on-time statistics that the government announces every month.

It is part of a set of passenger protections that began the lengthy federal rule-making process in April 2011, but the announcement of the final proposed rule has been postponed multiple times.

The latest target date for its release, Jan. 24, came and went with no action by the Transportation Department, ­ leaving passenger advocates irate.

"I'm totally frustrated by this," said Charlie Leocha, director of the Consumer Travel Alliance, a passenger advocacy group. "I've written letters, I've stood in front of the DOT with a big banner, I've gone on TV. Now we're up to around 1,000 days since the rule was proposed."

The long-delayed passenger protections have been under review by the Office of Management and Budget since April.

Perhaps a thornier problem for data collectors is how long passengers, not flights, are delayed.

new york times