June 2007 was the worst month this decade for taxi-out times — the time between leaving the gate and actually taking off — with 462 flights stuck on the ground for more than three hours, the Transportation Department reported. July was not as bad, with 276 flights stuck for more than three hours, though it was still one of the worst months since 2000.

The most famous incident occurred on Valentine's Day, when JetBlue melted down during an ice storm at Kennedy Airport. JetBlue began canceling flights-1,100 over several days. Thousands of passengers were kept on parked planes for up to 11 hours. Others were stuck at airports for days. Similar incidents have been occurring routinely in a system stretched beyond the breaking point.

When aircraft are stranded, conditions quickly deteriorate. Air quality becomes poor. Food runs out. (On many of these flights, passengers have informally organized to share what snacks they had, typically ensuring that children, the elderly, the ill, and others with special needs receive priority.) And worse.

In the first seven months of the year, 27 percent of flights were delayed or canceled, the worst performance since the federal government began keeping statistics in 1995.

U.S. Department of Transportation figures show in the first half of this year, 37,688 air travelers were bumped. In the first half of 2006, 33,275 passengers were bumped.