So why is it that flying is getting worse, even though airlines are spending billions of dollars to improve service, investing in new equipment such as mobile check-in stations and portable phone banks so travelers can quickly rebook a flight when it is delayed or canceled? The fact is that air travel has never been such a hassle, and the numbers tell part of the story: over the last five years, delays are up 50 percent, flight cancellations are up 68 percent and flights delayed on the runway by an hour or more jumped 130 percent at major airports. Customer complaints to the Transportation Department doubled in 1999 over 1998.

Here is a guided tour of what’s behind the frenzied skies:

You Can’t Get There From Here. It seems Mother Nature would prefer people travel by bus this year. An unusual run of bad weather, featuring long walls of thunderstorms, has crippled airports lately and led to widespread delays and cancellations. After similar problems last summer, the FAA vowed to work more closely with airlines responding to weather slowdowns–for example, FAA and airline representatives now huddle at a single location in Herndon, Va., to figure out the best way to dole out the available airspace. But even the FAA admits the new initiative has fallen short of expectations, and many passengers complain that the delays seem arbitrary. “I don’t know why I kill myself trying to get to the airport on time,’’ says Morton Myaadgen, an IBM executive whose flight from LaGuardia to Charlotte last Wednesday was delayed more than two hours before boarding, and then he sat on the runway for five hours because of bad weather. “I don’t know who to blame, the airline or Mother Nature.’’ Airline executives argue that travelers often point the finger unfairly at them. “When people are stuck in traffic in a cab, do they get angry at the cab driver?” says Gordon Bethune, chairman of Continental Airlines. “We don’t want to sit there any more than you want to sit there.''

All Aboard. Part of the problem is crammed planes. Thanks to the strong economy, U.S. airlines are expected to carry a record 665 million passengers this year, up 5 percent from last year. On average, planes are about 76 percent full these days, also a record. That’s good news for airlines, which are profitably loading more passengers on each flight, and bad news for passengers, since irritations build exponentially in tight quarters. Clifford Winston of the Brookings Institution has calculated that consumer complaints have risen in tandem with the crowding of planes. When the statistics are adjusted for that growth, consumer complaints have actually held fairly steady. “I don’t think the public would be so angry if there weren’t so many people on the plane with them,’’ says Winston.

Blame the Airlines. After all, they’re a big part of the problem. The inspector general’s report noted, for example, that some airlines repeatedly blamed flight delays and cancellations entirely on the FAA’s traffic control system even when the real cause was weather, flight-crew shortages or a mechanical problem with the plane. Another beef: flight monitors and gate displays will say a flight is on time, even though there’s no aircraft at the gate at the time of the flight.

As a result, airlines have a credibility problem with many passengers. “I think they say it’s weather even if it’s not,’’ said Jessica Caldwell, who was told her flight out of LaGuardia was canceled last Wednesday because of weather. Caldwell has her suspicions. “If it’s weather related, then they don’t have to do anything about it–no hotel vouchers, no coupons.’’ Even when the airlines try to make the system better, they tend to focus on the wrong things, some experts say. Despite the airlines’ initiative to improve service, the inspector general said the industry “does not directly address underlying reasons for customer dissatisfaction, such as extensive flight delays, baggage not showing up on arrival, long check-in lines and high fares in certain markets.’’ And many airline employees at airports seem more focused on enforcing the latest policy on matters such as carry-on baggage than providing friendly service, according to Mike Boyd, an airline industry consultant. “It’s worse than Marine boot camp,’’ Boyd adds. “Airlines are arrogantly processing passengers, rather than treating them like customers, and they’ve done nothing to simplify the procedures.’’ The industry says its commitment to making travel easier is real. “We are focused, hundreds of thousands of us, on improving service,’’ says David Fuscus, a spokesman for the Air Transport Association.

The inspector general said the airlines still have a long way to go before they restore customer confidence (and get politicians off their backs in Washington, where airline bashing is a popular contact sport). Among other things, the airlines need better compliance systems to check whether they’re even meeting the goals they set for themselves last year, including better notification of delays, faster responses to customer complaints and catering better to passengers’ needs during long delays on the runway. “We found that most of the airlines did not have such a system in place,’’ the report said. Hungry for more detail? You can print up the inspector general’s report from the Internet (oig.dot.gov) and read it next time you’re stuck on a tarmac for four hours. When you’re done with it, you can then fold up the pages into paper airplanes and sail them through the cabin. At least you’d feel some sense of control over those flights.