The Engles suffered through several delays, an unscheduled stop and airline staff who, he said, were curt and unhelpful. 'And I don't have enough time to tell you about the extra charges for baggage and food and water, which ran out before half the plane was served,' he said. Despite the experience of the Engles and other passengers, the latest report from the U.S. Department of Transportation shows complaints against airlines dropped nearly 12 percent in September, compared with the same period last year and 32 percent from August 2009. Even factoring in the overall drop in passenger traffic, the complaint rate against the airlines is down from .99 complaints per 100,000 passenger flights to .88 complaints per 100,000 passenger flights. Engle and other airline critics believe the reason for the drop does not reflect improved airline services but a growing frustration by passengers so fed up that they don't file complaints. After all, Engle didn't file a complaint with American or the Department of Transportation. 'They're miserable, and they are resigned that nothing is going to change,' said Kate Hanni, founder of www.flyersrights.com, a Web site that has been pushing Congress to adopt a passenger's bill of rights. Hanni, who has become a vocal airline critic since she and her family idled for nine hours on a tarmac in Austin, Texas, in 2006, said her organization's complaint hotline continues to receive a steady stream of calls from frustrated passengers. Complaints reported to the Department of Transportation come directly from passengers who either call the complaint line, write the agency or file a complaint online. Airlines are required to report mishandled baggage, delayed flights, incidents involving pets, tarmac delays and other specific problems. However, the airlines are not required to report general grievances about service, such as dirty seats, rude staff and excessive fees. Hanni and other critics say it may appear that the airlines are doing a better job because of the deep drop in passenger traffic. The Department of Transportation also reported improved on-time performances for the nation's largest airlines in September, when the on-time rate was 86.2 percent, compared with 84.9 percent in September 2008 and 79.7 percent in August 2009. Airline experts say carriers have an easier time keeping flights on schedule because many have eliminated flights and grounded planes because of dropping demand. More cooperative weather patterns this year also have kept airlines on schedule. Tim Smith, a spokesman for American, conceded that improved weather and declining passenger traffic have helped airlines reduce flight delays, lost luggage reports and other problems. But he attributes the drop in complaints at American to improved service. He said internal data at American shows that the number of complaints by passengers has dropped by 20 percent to 30 percent over last year. He pointed to a new airline effort to deploy customer service workers throughout the terminals to help passengers solve glitches with luggage and flight schedules. As for the Engles' nightmare trip to Detroit, Smith said the airline received more complaints than compliments because people with a gripe are more vocal. Still, he said American Airlines continues to strive to resolve every complaint. 'We are not satisfied if the customers are not satisfied,' he said. The key component of the passenger bill of rights supported by Hanni and other airline critics is a guideline for returning passengers to the terminal when a plane is delayed on the tarmac for more than three hours. Tarmac delays are a major headache, but travelers seem increasingly angry about the fees that airlines charge to check luggage, order a snack, a pillow or a drink. Airline Information, a Miami-based company that organizes conferences and consults for the industry, has created an eight-point bill of rights for passengers who are the target of such fees. Among the mandates: -- All fees must be transparent. -- Customers have a right to know the cost of a flight, plus fees, before paying the fare. -- Customers have a right to a refund if they don't receive the purchased services that were promised. Roger Williams, managing partner at Airline Information, said his company proposed the bill of rights because it was clear that such fees are a permanent part of the industry. Unless airlines manage the fees in a responsible manner, he said he fears the federal government may impose regulations. 'We are trying to stay ahead of the curve,' he said. 