There appears to be an airline seat worse than the middle one between an overweight passenger and a colicky infant, at least according to one exasperated passenger whose letter of complaint is bouncing around cyberspace these days.

It's seat 29E, next to the lavatory on a flight that one Continental Airlines passenger said set him back $400. He fired off an angry letter to the airline describing his misery, copies of which have been posted on Flyertalk.com and other travel Web sites.

"Is it the stench of the sanitation fluid that is blown all over my body every 60 seconds when the door opens? Is it the woosh of the constant flushing? Or is it the [passengers' posteriors] that seem to fit into my personal space like a pornographic jigsaw puzzle," he wrote while on the Dec. 21 flight between San Diego and Houston.

The passenger said he created what he called a "stink shield" by hanging a blanket from the overhead bin between him and the lavatory.

A Continental spokesman said the airline contacted the passenger to apologize for his unpleasant trip. The flight was full, the airline said, otherwise they would have moved him to another seat.

"If there were a quick and easy solution to his concern, we would do it in a whiz," said the spokesman, who couldn't resist a pun of his own. "Notwithstanding the embellished humor in the letter, we don't pooh-pooh any of our customers' concerns, and have apologized."

The letter was stamped "received" on April 13 by Continental's customer care department. The name of the passenger was removed. How it made its way to cyberspace is unclear. Continental declined to release the passenger's name.

The letter, however, did reach Kenneth M. Mead, the Transportation Department's inspector general. At a recent industry luncheon, Mead told Biz Class that his department planned "to look into it," without offering specifics. His office has since passed the matter on to the Federal Aviation Administration as well as Transportation's Office of Aviation Enforcement.

But it seems the Continental passenger may not have been totally accurate in his account. According to a floor plan of the aircraft, seat 29E is not directly next to the lavatory. On the Boeing 737-800, seat 29D is in fact the seat closest to the lav. So unless the passenger wrote down the wrong seat number or traded seats, he was not as bad off as he could have been.

Continental is obviously not the only airline that has seats adjacent to the lavatory. American Airlines' 757-200 has three rows of seats near the lavatories. Row 26 is so situated on Northwest's Airbus A320s. Same for Delta's Boeing 737-800s.

Other aircraft are configured differently to avoid such placements. For example, one of US Airways' most popular planes, the 737-300, has two galleys between the last row of seats and the lavs. United Airline's 737-500 has two galleys and two exits between its last row of seats and lavatory.

Savvy travelers say the best way to check on the location of a given seat is by going to Seatguru.com, a four-year-old Web site that contains more than 200 aircraft configurations from 26 of the world's largest airlines. The Web site is popular with travelers who want insight into finding those seats offering the most legroom, or who want to avoid seats that don't recline.

Ana Luisa Aldana, a San Francisco management consultant, checks out Seatguru before she books a flight to make sure she's avoiding the "outhouse" seat, especially on flights lasting two or more hours.

Aldana's biggest complaint with such seats is the line of passengers who wait for the lavatory to open by standing in the aisle, seemingly unaware that they're brushing up against passengers seated nearby.

"They slouch on your seat and intrude on your space," she said. "If you're on a transatlantic or transcontinental flight, you're just stuck there. Heaven help you."

Some travelers actually prefer the seat in the back of the plane closest to the facilities. Susan Daimler, Seatguru's vice president of marketing, said the seat is often closest to the galley so a passenger can get a quick drink or snack before anyone else. They also can be the first one in the lavatory before a line starts forming on longer flights. And for that passenger on standby, a seat next to the lavatory is better than no seat at all.

"It's pretty amazing. One man's treasure is another man's worst flying experience," Daimler said.

Short of erecting a stink shield, some seated passengers have their own strategies for coping with passengers' posteriors in such close proximity. Jonathan Esslinger of Chantilly said he always makes sure to focus on the book in his lap rather than the passengers moving in and out of the latrine. He also makes sure to have his noise-canceling headphones to eliminate the "woosh" sound of the flush.

Because Richard Beels has sat in the seat next to the lavatory himself, the Scranton, Pa.-based network consultant said he tries to be more courteous when using the lavatory. That means not opening the door until the flush has completed.