One of the most disappointing seats on a Boeing 737 is central to a lawsuit filed in a federal court in San Francisco this week. A San Francisco man joined the class action suit against United Airlines Tuesday, alleging the airline charged him extra for a window seat that was actually next to a wall.

Delta Air Lines and United Airlines were sued on Tuesday by passengers who claimed they paid extra money to sit in "window" seats, only to find themselves placed in seats next to a blank wall. Proposed class actions were filed against United in San Francisco federal court and against Delta in Brooklyn,

Two suits filed this week accuse the airlines of unfairly charging passengers extra fees for window seats that the carriers knew were adjacent to aircraft walls.