A supersonic Concorde jet made an emergency landing in Cardiff after an engine backfired over the Atlantic. There was a bang, like we hit a brick wall, a passenger said. The British Airways jet, traveling at 1,300 mph, immediately slowed to subsonic speed. Glass and plates were flying, and people were screaming, said passenger Danny Ferris. It was very scary. The 99 passengers paid $6,600 each to fly from New York to London; they rode the last 110 miles on a bus. All will be compensated with frequent-flier miles, but they cant redeem them for seats on a Concorde. The money-losing luxury jets are being retired this month, and all remaining flights are sold out.