1952, BOAC's Comet flew 9,440 hours and carried 28,000 passengers. In 1954, two of BOAC's Comet 1s were lost over the Mediterranean. Investigations would prove that the aviation industry would learn much about problems associated with fatigue. At this time Comet 2 and 3 were heading for major success, but the deHavilland company paid a high price for being at the leading edge of technology. Delays resulted in Comet 3 being abandoned in favor of Comet 4, but its late arrival enabled the Boeing 707 to corner most of the jet airliner market. This was not the end of the Comet story. A maritime reconnaissance version, Nimrod, replaced the RAF Shackletons. The Nimrod proved to be most successful, and in 1996, the Nimrod MRA4 was introduced for the RAF, ensuring at least another 25 years of service.