more flexibility to employ tactical aircraft in a fast-changing battle scenario. It was the first Navy aircraft to incorporate a digital multiplexing avionics bus, enabling easy upgrades. The Hornet was designed to reduce maintenance, and as a result, has required far less downtime than its heavier counterparts, the F-14 Tomcat and the A-6 Intruder. Its mean time between failures is three times greater than any other Navy strike aircraft, and requires half the maintenance time. Its General Electric F404 engines were also innovative in that they were designed with operability, reliability, and maintainability first. The engine, while unexceptional in rated performance, demonstrates exceptional robustness under various conditions and is resistant to stall and flameout. The F404 engine connects to the airframe at only 10 points and can be replaced without special equipment: a four-person team can remove the engine within 20 minutes. The aircraft has a top speed of Mach 1.8 at 40,000 ft. The engine air inlets of the Hornet, like that of the F-16, are of a simpler "fixed" design, while those of the F-4, F-14, and F-15 have variable geometry or variable intake ramp air inlets. A 1989 USMC study found that single-seat fighters were well suited to air-to-air combat missions, while dual-seat fighters were favored for complex strike missions against heavy air and ground defenses in adverse weather—the question being not so much as to whether a second pair of eyes would be useful, but as to having the second crewman sit in the same fighter or in a second fighter. Single-seat fighters that lacked wingmen were shown to be especially vulnerable. Operational history United States Entry into service McDonnell Douglas rolled out the first F/A-18A on 13 September 1978, in blue-on-white colors marked with "Navy" on the left and "Marines" on the right. Its first flight was on 18 November. In a break with tradition, the Navy pioneered the "principal site concept" with the F/A-18, where almost all testing was done at Naval Air Station Patuxent River, instead of near the site of manufacture, and using Navy and Marine Corps test pilots instead of civilians early in development. In March 1979, Lt. Cdr. John Padgett became the first Navy pilot to fly the F/A-18. Following trials and operational testing by VX-4 and VX-5, Hornets began to fill the Fleet Replacement Squadrons VFA-125, VFA-106, and VMFAT-101, where pilots are introduced to the F/A-18. The Hornet entered