When specified major maintenance was performed on an Air Force aircraft, a follow-up flight called a functional check flight (FCF) would be required. A squadron would have two pilots qualified to fly FCFs. I was fortunate to be an FCF pilot for both the OV-10 and the F-16.
An FCF followed a very structured flight profile to check out all of the plane’s systems. The flight profiles were pretty simple to fly but also a lot of fun.
An FCF would be flown with a completely clean aircraft, which means no external fuel tanks, no bomb racks, and no AIM-9 sidewinders on the wingtips. This applied especially to the F-16, which was never flown without external fuel and some type of weapons.
The OV-10 FCF
An OV-10 FCF had two highlight maneuvers. For the first, I would climb to 15,000 ft altitude. In normal operations, we never flew above 10,000 ft and we didn’t wear oxygen masks. I would wear my oxygen mask for an FCF, which was required for flights above 10,000 ft.
From 15,000 ft, I would dive straight down until I reached a speed of 350 knots (about 403 mph). 350 was the max rated airspeed for the OV-10. I always wondered about the purpose behind the high-speed dive. To see if the wings stayed on?
Soon after the death dive, I would shut down the engines. First one, then restart it. Then the second and restart it. A handful of times, one would not restart. Flying the OV-10 single engine was a big pain in the leg, as in having to stand on a rudder peddle for 20 minutes of flying to get back to the base.
I flew OV-10 FCFs at Patrick AFB, Cocoa Beach, FL, and the missions were accomplished about 20 miles out over the Atlantic.
The F-16 FCF
My F-16 FCFs were at Nellis AFB, Las Vegas, NV. Flying a clean jet, the F-16 FCF departure was always a thrill. With a full-afterburner takeoff, lift-off would be at about 150 knots (from memory), and I would hold the jet just above the runway until I hit 400 knots (460 mph), which would be about halfway down the runway. At 400 knots, I would pull the jet into a vertical climb and zoom straight up to 15,000 ft., or almost three miles. The F-16 would still be going 400 knots straight up when I reached 15,000. Then, I would roll the jet level to start the rest of the FCF profile. The most thrilling moment of my Air Force career happened at this point during an FCF, but I am saving that story for a later date.
The supersonic Mach run was another fun step in an F-16 FCF. The requirement was to go at least Mach 1.4 at 40,000 ft. in level flight. The Mach target works out to about 800 knots true airspeed or 924 mph. I don’t remember any FCFs that didn’t hit the Mach 1.4 target. A few barely squeaked by. Most would hit Mach 1.5.
There was a Saturday morning FCF when I had a very fast F-16. I saw Mach 1.82 and 1,082 knots true airspeed in the HUD. I was going the fastest I ever went in the F-16! Then a little voice in my head went, “I wonder how high I can go?” That, too, is a story for another day.
Maintenance Crew
Final FCF factoid. Jets don’t always break down at the home base. Being an FCF pilot was like being on call to go rescue a stranded aircraft. I would travel with a maintenance crew. They would find and fix the issue, and I would fly the FCF flight. The external gear would be remounted if it passed, and I would fly the aircraft back home.
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Good Lordy! The whole "let's turn the plane off" scenario... NOPE! 🫨
Great read.
Great read!!! You write very well. It was so engaging.