GoKawiilBy Charlie Precourt, EAA 150237
“Atlantis, Houston,” came the call from NASA’s CAPCOM. “You’re on energy approaching the HAC. Winds for Runway 33 are 090 at 8 gusting 15. You’re go for nominal aimpoint and nominal drag chute deploy. We’re predicting touchdown 2,600 feet (from the threshold) at 195 knots.”
I responded, “Houston, Atlantis copies, on energy.” We were slowing Atlantis through Mach 1, only 3 minutes and 25 seconds from touchdown in our dead-stick descent through 50,000 feet. There was no go-around option.
The CAPCOM, of course, was our astronaut colleague on the console in the control center advising us about our trajectory to the runway. The HAC was our heading alignment cone, an imaginary spiral in the sky we would fly like a curved glide path from 40,000 feet to the ground. The aimpoint and drag chute calls reassured us that conditions were nominal, meaning no abnormal landing procedures required. But our crosswind was pretty stiff, so we’d have to adjust for that. The touchdown airspeed and distance prediction were also what we expected. Armed with all that information, I disconnected the autopilot at 0.95 Mach and about 45,000 feet, and our mission pilot, Eileen Collins, began calling advisory information to me the rest of the way down. This was my first landing at the controls of Atlantis, and it was the culmination of a 10-day mission to the Russian Mir to deliver supplies and a fresh crew for the space station.
In just about the same time it takes us to fly a 5-mile final to touchdown in most of our homebuilt aircraft, I’d be descending from Mach 1 and 50,000 feet to a touchdown at 195 knots! It was pretty amazing to reflect on all that brought us to this point. This is when hundreds of hours of training started to kick in. All of the calls Eileen would give me in the next three minutes were highly scripted and rehearsed so we remained fully coordinated in guiding Atlantis to wheel stop at the Kennedy Space Center.
Although we had spent a lot of time in simulators, the key training that prepared us to land the shuttle was in a modified Gulfstream G-II business jet that flew with the same performance and feel of the shuttle. As I grabbed the controls away from the autopilot, indeed it felt like I was back in the Gulfstream. The miracle of the Gulfstream was its ability to fly the 20-degree dive glide path and maintain 300 knots down final, just as we would in the shuttle. It achieved this by approaching with the landing gear down and modulating thrust reversers while in flight. Where the shuttle used a split rudder to provide a speed brake, the Gulfstream used thrust reversers to give the same result and feel. The left seat was modified to replicate the shuttle commander’s displays and controls, and the right seat was standard Gulfstream, where the safety pilot/instructor would fly to take us into and out of shuttle simulation mode. It was literally a flying simulator. We had to have a minimum of 500 practice approaches in the Gulfstream before our first flight in the shuttle right seat and 1,000 approaches before commanding a mission and performing the landing from the left seat. By this time, I was near 1,700 approaches, and Eileen and I had worked together on this for nearly a year as a crew. We were pretty ready for this!
The shuttle flies an amazing re-entry. Just 30 minutes before re-entry we were out over the Pacific, 400,000 feet up and 4,300 miles from Kennedy, at Mach 25. Overhead Seattle, we were only 17 minutes from touchdown at 200,000 feet in a 70-degree right-wing-down bank, plowing through the atmosphere and getting a view that would cover the entire United States in the next 10 minutes. Coming up on Mach 5 at 120,000 feet, just west of the Florida panhandle, it felt like our trajectory was pointed out past the Bahamas, but as we continued to slow and dig into the thicker atmosphere the nose dropped gently until the Kennedy Space Center was clearly in the middle of our windscreen!
In my head-up display, I had steering cues in pitch and bank, much like an instrument landing system needle’s display, but in the shuttle we used a guidance system that enabled a curved glide path that would guide me around the HAC in a continuous bank. I also had airspeed, altitude, and speed brake readouts. Our goal was to stay right on the glide path, as even one dot low for a short period while up on the HAC could put us so low on energy we might not reach the runway. We would lose 12,000 feet each 90 degrees of turn, and our descent rate would reach over 12,000 feet per minute — there was no room for error!
“Atlantis, Houston, you’re on energy at the 180,” CAPCOM reported.
“Roger, on at the 180,” I replied.
... continue reading