Gene Kranz - Failure Is Not an Option

The remote site drills on rapidly loading the computer programs had brought the site maintenance and operations teams to their peak. You could feel the gritty determination of the operators. The voice exchanges with the remote sites crackled as I handed over the shift to Hodge and his Blue Team for the start of the Gemini 6 countdown early in the morning of December 12, 1965. Hodge, puffing at his pipe, bid me good night as I beat a hasty retreat to the MCC sleeping quarters. Public Affairs had wisely canceled my post-shift press conference. The press would get its story from Kraft’s shift in the morning.

The countdown proceeded without a glitch. The Trench computed the precise liftoff time for the rendezvous and passed it on to Kraft, who passed it to the test conductor on Pad 19. Schirra and Stafford were given the liftoff time, the countdown clocks were synchronized, and the liftoff was scheduled for 8:54 A.M. CST, Sunday, December 12. The controllers leaned forward, alternately scanning displays, reporting the final countdown events, and worrying during the final seconds to liftoff.

The chief worrier at this time was the booster engineer, Charlie Harlan. His console was on the left side of the Trench next to the RETRO. He was located so that if the console communications failed, he could yell out the Titan rocket data to those in the Trench, who needed his data. Seated next to Charlie was astronaut C. C. Williams, observing a small plot board displaying the Titan rocket’s fuel and oxidizer tank pressures. Between Harlan and Williams was the red abort toggle switch. The flight director normally executed the abort command, but the booster response to problems was measured in seconds and so booster engineers act on their own during launch. Their decision time was two to four seconds. Booster’s two main nightmares were calling for an abort when it wasn’t really necessary or ejecting the crew too late—the parachutes wouldn’t inflate or the crew would be swallowed in the boiling, explosive, toxic propellants that we called the BFRC, the big fucking red cloud.

Among many of the major differences between the Mercury capsule and the far more sophisticated Gemini spacecraft was a shift from the escape tower system to individual ejection seats modeled on those used in high-performance jet aircraft. To make the Gemini crew fully aware of conditions that would require ejection in the vicinity of the launch pad, we trained a two-man MCC team—an astronaut and one of my controllers. They monitored the booster for low tank pressures, engine parameters, and pad fallback conditions. The astronauts in the capsule had only meters indicating tank pressures and lights indicating thrust level.

Sitting on the launch pad, the Gemini astronauts would eject horizontally. Either crewman could initiate the ejection sequence by pulling a handle between his legs, which would jettison the hatches and fire both of the catapult rockets for both seats. If the Titan rocket engines shut down, or developed insufficient thrust after ignition, the controllers had only seconds to issue the abort command. The decision process allowed no delay and no error if the crew was to eject in time to avoid the fireball in a pad fallback. The ejection seats were the last resort and were irreversible.

Harlan, Williams, and the crew lived by a few simple ground rules. Booster must see two independent confirmations of a problem before deciding on an abort action, then when the abort command was transmitted, it had to be followed by a voice “Abort” before the crew would take action.

The abort command from the MCC illuminated a red abort light in front of both astronauts. If the crew saw the red light and received a voice-call “Abort,” they were to eject from the Gemini. At liftoff, to avoid a pad fallback, the overall response had to be within three seconds. Three seconds seemed a lifetime to the booster engineers. Harlan made the abort calls for the Titan engines, Williams for the fuel tanks. Both fingered their mike buttons nervously as the countdown clock approached zero for Gemini 6.

The crew also waited through the final seconds. The eyes of Schirra and Stafford were no doubt glued to the clock, engine lights, and tank pressure meters. In the launch sequence, at T=0, the firing command issues engine start commands. The engine lights in the cockpit will blink on briefly, then go out as the engine thrust builds. After two seconds, at greater than 77 percent thrust, the hold-down bolts fire, releasing the booster from the pad. The hold-downs are mechanical attachments that restrain the rocket until thrust is sufficient for liftoff. When the rocket moves one and a half inches, the electrical umbilicals release, which starts the clocks in the spacecraft and on the ground. At this point the mission is committed and liftoff has occurred.

At 8:54 A.M. Central Standard Time, the engines roared to life as steam billowed from the flame bucket. Harlan saw a blip indicating thrust buildup, and the first motion command triggered the clocks in the MCC to start counting up. Schirra and Stafford in the spacecraft felt the initial rumble of engine ignition, the thrust lights blinked, and the Gemini clock started, but then it was strangely quiet. Like a lightning bolt the same thought had to have flickered through the minds of the crew, Harlan, and the launch test conductor. Had liftoff occurred? Were we in a pad fallback? Was 300,000 pounds of rocket, spacecraft, and crew crumpling back to Earth?

Within the seconds allowed for this case, three separate minds came to the single correct conclusion. Harlan called over the voice loop to Kraft, “No liftoff… no liftoff!” In the spacecraft Schirra and Stafford were icemen. They held fire, calmly reporting the cockpit indication as the Martin test conductor initiated the kill recovery procedures.

A launch kill is the most critical single event the operations team faces in the seconds before a launch. The few seconds between engine ignition and the hold-down release is the kill period. With the rocket engines running, the launch system computer rapidly scans the final performance checks. If all is well, the hold-down bolts are released, but if there is a fault, the computer commands an engine shutdown. A complex sequence of commands closes the valves, engages relays, and returns control of the space system to the blockhouse.

During a launch kill everything has to go perfectly. The safing functions and events are critical to fractions of a second, commanding engine shutdown and locking out the hold-down release. The crew, controllers, and launch team must be super-cool, at the highest state of readiness, and all decisions must be perfect.

We not only dodged one bullet that day, we dodged two. The Titan kill occurred at 1.2 seconds because an umbilical released prematurely. Reviewing the data, we found that the engine thrust was already starting to decrease before the umbilical dropped. Engine inspection found a dust cover had not been removed during the engine assembly months before. That day we measured up to the challenge, but we were also lucky.

The turnaround was short and efficient, and much of the redundant testing was deleted. Having only five days of mission lifetime remaining for Borman and Lovell provided the needed incentive. It was going to be a horse race to get Gemini 6 turned around and rendezvous accomplished before we had to bring Borman and Lovell home.

The Cape test team pulled off another miracle, recycling for a successful launch with Schirra and Stafford three days after their kill.

The launch was almost an anticlimax considering all we had had to contend with before Gemini 6 actually lifted off the pad. The rendezvous plan launched Gemini 6 into an orbit below the target, and since the craft in the smaller orbit travels faster, it would catch up with Borman and Lovell’s spacecraft. Ground radar tracking was used by the Trench to compute a series of maneuvers to align the orbits of the two spacecraft and set up the catch-up condition. When the Gemini 6 passed in the smaller orbit below Gemini 7, a maneuver was performed to bring Gemini 6 to a position where the crew could initiate the final braking maneuver.