10:33:18 NASA-1: “OK.”
10:33:24 NASA-1: “A little bit high, Mike, but real good shape.”
10:33:25 [Mike makes two more right yaw control inputs that increase the heading drift rate to the right.]
10:33:28 [Mike makes right, left, and then right yaw control inputs which further increase the right heading drift. His heading is now misaligned 50 degrees to the right of the flight path.]
10:33:33 NASA-1: “And we got you coming down hill now. Are your dampers still on?”
10:33:37 Chase-1: “Dampers still on, Mike?”
10:33:39 Adams: “Yeah, and it seems squirrelly.”
[At this time, the heading has deviated 90 degrees from the ground track. The aircraft is turned sideways to the flight path. Mike is apparently unaware of this gross heading misalignment.]
– – [Squelch break.]
10:33:44 NASA-1: “OK, have you coming back through 230 [230,000 feet altitude]. Ball nose, Mike.” [The heading deviation is increasing in rate and the aircraft apparently begins to spin.]
10:33:49 [At this time, the aircraft has turned 180 degrees from its ground track. The tail of the aircraft is pointed along the ground track.]
10:33:50 NASA-1: “Let’s watch your alpha, Mike.”
10:33:58 NASA-1: “Let’s not keep it as high as normal with this damper problem. Have you at 210. Alpha, beta, and check your alpha, Mike.”
10:34:02 Adams: “I’m in a spin, Pete.”
[At this time, the aircraft has turned completely around and is again heading along the flight path momentarily as it continues to spin.]
10:34:05 NASA-1: “Let’s get your experiment in and the camera on.”
10:34:13 NASA-1: “Let’s watch your theta, Mike.”
10:34:16 Adams: “I’m in a spin.”
10:34:18 NASA-1: “Say again.”
10:34:19 Adams: “I’m in a spin.”
10:34:21 NASA-1: “Say again.”
I was in the control room monitoring the flight when this conversation was taking place. I heard Mike say, “I’m in a spin,” three times very clearly. I know that Pete heard Mike also, since almost all the witnesses in the control room mentioned those calls in their statements after the accident. The only conclusion that I can draw is that Pete subconsciously did not want to hear that call. I, too, did not want to hear that call or believe it. My mind said, “What the hell do you mean, you’re in a spin. How can you spin traveling 3,500 MPH? There is no such thing as a hypersonic spin. Spin? What do you mean spin. You’ve got to be kidding, Mike.”
Pete may also have mentally refused to acknowledge Mike’s call because he knew there was nothing he could do to help Mike. There was no known spin recovery technique for a hypersonic spin, since no one had ever anticipated such a phenomenon. No one had done any wind tunnel tests or analysis to confirm or deny the existence of such a phenomenon. Pete and the other control room occupants were completely helpless.
While I was trying to convince myself that this must be a bad dream, I noticed Whitey quickly grab Mike’s wife and mother and lead them out of the control room viewing area. Whitey knew we had a serious emergency in progress and he wanted to somehow spare Mike’s wife and mother the brutal details, at least for a few moments.
There was a time when wives were discouraged from observing test flights. Under those conditions, the wife would learn of an accident or death sometime after the fact under more controlled conditions. The Challenger accident was an example of a very traumatic event that was observed in real time by the wives, husbands, and other family members. I am not sure that is the best way to receive the bad news.
Before the days of instant communications, soldiers would go off to war and not be heard of, or from, for months and even years in the case of the crusades. If a soldier was killed, his wife and family only heard of it after the fact—much too late to do anything about it. Conversely, in the Vietnam war, wives were watching nightly TV newscasts in an attempt to recognize their husbands during battle or among the dead or wounded. If you observe such a thing in real time, you are almost forced to try and influence the outcome and when you realize you cannot, you are even more devastated. Again, I am not sure that is the best way to receive the bad news.
10:34:27 NASA-1: “OK, Mike, you’re coming through about 135 [135,000 feet altitude] now.”
10:34:34 NASA-1: “Let’s get it straightened out.”
[Pete apparently finally admitted to himself that the aircraft was in a spin.]
10:34:36 [At this time, the spin apparently breaks. The angle of attack decreases to a nominal value and the yaw rate decreases to zero. Simultaneously, the aircraft horizontal stabilizers begin to oscillate ±10 degrees in a sawtooth manner. These stabilizer motions begin to force the aircraft to oscillate in pitch and roll. The aircraft motions are initially small, but begin to rapidly increase in amplitude as the aircraft continues its descent into the atmosphere. The aircraft is plunging into the atmosphere at over 3,000 feet per second. This is the same control system oscillation that I had previously encountered on one of my flights. On my flight these oscillations had become extremely violent, slamming me against my restraint harness with great force before they finally stopped.]
10:34:37 – – [Two squelch breaks.]
10:34:42 NASA-1: “OK, you got theta zero now. Get some angle of attack up.”
10:34:50 NASA-1: “Coming up to 80,000, Mike.”
10:34:53 NASA-1: “Let’s get some alpha on it.”
10:34:54 [At this time, the aircraft fuselage buckled due to excessive side loads produced by the large, violent aircraft motions. These motions were a result of the continuing horizontal tail surface oscillations which were producing higher and higher oscillatory g loads as the aircraft continued to descend. Radar altitude at this time was approximately 80,000 feet.]
10:34:57 NASA-1: “Get some g on it, Mike.”
10:34:59 NASA-1: “Let’s get some g on it.”
[At this time, telemetry data ceased. Just prior to loss of telemetry data, the oscillatory g forces exceeded ±13 g Radar altitude was 62,000 feet. Velocity had decreased to less than 4,000 feet per second, or about Mach 4. The aircraft was descending at approximately 2,500 feet per second and broke into many pieces at this time.]
10:35:02 NASA-1: “We’ve got it now. Let’s keep it there. Coming around.”
10:35:09 NASA-1: “OK, let’s keep it up, Mike.”
10:35:14 NASA-1: “Keep pulling up. Do you read, Mike?”
10:35:20 NASA-1: “Let’s keep pulling it up, Mike.”
10:35:27 NASA-1: “OK, 130 let’s head down that way.”
[Pete is telling the C-130 to head down toward Cuddeback Lake.]
10:35:37 NASA-1: “He was abeam Cuddeback 130, three-five-eight.”
10:35:42 NASA-1: “Chase-4, do you have anything on him?”
10:35:44 Chase-4: “Chase-4, negative.”
10:35:47 NASA-1: “OK, Mike, do you read?”
10:35:52 Chase-4: “Pete, I got dust on the lake down there.”
10:35:55 NASA-1: “What lake?”
At this time, the long wait began. The forward fuselage portion of the aircraft was finally spotted by the backup Chase-4 at approximately 10:52. The landing recovery helicopter had proceeded northbound from Edwards as soon as the pilot heard Mike’s call that he was in a spin. It arrived at the crash site at 10:57. Colonel Cotton, the B-52 pilot, said, “At 11:02 the unwanted announcement was heard from the helicopter that the remains of the pilot were in the cockpit.”
Colonel Cotton had become an unwilling witness to a second major catastrophe. Joe Cotton had been flying chase on the B-70 when Joe Walker’s plane collided with the B-70. Joe Cotton called out the fateful words on that occasion, “Midair. Midair.”
Based on the accident investigation, somewhere during the climb, Mike had apparently started experiencing the symptoms of vertigo. On a previous altitude flight, Mike had experienced severe vertigo from the time he had shut the engine down until
he had reentered the atmosphere. Mike’s words in the debriefing on that flight were, “I didn’t know what the hell I was doing.”
On a subsequent altitude flight, Mike again suffered extreme vertigo. He related that information off the record to a couple of flight planning engineers during a discussion at lunch the day after the flight.
Mike apparently did not mention this to the flight surgeon, possibly for two reasons. First, all of the X-15 pilots suffered from vertigo during the climbout. It was common knowledge that the high g forces in the X-15 during climbout caused vertigo. Every pilot thought he was climbing straight up or was even over on his back at engine shutdown. So Mike had no reason to suspect that he was experiencing something unique. He was, however, apparently disoriented for a much longer period of time than the other pilots, based on his previous postflight comments and his unofficial conversation with the flight planning engineers. He may or may not have been aware of this.
The second possible reason that Mike may not have mentioned this to his flight surgeon is that he may have been concerned about being grounded or at least taken off the X-15 program. This was obviously a possibility. Aerospace flight surgeons were generally quite conservative in that era. If a pilot on a major aerospace program showed any abnormal symptoms of any kind, he was usually grounded or removed from the program. Two classic cases were Deke Slayton and Alan Shepard. Both were grounded for years for minor abnormalities. A severe vertigo problem would undoubtedly have been considered disqualifying and Mike may not have wanted to surface the problem.
I could personally empathize with Mike. I had participated in a research program on the human centrifuge at Johnsville, Pennsylvania, in 1959. I spent one month being whirled around in the centrifuge for several hours a day at both low and high g’s. At the end of that program, I had serious disorientation problems. If I moved my head back rapidly, I would become completely disoriented and think that I was back in the centrifuge at Johnsville whirling around on a test run. The disorientation would last as long as a full minute. That problem plagued me for over 6 months before it finally cleared up. I voluntarily admitted that I had a problem. It was duly recorded in my physical record, but I was not officially grounded.
Mike was, unfortunately, the victim of ignorance. No one understood the effects of g forces on the human sensory system. They still do not. Astronauts are still suffering from space sickness. He obviously knew he had a problem. He also did not want to be grounded. He may have been subconsciously appealing for help when he discussed his problem with the flight planning engineers. Unfortunately, they had no appreciation for the problem.
Although we strongly suspected that Mike had misinterpreted his instruments due to vertigo and responded to the roll guidance error indication with yaw control inputs, to misalign the airplane with the flight path, we could not verify this without knowing what the cockpit instruments were indicating during ballistic flight. We needed the cockpit camera film to verify this. The problem was that the cockpit camera was mounted on the inside of the canopy and the canopy was missing from the forward fuselage wreckage. Apparently, the canopy had come off in flight, but where? The airplane had failed structurally while descending through 65,000 feet altitude. Whether the airplane disintegrated at that point or whether it shed parts all the way to impact, no one knew. We organized a search party to locate aircraft parts. Over half of the aircraft was missing.
The location of the structural breakup point was pinpointed on a large scale topographic map using data from our radar tracking maps. The breakup point, the aircraft track over the ground, and the forward fuselage impact point were plotted on the topographical maps. This information provided some general guidance for the search party. The terrain in the proposed search area was, however, extremely rugged—steep rock strewn hills with numerous narrow dead-ended canyons—an ideal place for prospecting, but a hell hole for a search party. The search area was just to the southwest of Death Valley, an ominous reminder of the business at hand.
The search party quickly began finding parts and identifying the location of each part on the topographic maps. We soon surmised from a master plot of the location of the various parts, that the aircraft had indeed disintegrated at the point of the initial structural failure. The parts then impacted in a pattern dictated by their individual density. Those with higher densities traveled farther along the flight path before impact. Using this information, we began to identify more fruitful search areas for the canopy. After an agonizing and frustrating search, the canopy was finally located. It was in excellent condition with no significant damage. It had apparently sailed down to a smooth landing.
The searchers were ecstatic. They had located the missing evidence. But, on examination of the canopy, they found that the cockpit camera had torn loose and was missing. What a blow. They had not found the missing evidence and worse, the part they now had to find was quite small—about the size of a Cracker Jack box. We were now literally looking for the needle in a hay stack. A small camera with a neutral color could blend in with the rocks and brown vegetation like a chameleon.
An early winter rain made the search area inaccessible for about a week. Another search party was organized after the area dried out. The search party lined up in a long line abreast and began walking up and down the hills and gullies in a precise pattern. This technique paid off handsomely. The camera was located on the second pass along the 2-mile route. Again, the searchers were quickly disappointed. The film magazine was missing from the camera. We were now forced to search for something even smaller—something the size of a pack of cigarettes. The search continued but with no further success.
By this time we gave up hope of ever finding the film magazine, but a few die hards would not give up. Another search party was organized and again, the searchers lined up in a long line abreast, 10 feet apart, and marched up and down the rugged terrain for a last, final search effort. Again, it paid off. The film magazine was found intact. It was hand carried to a photo lab back on the East Coast that specialized in salvaging damaged film. The film had been slightly damaged by the rain, but it was completely readable. That cockpit camera film provided vital information in the accident investigation.
The accident report states in the summary that:
The only unusual problem during the ascent portion of the flight was an electrical disturbance that started at an altitude of 90,000 feet and that effected the telemetered signal, the altitude and velocity computer associated with the inertial platform and the reaction controls that operate automatically in conjunction with the MH-96 adaptive control system. Although the pilot always had adequate displays and backup controls, the condition created a distraction and degraded the normal controls. As the aircraft approached the peak altitude of 266,000 feet, it began a slow turn to the right at a rate of about 0.5 degrees per second. This rate was checked by the MH-96 system which operated normally for a brief period so that at peak altitude, the aircraft was 15 degrees off heading. Then the pilot, apparently mistaking a roll indicator for a sideslip (heading) indicator drove the airplane further off in heading by using the manual reaction controls. Thus the aircraft was turned 90 degrees to the flight path as the aerodynamic forces became significant with decreasing altitude. The aircraft continued to veer and entered what appeared to be a classical spin at an altitude of about 230,000 feet and a Mach number of about 5.0.
Some combination of pilot action, the stability augmentation system, and the inherent aircraft stability caused the aircraft to recover from the spin at an altitude of about 120,000 feet and a Mach number of about 4.7. As the aircraft recovered from the spin, however, a control system oscillation developed and quickly became self-sustaining. At this time the airplane was descending at a rate of about 160,000 feet per minute and dynamic pressure was increasing at nearly 100 pounds per square foot each second. There was a corresponding rapid increase in the g forces associated with the oscillation, and structural limits were exceeded. The airplane broke into many pieces
while still at high altitude probably in excess of 60,000 feet, and fell to the earth northeast of Johannesburg, California.
The pilot, probably incapacitated by the high g forces did not escape from the cockpit and was killed on ground impact. The accident board concluded that the accident was precipitated when the pilot allowed the aircraft to deviate in heading and subsequently drove it to such an extreme deviation that there was a complete loss of control. The board believes that these pilot actions were the result of some combination of display misinterpretation, distraction, and possible vertigo. The board further concludes that the destruction of the aircraft was the result of a sustained control system oscillation driven by the MH-96 adaptive control system that caused the divergent aircraft oscillations and aerodynamic loads in excess of the structural limits. The electrical disturbance was attributed to the use in one of the scientific experiments of a motor that was unsuited to very high altitude environments.
In my opinion, there was no pilot error involved. I also believe the accident board shared this opinion. I think everyone believed that Mike suffered severe vertigo during this flight. There were many malfunctions and distractions that were contributing causes which severely compromised the control task, but Mike was an excellent pilot and under normal conditions he would have successfully coped with these problems. As we have learned from painful experience, vertigo can be extremely incapacitating. It can effect the best or the worst pilot and can strike at any time. Amazingly, the pilots of that era were not routinely subjected to any specific test for vertigo susceptibility. Vertigo tests were apparently considered passé.
My personal conclusion was that Mike was thrown off the bull, and the bull killed him.
Chapter 10
The End
After Mike’s death, there was a reassessment of the program. The program had been winding down. Most of the basic research work had been accomplished and we had flown most of the proposed follow-on experiments. Support for the program was dwindling in NASA, the USAF, and in Congress. The scramjet development was several years behind schedule, and the X-15 delta wing proposal was in limbo due to lack of high-level support. There was also some trepidation about the possibility of another accident. Bikle could have taken the easy way out and shut the program down. Instead, he elected to fly for another year in the hope that the scramjet or delta wing experiments might come to fruition. Bikle was very concerned about losing a national capability to operate advanced research aircraft. By extending the program at least another year, Bikle would also be able to end the program in a more positive fashion if the program finally had to be cancelled.
At the Edge of Space Page 34
