We?ve Got Nothing Left

On a cloudless morning in April of this year, a C-5B transport of the 436th Airlift Wing took off from Dover AFB in Delaware, bound for Ramstein Air Base in Germany on a routine supply mission. The C-5 is the United States Air Force's largest transport; this one's takeoff weight was 742,000 pounds, including a quarter-million pounds of fuel. Aboard were 17 people; the crew included three pilots and three flight engineers, collectively representing more than 26,000 hours and 92 years of C-5 flight experience.

Shortly after takeoff the crew observed an intermittent warning light for an unlocked thrust reverser on the number two engine, the inboard engine on the left side of the aircraft. An unlocked reverser is a potential hazard-there is a chance of unexpected deployment in flight-and so after due deliberation and cross-checks the crew secured the engine and turned back to Dover. They did not declare an emergency, but did request an expedited approach. They anticipated a routine landing, though at a higher than usual weight; they had, after all, three good engines and a perfectly functional aircraft. A few minutes later, the C-5 lay, a mangled wreck, a third of a mile short of the Dover runway. Thankfully fire did not break out and all aboard survived, although some were seriously injured. Newspaper reports the next day hailed the fatality-free crash as a miracle.

Two months later the Air Force released the report of its investigation of the accident. It turned out to have been a miracle, all right-a miracle of crew interaction gone awry. So bizarre and striking was the story that the investigation uncovered, that an internal Air Force video simulation, accompanied by cockpit voice recorder dialogue and animated indications of relevant instruments, was soon making its way around the internet. I, for one, received it from three different people.

In order to allow the right seat pilot, a C-5 instructor with five years and 2,330 hours in type, to log the sortie, the left seat pilot, who had flown the takeoff, had turned control of the aircraft over to him. Investigators identified as causal to the accident three procedural errors, all of which involved, in one way or another, the right seat pilot.

After deciding to return to Dover, the crew had informed the controller of their intentions and had elected to cancel IFR and make a visual approach. They chose Runway 32, although the 6-knot surface wind was from the south, because it was the longest runway. Presumably they wanted plenty of room to let the heavily loaded airplane roll out with moderate braking. Runway 32 did not have a precision instrument approach, but it did have a PAPI, or visual glideslope. It was a perfectly clear day, and there was no reason to anticipate any difficulty with a visual approach. The approach began, however, hundreds of feet below the PAPI glideslope and never intercepted it.

The flight received landing clearance six miles from the runway, about 1,200 feet above the ground and about 15 knots above the bug speed of 166. Flaps were at 40 percent-the recommended setting for an engine-out approach. Shortly after, however, the pilot called for "landing flap," and the flaps came down to 100 percent. Full flaps lowered the bug speed to 146 knots and would shorten the landing roll, but also increased the drag that the three remaining engines would have to overcome. Ideally, full flaps, if used at all on an engine-out approach, would be reserved until landing was assured, not when the airplane was still miles away from the runway and, incidentally, at an unusually low altitude. Nevertheless, the C-5 was perfectly capable of landing from this position and with this flap setting, on three engines, and neither the left seat pilot nor the third pilot, who was sitting in the jumpseat behind the other two, commented on the early selection of full flaps.

Just before calling for landing flaps, however, the pilot had made an unconscious slip that went unnoticed not only by him, but by the other five flight crewmembers as well. He briefly brought the throttles for the three good engines back to idle and then, when he brought power back up, he somehow confused the two middle throttles. He inadvertently advanced the number two throttle along with one and four, while leaving number three at idle. Now, the number two engine had been shut down, and so moving its throttle produced no effect. The vertical-tape rpm gauges for the engines-this C-5 had been modernized with a glass cockpit-clearly displayed the two outboard engines operating at or near 100 percent rpm while the two inner engines remained at idle or below; but no one took notice.

Two engines were not powerful enough to make the heavy-laden aircraft fly level with full flap. Already several hundred feet below the visual glideslope at the start of the approach, it continued to descend. It should have been at 900 feet agl three miles from touchdown, 500 at two miles, and 300 at one mile. Instead, it was at 500 feet at three miles, 325 at two, and 150 at one mile.

Meanwhile, two flight engineers, unheard by the pilots, discussed the flap setting. One, who believed the flaps were at the recommended 40 percent, was surprised to learn that they were at 100 percent and suggested to the other that they point out the discrepancy to the pilots. The other flight engineer, however, demurred, saying that it was too late. In any case, the lesser flap setting was only a recommendation, not a requirement.

At 1.7 miles from the runway and 225 ft. agl, the pilot, his expression suddenly edgy, said "Guys, I'm concerned. We've got nothing left." Amid a rising chorus of synthetic voices warning of sink rate and approaching terrain, the pilot now, in a last desperate bid to reduce drag, called for the flaps to be raised to 40 percent. As the flaps came up, the airplane, decelerating below 127 knots as the pilot struggled to convert into altitude what little speed remained, pitched up to an angle of attack of 20 degrees and began to stall. There was no time, nor any altitude, for recovery. The giant transport first struck a wooden utility pole and then, an instant later, the ground, first losing its aft fuselage and empennage, then slamming its nose down with a force of 30 Gs, buckling its left wing and shedding its left outboard engine. It slid nearly 2,000 feet before coming to rest in three pieces.

Since landing with three engines is a routine procedure in the C-5, the faulty thrust reverser lock indication and the decision to secure the number two engine were not considered causal to the accident. Instead, the investigation board selected, from a standard list, a number of human factors, including fatigue, inattention, complacency, faulty risk assessment and failure to completely brief the intended procedure. They noted that the landing could have been safely completed if the pilots or flight engineers had recognized the discrepancy between the throttle positions and the rpm indications, or if the flaps had been left at 40 percent in the first place, or if the approach had been initiated from the proper altitude. Correcting any one of these factors would have been enough to prevent the crash.

As to what caused the right seat pilot to confuse the number two and number three engines, it is possible that the fact that he was flying from the right seat had something to do with it; usually when one is practicing engine-out procedures in a simulator, one is in the left seat. Left-right confusion is not uncommon in various kinds of tasks. What is more unexpected is that no one else in the cockpit took note of the inappropriate engine power indications, and that the pilot himself, who was very familiar with the performance characteristics of the C-5, was seemingly not more concerned, earlier in the approach, that the airplane was not as responsive to power as it should have been. Not only would it have been unexpected that the airplane could not climb with full power on three engines, but the fact that it required no corrective rudder for thrust asymmetry might also have seemed strange. Yet at no point, until he said "Guys, I'm concerned," did the pilot verbalize any misgivings-if he had them-about the airplane's performance. Even then, his alarm failed to motivate him or anyone else to check the engine instruments.

Watching the bootleg animation of the accident, one is struck by a sense of a kind of collective inertia, perhaps brought on, at least in part, by the firm expectation that this would be a routine and uneventful operation. Rather than six separate, independent and active minds, the crew seems to have been reduced to a single torpid one. Only the flight engineer who expressed private misgivings about the flap setting deviated from the collective complacency, but too quietly and too late.

Yet it would be a mistake to suppose that this particular crew was uniquely fumbling and incompetent. Until the accident occurred, this group of pilots and flight engineers was no different from any other. What happened to them could happen to many crews. If we are honest, most of us would privately admit that at one time or another, in the cockpit or elsewhere, we have made some mistake and then failed to detect it in spite of indications that in retrospect seem obvious. Surgeons occasionally remove the healthy kidney and leave the diseased one, and pilots of twin engine airplanes, after an engine failure, have been known to secure the good engine.

This strange accident was the result of several relatively innocuous deviations from standard procedure - the early use of full flap, the sketchy briefing and the initiation of the approach from a lower-than-normal altitude - compounded by a single freak error. Procedures, checklists, CRM, backup systems, warnings and annunciators exist to reduce the chance of such an error occurring, but without a habit of unrelenting and alert attention it never altogether disappears. Pilots need to recognize and distrust the "fat and happy" feeling. As with liberty, the price of safety is eternal vigilance - and a certain amount of good luck.

This article is based solely on the United States Air Force Accident Investigation Board's report of the accident and is intended to bring the issues raised to the attention of our readers. It is not intended to judge or to reach any definitive conclusions about the ability or capacity of any person, living or dead, or any aircraft or accessory.

Peter Garrison taught himself to use a slide rule and tin snips, built an airplane in his backyard, and flew it to Japan. He began contributing to FLYING in 1968, and he continues to share his columns, "Technicalities" and "Aftermath," with FLYING readers.

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