On February 23, 2008, at roughly 10:30 a.m. local time on the island of Guam, one of the vital powerful aircraft on the planet was in serious trouble. Moments after takeoff, the B-2 Spirit stealth bomber often called Spirit of Kansas baffled the 2 pilots within the plane’s cockpit because it began to inexplicably descend back to Earth. The crew struggled in an try and regain control of the doomed bomber, but its left wing clipped the runway and each pilots were ejected—one suffered a spinal injury, but thankfully, there have been no casualties.
The incident was over in a matter of seconds, but it surely left behind a $2 billion receipt, making it the costliest airplane crash in history. A B-2, able to leveling entire cities and wreaking apocalyptic destruction, had been brought down by nothing greater than an easy change within the weather. The crash would prove that, despite all of humankind’s power, Mother Nature at all times has the last word.
Flight Home, Interrupted
Everyone involved knew the flight was going to be a protracted one. The B-2 bomber often called Spirit of Kansas had spent 4 months on the island territory of Guam. As a part of U.S. Pacific Command’s Bomber Forward Presence mission, 4 B-2s had been deployed to Andersen Air Force Base as a deterrent to North Korea and China. For the 4 bomber crews and the maintainers that had followed them from Whiteman Air Force Base in Missouri, February 23 was the day they got to go home.
The plane was scheduled to take off that morning as a part of a two-ship formation with one other bomber. The flight back home to Missouri was set to be a grueling one, greater than 16 hours long and involving two aerial refuelings. The 2 pilots loaded their personal equipment, classified information, and “long duration crew comfort equipment”—once described by a B-2 pilot as reclining beach chairs for sleeping—aboard the aircraft. The crew began the engines and commenced working through their preflight checklists.
Once each pilots and ground crew were satisfied the plane was ready, the B-2 taxied to a position on Andersen’s runway. Unknown to the pilots and the B-2’s computer brain, Guam’s high humidity had caused the plane’s Air Data System to receive faulty information. The plane’s altitude on the bottom read as 682 feet—a difference of 136 feet from the true ground elevation—however the crew, on temporary project from Missouri, didn’t know any higher and didn’t catch the error.
Because the plane began rolling down the runway, the cockpit Master Caution Light illuminated together with a Flight Control System warning light—then they each disappeared six seconds later. The co-pilot investigated the difficulty and quickly concluded the fault had cleared; the plane was still go for takeoff. Twenty-one seconds later, the pilot initiated takeoff, pulling the plane’s nose right into a climb.
What the pilots did not know was that the plane’s Port Transducer Units (PTUs), the identical sensors that had generated bad altitude data, were also misreporting the plane’s air speed. The PTUs dutifully reported the plane rolling down the runway at 163 miles per hour, a secure takeoff speed, as an alternative of 151–154 miles per hour—not a secure takeoff speed.
Because the bomber’s wheels lost contact with the bottom, the B-2’s automatic Flight Control System (FCS), acting on faulty data, believed the plane was actually in a steep dive. With a purpose to avoid what it believed to be an imminent crash, the FCS initiated a steep “nose-up” 30-degree climb—an motion that guaranteed a crash. The plane’s low speed, heavy, fuel-laden weight status, and momentum couldn’t sustain a climb, and the plane began to sink. Pilot No. 1 tried to regain control of the aircraft, but it surely was “unrecoverable,” in keeping with the accident report. The bomber’s left wingtip struck the runway and the pilots immediately ejected, leaving the plane to sink to the bottom, crash, and burn.
Air base personnel swiftly recovered the 2 pilots. Pilot No. 1 received only minor injuries, while Pilot No. 2 suffered compression fractures in his spine consequently of the ejection process, eventually making a full recovery. The wreckage of the previous Spirit of Kansas burned for six hours, and bits of aircraft were spread over a field of greater than 4 acres.
What Went Fallacious
An investigation of the accident laid the blame on faulty data leading the Flight Control System to make flawed decisions. Like many modern aircraft, the B-2 is a “fly-by-wire” aircraft that uses flight computers and an electronic interface as an alternative of traditional mechanical flight control systems. The flight system makes decisions on how the plane should fly based on data pulled from sensors across the aircraft, including environmental systems corresponding to the Port Transducer Units (PTUs). Like several decision-making process, the ultimate call is just nearly as good as the data it’s based on.
The B-2 was equipped with 24 PTUs that allowed the pc system to calculate airspeed, angle of attack, sideslip, and altitude. Guam’s high humidity had allowed moisture to build up within the plane’s PTUs, leading to the units generating faulty environmental data. That data biased the pc system into an early takeoff before the plane was fast enough to sustain lift, then led it to conclude it was in a steep dive when it was actually gaining altitude. A crash was inevitable.
The accident investigation laid the blame on the humidity and the PTUs and exonerated the pilots of any wrongdoing. It also emerged that maintainers on an earlier 2006 deployment to Guam had noticed bad PTU data. Engineers advisable pilots activate the PTU’s built-in heaters to dry them out before the FCS could pull data from them. That suggestion was never formalized and was never passed on to subsequent bomber deployments. Because of this of the crash, the Air Force added activating the PTU heaters before takeoff to the usual preflight procedures.
The bomber was a complete write-off, and what remained of the plane was cut up and sent to Edwards Air Force Base in California for evaluation. In today’s dollars, the B-2 Spirit would cost roughly $2 billion dollars. While the U.S. Air Force was accustomed to losing multi-million dollar aircraft, this was the primary—but probably not the last—multi-billion dollar crash.
The Takeaway
No one likes humidity, including B-2 bombers. If the B-2 fleet had remained at their home base in Missouri and never deployed overseas, the 2008 Guam crash would likely never have happened. That said, the U.S. military is a worldwide expeditionary force that have to be prepared to operate anytime, anywhere—in jungles, deserts, frozen tundras, and more. If crews and maintainers fail to maintain a watchful eye on their equipment as conditions change, routine missions could end in disaster.
The crash was a $2 billion lesson in how even essentially the most high-tech of apparatus may be brought down by nothing greater than the local weather.