| HN Mirror

http://www.wired.com/software/coolapps/news/2005/11/69355?cu...

1982 -- Soviet gas pipeline. Operatives working for the Central Intelligence Agency allegedly (.pdf) plant a bug in a Canadian computer system purchased to control the trans-Siberian gas pipeline. The Soviets had obtained the system as part of a wide-ranging effort to covertly purchase or steal sensitive U.S. technology. The CIA reportedly found out about the program and decided to make it backfire with equipment that would pass Soviet inspection and then fail once in operation. The resulting event is reportedly the largest non-nuclear explosion in the planet's history.

1985-1987 -- Therac-25 medical accelerator. A radiation therapy device malfunctions and delivers lethal radiation doses at several medical facilities. Based upon a previous design, the Therac-25 was an "improved" therapy system that could deliver two different kinds of radiation: either a low-power electron beam (beta particles) or X-rays. The Therac-25's X-rays were generated by smashing high-power electrons into a metal target positioned between the electron gun and the patient. A second "improvement" was the replacement of the older Therac-20's electromechanical safety interlocks with software control, a decision made because software was perceived to be more reliable.

What engineers didn't know was that both the 20 and the 25 were built upon an operating system that had been kludged together by a programmer with no formal training. Because of a subtle bug called a "race condition," a quick-fingered typist could accidentally configure the Therac-25 so the electron beam would fire in high-power mode but with the metal X-ray target out of position. At least five patients die; others are seriously injured.

June 4, 1996 -- Ariane 5 Flight 501. Working code for the Ariane 4 rocket is reused in the Ariane 5, but the Ariane 5's faster engines trigger a bug in an arithmetic routine inside the rocket's flight computer. The error is in the code that converts a 64-bit floating-point number to a 16-bit signed integer. The faster engines cause the 64-bit numbers to be larger in the Ariane 5 than in the Ariane 4, triggering an overflow condition that results in the flight computer crashing.

First Flight 501's backup computer crashes, followed 0.05 seconds later by a crash of the primary computer. As a result of these crashed computers, the rocket's primary processor overpowers the rocket's engines and causes the rocket to disintegrate 40 seconds after launch.

November 2000 -- National Cancer Institute, Panama City. In a series of accidents, therapy planning software created by Multidata Systems International, a U.S. firm, miscalculates the proper dosage of radiation for patients undergoing radiation therapy.

Multidata's software allows a radiation therapist to draw on a computer screen the placement of metal shields called "blocks" designed to protect healthy tissue from the radiation. But the software will only allow technicians to use four shielding blocks, and the Panamanian doctors wish to use five.

The doctors discover that they can trick the software by drawing all five blocks as a single large block with a hole in the middle. What the doctors don't realize is that the Multidata software gives different answers in this configuration depending on how the hole is drawn: draw it in one direction and the correct dose is calculated, draw in another direction and the software recommends twice the necessary exposure.

At least eight patients die, while another 20 receive overdoses likely to cause significant health problems. The physicians, who were legally required to double-check the computer's calculations by hand, are indicted for murder.

also http://en.wikipedia.org/wiki/List_of_software_bugs#Military

The software error of a MIM-104 Patriot, caused its system clock to drift by one third of a second over a period of one hundred hours – resulting in failure to locate and intercept an incoming missile. The Iraqi missile impacted in a military compound in Dhahran, Saudi Arabia (February 25, 1991), killing 28 Americans.

A Chinook crash on Mull of Kintyre in June 1994. A Royal Air Force Chinook helicopter crashed into the Mull of Kintyre, killing 29. This was initially dismissed as pilot error, but an investigation by Computer Weekly uncovered sufficient evidence to convince a House of Lords inquiry that it may have been caused by a software bug in the aircraft's engine control computer.

In April 1992 the first F-22 Raptor crashed while landing at Edwards Air Force Base, California. The cause of the crash was found to be a flight control software error that failed to prevent a pilot-induced oscillation.

http://www.computerworld.com/s/article/9183580/Epic_failures...

Osprey aircraft crash

Two weeks before Christmas in 2000, a U.S. Marine Corps Osprey, a hybrid airplane and helicopter, suffered a hydraulic system fault that should have been remedied without loss of life. A hydraulic line broke in one of the two engine cases as the Osprey was shifting from airplane to helicopter mode for landing.

According to the Marine Corps major general who presented reports during the investigation of the incident, the trouble was "compounded by a computer software anomaly." The flight-control computer stopped the rotation of the engine pods when it detected the hydraulic failure.

The pilots went through the normal procedure and pressed the primary reset button to re-engage the pods. At this point, both prop rotors went through "significant pitch and thrust changes," which led to a stall. The plane crashed into a marsh and killed all four Marines onboard.