The plane crash that killed President Muhammad Zia ul-Haq of Pakistan has spawned myriad conspiracy theories since his C-130 plunged into the Bahawalpur Desert with his top generals and the US Ambassador on board exactly 20 years ago tomorrow.

The despot’s death changed Pakistan’s political landscape in an instant, ushering the Muslim state into a period of shaky civilian rule, similar to the situation the country finds itself in today.

American, Soviet, Pakistani, Indian and even Israeli intelligence agents are among those blamed for sabotaging the plane.

But now, two decades on, the The Times has reviewed the incident and is able to shed new light on what caused the crash, offering a far more simple explanation for the disaster.

The mystery of how Zia died still captures the imagination. A former Pakistani Air Force officer has just published a novel about the dictator’s death, entitled A Case of Exploding Mangoes. In the book, Mohammed Hanif postulates the popular theory that the crew of the aircraft was incapacitated by VX nerve gas smuggled aboard by a Pakistani intelligence agent. Over the years many possible culprits have been identified for the Zia killing, ranging from the ex-Soviet KGB or the Soviet-backed Afghan Government of the time to Pakistan’s arch-rival, India, and even members of General Zia’s own military.

A former US Ambassador to India was relieved of his post after telling Washington that he believed the Israelis, concerned about Pakistan’s nuclear ambitions, were behind the crash. At least one relative of the US military attaché who was killed in the aircraft blames General Zia’s rival, Benazir Bhutto, who was assassinated at the end of last year.

This month, General Hameed Gul, the Islamic hardliner who was head of Pakistan’s Inter Services Intelligence (ISI) spy agency at the time, suggested that the United States might be responsible for murdering its Cold War ally – even though the US Ambassador and military attaché were also killed.

General Gul told The Times that the Pakistani President was killed in a conspiracy involving a “foreign power”.

The Times has uncovered a far less complicated explanation. According to US investigators, a mechanical problem, known to be relatively common with the C-130 military transport aircraft, was to blame. “There were a lot of conspiracy theories and there still are, understandably in that part of the world,” Robert Oakley, who took over as US Ambassador after the crash and helped to handle the politically fraught investigation, told The Times. “

I said [to the Pakistanis]: ‘You are all going to think this is sabotage but I do not have evidence of that . . . We think it’s mechanical failure. We have looked at the records of the US Air Force. We have found a number of failures – maybe 20 or 30 – where C130s behaved this way.” General Zia, Pakistan’s longest-ruling military dictator, was killed when his aircraft crashed minutes after taking off from the southern Punjab city of Bahawalpur on August 17, 1988. Arnold Raphel, the US Ambassador, and Brigadier-General Herbert Wassom, his military attaché, were among 29 other people killed on the flight, including many of Pakistan’s top generals.

Witnesses to the crash cited in Pakistan’s official investigation said that the C-130 began to pitch “in an up-and-down motion” while flying low shortly after take-off before going into a “near-vertical dive” into the desert. General Aslam Beg, who became Chief of Army Staff after General Zia’s death, saw the crash from his aircraft, which had just taken off. Instead of returning to the site he headed straight to Islamabad. His action later caused controversy, leading some to allege his involvement.

He refused to comment when approached by The Times this month. “There is no point talking about the incident after 20 years. There are many more important issues in the country at this point,” he said.

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