US navy Lieut Shane Osborn sat into the cockpit of the American EP-3 surveillance plane at 6.30 a.m. last Sunday morning to set out on what he presumed would be another routine surveillance mission. The four-engine aircraft, packed with some of the world's most sophisticated monitoring equipment, took off from Kadena Airbase on the Japanese island of Okinawa with a crew of 21 men and three women.

The crew included three pilots, one navigator, three tactical evaluators and a flight engineer. Eight cryptographers sat at consoles in the middle and rear of the plane. Their flight path was to take them past Taiwan into the South China Sea. This huge aircraft operates like a giant electronic vacuum cleaner, its monitoring equipment capable of sucking up everything within its field of operation.

As with all similar missions, the job of the highly trained technical crew last weekend was to watch the electronic activity of the Chinese military. The information gleaned would be data-linked to the National Security Agency in Washington, and merged with information from satellite and intelligence sources to form a picture of China's capabilities in the event of conflict breaking out.

Missions like these usually lasted 12 hours and were considered pretty monotonous by the crew. But sometimes that monotony was broken when Chinese aircraft were dispatched to trail the EP-3's movements.

At 8.36 a.m. on Sunday, two Chinese f8 fighter were sent 80 miles south-east of the Chinese Island of Hainan to track the US plane and a game of cat and mouse began. There was nothing new in this. In recent months America had complained to the Chinese that their interceptions on these routine flights were becoming too close for comfort.

What happened next depends on which side you listen to. According to America, its aircraft was over international waters and the Chinese jets were flying directly under the bigger, less nimble US plane. The Navy plane made a turn and a collision occurred.

The Chinese side claims the American aircraft veered into the path of the Chinese jet, causing the collision. The pilot of the stricken Chinese jet, Weng Wai, knew immediately he was in serious trouble. As his aircraft started to descend rapidly, he pushed the ejector button and was released from the jet. The search for Weng Wai, who is now presumed dead, continues.

Realising the propeller and two of the EP-3 engines had been damaged, Lieut Osborn, and his two other senior colleagues, Lieuts Patrick Honeck and Marcia Sonon, had a life-or-death decision to make. Try and limp back to Kadena Airbase or land on Hainan Island.

It was the latter decision which sparked this week's international standoff between the two countries. As they approached Hainan, special emergency procedures for the destruction of secret codes and equipment on board were activated. It is likely that computers disks were wiped and paper shredded. Equipment may have been ejected from the aircraft.

Hainan Island, with its sandy white beaches and jungle-clad hills, is known as the Hawaii of China. It is more used to being invaded by sun-seekers rather than high-powered diplomats and the world's media who arrived this week.

Some 26 minutes after it landed, the American crew was taken into detention. Military experts say there was time enough for the airmen and airwomen to destroy sensitive material.

The US side could have been forgiven for thinking it was an April Fool's joke when they got the news that the EP-3 had landed on Chinese soil after a mid-air collision with a Chinese fighter pilot. It was a plot more suited to a John le Carre novel.

It was several hours before the Chinese and Americans reacted. Xinhua, the official Chinese news agency, did not report the incident for 14 hours. But the blame game got into full swing on Monday with the two sides accusing each other of being responsible for the collision.

In Washington, President Bush cranked things up by saying he was troubled by the Chinese government's inaction. He demanded access to the crew and the plane's return, "without any further tampering".

Three US warships lingered in the South China Sea to monitor the situation. They later moved on. The Chinese made it clear the crew or aircraft would not be returned without an apology.

On Tuesday, the Chinese media were still remarkably restrained in their coverage of the incident. Teams of reporters and camera crews camped around the clock outside the American embassy. An enterprising caterer even set up a noodle stall nearby to keep the hungry journalists fed. Security around the embassy, and in the surrounding diplomatic belt, was extremely tight.

Before midnight on Tuesday, American diplomats were allowed a 40-minute meeting with the plane's crew and all were reported to be in good health. A follow-up meeting was held last night.

On Wednesday President Bush had his second outing on the lawn of the White House to say it was time for the crew to come home. But Beijing wasn't for budging with President Jiang Zemin repeating China's demand for an apology for the incident before he departed on a two-week tour of South America.

The Chinese Foreign Ministry briefings this week were tetchy affairs. One American journalist who asked the spokesman to outline exactly what international laws China claimed the US had broken was told curtly the question was biased.

On the streets, passions were beginning to rise and on Wednesday, the state-controlled media took a much stronger line with banner headlines, anti-US editorials and a picture of the downed plane.

BUT there was no repeat of the scenes witnessed after American NATO planes accidentally bombed the Chinese embassy in Belgrade in 1999. On that occasion, the Chinese leadership was accused by an increasingly impatient Chinese public of not being tough enough with America. The leadership was determined not to make the same mistake this time.

The first sign of a breakthrough in the standoff came on Thursday when US Secretary of State Colin Powell expressed regret at the loss of the pilot and Chinese aircraft. Not enough, the Chinese responded, but a step in the right direction.

The personal expression of regret by President Bush yesterday fuelled speculation that the end was in sight for this row. Yesterday America's old enemy, Vietnam, accused the United States of using human rights to mask a policy of "hegemony", singling out the Sino-US spy plane crisis as the latest example.

"In general, the new US government is trying to make their foreign policy hard, using human rights as cover to carry out hegemony. Where are they going?" the official Communist Party newspaper Nhan Dan said in a back-page commentary.

Both China and America privately agree on one thing this weekend. The mid-air collision between the EP-3 and the Chinese fighter jet is not the issue upon which to go to the wire.

There are more serious matters on the horizon, which have real potential to bring relations between the two to breaking point. In a fortnight, the US administration will decide whether or not to sell sophisticated weaponry to Taiwan. China has voiced its opposition to this move and may be hoping that this week's tough stand on the air collision may serve as a reminder to Washington that Beijing is no pushover.