Security surrounding the flight from Tripoli is tight, so only when the jet lands will the world known for sure that the Libyan leader, Colonel Muammar Gaddafi, has kept his word to hand over the two men.
Jim Swire, a representative of the families of British victims, whose daughter died in the bombing, is sure that Colonel Gaddafi will fulfil his pledge.
"A hard-nosed criminal trial is the best option to find out why our loved ones died," he said. He said the handover would represent a successful outcome for the families determination to get a trial. "It ends a 10-year emotional roller- coaster ride," Dr Swire said.
The man in charge of the transportation and handover of the suspects is Hans Corell, a UN legal officer. He leaves for Tripoli today and, if all goes according to plan, he will return with the accused men, Abdel Basset Ali al-Megrahi and Lamen Khalifa Fhimah.
On arrival, the Libyans will give themselves into the custody of Dutch police officers and be taken to a safe house in Amsterdam. The formal process of extradition then begins, to transfer Messrs Megrahi and Fhimah to the custody of Scottish police officers and take them to Camp Zeist, a former air base near The Hague. The base has been deemed Scottish territory for the trial. There the two men will be charged with killing 270 people, mostly Americans and Britons, aboard Pan Am flight 103 and in Lockerbie, Dumfries and Galloway.
The Scottish detectives who investigated the disaster say they have compelling evidence that the two men arranged for a suitcase containing a bomb to be loaded on to the flight. The suspects are accused of being Libyan intelligence agents. Both men deny the charges.
Once Mr Megrahi and Mr Fhimah are in the Netherlands, the UN secretary- general, Kofi Annan, is to write a letter to the Security Council that would suspend sanctions imposed on Libya in 1992. The complete cessation will be a formality at the next full UN meeting.
Much of the seven years since sanctions were imposed was lost in a diplomatic stalemate as the UN tried to find a way for the trial to be held in a Scottish court. The Libyans did not believe the men could get a fair trial in either Britain or the United States. Then, last summer, Robin Cook, the Foreign Secretary, persuaded the US to agree with Libya's often-stated willingness to accept a trial in a "neutral" venue.
Colonel Gaddafi accepted the Netherlands as the venue but problems remained, including where the men would serve their sentence if they were convicted. Those outstanding issues have been resolved. It has been agreed that any sentence imposed would be served in Barlinnie Prison in Scotland.
It has taken another seven months to make the handover possible. The greatest credit for this must go to President Nelson Mandela of South Africa, who has undertaken several journeys to Libya at the request of the Lockerbie victims' families. It was Mr Mandela and Saudi King Fahd, who on a visit to Tripoli on 19 March, persuaded Colonel Gaddafi to agree the deadline of 6 April.
President Mandela's role as honest broker and guarantor was the clincher for Colonel Gaddafi and overcame his deep suspicion of Anglo-American double dealing. Last week the Libyan leader reasserted that the men were to be delivered to the court by the deadline.
The Libyan news agency Jana said: "Mandela confirmed to brother leader Gaddafi that things were going as desired and in accordance with the agreement with the United Nations over the Lockerbie issue."Reuse content