[The following account is taken from the Wikipedia article Pan Am Flight 103.]
On 29 September 1989, President [George H W] Bush appointed Ann McLaughlin Korologos, former Secretary of Labor, as chairwoman of the President's Commission on Aviation Security and Terrorism (PCAST) to review and report on aviation security policy in the light of the sabotage of flight PA103. Oliver "Buck" Revell, the FBI's Executive Assistant Director, was assigned to advise and assist PCAST in their task. Mrs Korologos and the PCAST team (Senator Alfonse D'Amato, Senator Frank Lautenberg, Representative John Paul Hammerschmidt, Representative James Oberstar, General Thomas Richards, deputy commander of US forces in West Germany, and Edward Hidalgo, former Secretary of the US Navy) submitted their report, with its 64 recommendations, on 15 May 1990. The PCAST chairman also handed a sealed envelope to the President which was widely believed to apportion blame for the PA103 bombing. Extensively covered in The Guardian the next day, the PCAST report concluded:
"National will and the moral courage to exercise it are the ultimate means of defeating terrorism. The Commission recommends a more vigorous policy that not only pursues and punishes terrorists, but also makes state sponsors of terrorism pay a price for their actions."
Before submitting their report, the PCAST members met a group of British PA103 relatives at the US embassy in London on 12 February 1990. Twelve years later, on 11 July 2002, Scottish MP Tam Dalyell reminded the House of Commons of a controversial statement made at that 1990 embassy meeting by a PCAST member to one of the British relatives, Martin Cadman: "Your government and ours know exactly what happened. But they're never going to tell." The statement first came to public attention in the 1994 documentary film The Maltese Double Cross – Lockerbie and was published in both The Guardian of 29 July 1995, and a special report from Private Eye magazine entitled "Lockerbie, the flight from justice" May/June 2001. Dalyell asserted in Parliament that the statement had never been refuted.
[And the following account is from the Canadian Attic blog.]
A US presidential commission issued a report on the December 1988 of a Pan American jetliner over Lockerbie, Scotland that had killed all 259 people aboard and 11 more on the ground. The commission said that it was not certain how the bomb was smuggled aboard the plane, but cited evidence that it was an unaccompanied suitcase loaded in Frankfurt, West Germany. The report said that the security system for US civil aviation "is seriously flawed and has failed to provide the proper level of protection to the traveling public." The commission called for greatly increased security at US airports, the creation of the post of assistant secretary of transportation for security and intelligence, and establishment of a national system for warning passengers of credible threats against airlines or flights.