Pan Am Flight 103 (Lockerbie bombing)

On December 5, the U.S. Federal Aviation Administration (FAA) issued a security alert stating that on the same day a man with an Arab accent had called the U.S. Embassy in Helsinki and announced that within the next two weeks a Pan Am flight from Frankfurt to the U.S. would be blown up by members of the Abu Nidal organization; a Finnish woman would unknowingly carry the bomb on board. In the end, the caller was off by two days with his timing.

The warning was taken seriously by the US government. The State Department sent the security message to dozens of embassies. The FAA sent it to all airlines, including Pan Am, which responded by charging each passenger a five-dollar security surcharge and promising a security plan that would screen passengers, employees, airport facilities, baggage, and aircraft with unrelenting thoroughness. The security team at Frankfurt did not find the message among a stack of papers until a day after the disaster. In addition, a Frankfurt security employee responsible for detecting explosives under X-ray reported that she was unaware of the Semtex explosive used until she was interviewed by ABC eleven months after the attack.

On 13 December, the warning was published in the US embassy in Moscow and also passed on to all US citizens staying there, including journalists and business people. This led some to rebook on flights operated by other airlines. The seats now vacant on PA103 were filled at short notice from the waiting list.

PA103, for Pan Am Flight 103, was the flight number of Pan Am's third daily transatlantic flight at the time from London Heathrow Airport to Kennedy Airport in New York. On 21 December 1988, the route was flown by a Boeing 747-121 with aircraft registration N739PA and the nickname "Clipper Maid of the Seas".

The daily service PA103 started already in Frankfurt with a Boeing 727 for the route to Heathrow. It was a quirk of the airlines Pan Am and TWA at the time to offer different flights under the same flight number. Flight PA103 could be booked as a direct Frankfurt-New York connection, although it was necessary to change planes in London. 47 of the 89 passengers on the first leg of PA103 transferred there to the Boeing 747, which was to continue the flight to New York. The 747 had arrived that morning as flight PA124 from San Francisco and was parked in parking bay K-14 at Terminal 3. During its two-hour stay, the aircraft was guarded by Pan Am's security company, Alert Security.

The jumbo jet carried 243 passengers and 16 crew members on its final flight, with pilots Captain James MacQuarrie and First Officer Raymond Wagner and Flight Engineer Jerry Avritt in the cockpit. Britain's Mary Geraldine Murphy (51) was assigned as chief stewardess. The cabin crew based at Heathrow also included: Siv Ulla Engström (51), Elisabeth Nichole Avoyne-Clemens (44), Noëlle Lydie Campbell-Berti (41), Elke Etha Kühne (43), Maria Nieves Larracoechea (39), Irja Syhnove Skabo (38), Paul Isaac Garrett (41), Milutin Velimirovich (35), Lilibeth Tobila Macalolooy (27), Jocelyn Reina (26), Myra Josephine Royal (30), and Stacie Denise Franklin (20). The flight attendants on flight PA103 were from ten nations in Europe and the United States. The cabin crew members had between nine months and 28 years of service with Pan Am.

The last contact with flight 103

The flight took off from runway 27L at 6:25 p.m. after a 25-minute delay, after which the plane departed Heathrow in a northwesterly direction on the so-called Daventry departure route. After the Boeing 747 left the airport behind, the pilots headed north towards Scotland. At 6:56 p.m., the aircraft reached the border and had reached its cruising altitude of 9,400 meters here. Captain MacQuarrie throttled back to cruising level, as planned.

At 7pm PA103 was taken over by the Scottish Airspace Surveillance Centre at Prestwick, where clearance had to be obtained for the flight over the Atlantic. As they entered Scottish airspace, Alan Topp, the controller in charge, made contact with the pilots.

Captain MacQuarrie replied, "Good evening Scottish, Clipper one zero three. We are at level three one zero." (Good evening Scottish (short for "Scottish Control"), Clipper one zero three. We are at flight level three one zero).

Then Copilot Wagner said, "Clipper one zero three, requesting oceanic clearance." (Clipper one zero three, requesting oceanic clearance.)

This was the last sign of life from aboard the 747.

The explosion

At 19:01, Scottish air traffic controller Alan Topp saw PA103 approach the corner of the Solway Firth and pass over its north coast at 19:02. The aircraft was shown as a small green square with a cross in the middle and the transponder code on the radar screen, the code was 0357. In addition, Topp was shown vital information about the aircraft's course, altitude and speed. The last overlay on his screen, received from the 747, showed him that it was on course 316° and flying at a speed of 580 km/h (313 kts CAS). Analysis later carried out by Scottish authorities showed a heading of 321° and a speed of 804 km/h (434 kts ground speed).

Around this time, the aircraft was destroyed by an explosion of 340 to 450 g of plastic explosive at an altitude of about 9,400 m above the village of Lockerbie in Dumfries and Galloway, Scotland. The explosion tore a 0.5 m wide hole in the left side of the fuselage, a few meters below the P in the Pan Am lettering.

Inside the aircraft, the force of the explosion shattered the thin wall between the front cargo hold and a space in front of it in the direction of flight. This room contains, among other things, electronic equipment connected to navigation and communication systems in the cockpit. The explosion also destroyed some of these systems. The front part of the fuselage began to move uncontrollably. These strong movements caused the remaining connecting pieces to the rest of the fuselage to break and the complete front part broke away.

At the same time, direct blast waves from the explosion hit waves already reflected from the rear hull. This resulted in further damage to the fuselage. Part of the roof above the explosion site was torn away. The force of the explosion was further amplified by the abrupt equalization of the prevailing pressure differential between the interior of the aircraft and the surrounding area. Inside the pressurized cabin, the pressure was about four times higher than outside the aircraft.

The disintegration of the plane was very fast. Investigators from a British agency said that the nose of the plane (nose section with cockpit) separated from the rest within three seconds of the explosion, taking one of the four engines with it. The fuselage along with the wings continued to fly until it had descended to an altitude of 6,000 meters. From this point it fell almost vertically to the ground. In free fall, the fuselage broke apart into smaller pieces.

At 7:02 p.m. and 47 seconds, PA103 disappeared from the radar screen. Topp tried to reach Captain MacQuarrie and asked a nearby KLM flight to do the same, but both attempts were unsuccessful. At first Topp thought the plane had entered what is known as a zone of silence, a "dead" area from which no or faulty radar signals can be received. Where one green square had previously lit up on the radar screen, four now appeared, and after a few seconds the squares began to disperse further. A comparison of the flight recorder with the radar records showed that after only eight seconds the wreckage already had a dispersion of 2 km.

Of the fuselage sections, the first to hit - about a minute after the explosion - was the wing section, carrying 91,000 kg of fuel and travelling at 825 km/h, in Sherwood Crescent, a district of Lockerbie. A seismograph nearby detected a tremor measuring 1.6 on the Richter scale. The kerosene ignited and the huge fire destroyed several homes. The fire was so intense that nothing remained of the left wing. Based solely on the number of bolts found, it was later found that both wings had hit there.

Even the British Airways pilot flying nearby, Captain Robin Chamberlain, radioed Topp that he could see a large fire on the ground. Meanwhile, the destruction continued on Topp's screen, which was now full of bright squares, all moving eastward with the wind.

Immediately before the explosion, the plane had flown over the Chapelcross nuclear power station, which is 16 kilometres south of Lockerbie. Since the Chernobyl nuclear disaster had occurred only two years earlier, many Lockerbie residents initially thought there had been a meltdown at the power plant.