 These unforeseen events constituted a further major blow to Pan Am, which was still reeling from the 1988 Lockerbie disaster.To shore up its finances, Pan Am sold most of its routes serving London Heathrow – arguably Pan Am's most important international destination – to United Airlines.This left Pan Am with only two daily London flights, serving Detroit and Miami, which used Gatwick as their London terminal from the start of the 1990/91 winter timetable.