Complex sentence: The first jet aircraft in the BKS fleet were two Hawker Siddeley Tridents, acquired in April 1969, which were flown on the Newcastle-Heathrow schedule and also on inclusive tour charters from Newcastle and London to Mediterranean destinations.
Split into simpler sentences: The first jet aircraft in the BKS fleet were two Hawker Siddeley Tridents, which were acquired in April 1969. These served the Newcastle-Heathrow route, as well as on inclusive tour charters from Newcastle and London to Mediterranean destinations.