This paper gives an account of the engineering and operational aspects of the introduction and first three years' operation by British European Airways of the first propellerturbine engine to go into airline service—the Rolls-Royce Dart which powers the Vickers Viscount air liner. The origin of this type of gas turbine engine and its chief advantages and disadvantages are considered. The main features and operational characteristics of the Dart engine are detailed. The training, operational handling, flight planning and maintenance aspects of the introduction and operation of the Dart engine in the Viscount are reviewed, and the experience accumulated is summarised. It is noted that apart from all the new ground that has had to be covered and all the associated development, no special problems have been encountered. Considerable advantages in respect of engineering and operational simplification have been demonstrated. Experience indicates that this type of engine has good reliability and long overhaul life characteristics, and confirms its general suitability for medium-speed air transportation. The paper ends with mention of some of the probable trends of propeller-turbine development, and with suggestions for some additional improvements which the author considers would benefit civil operators.