Original sentence: The Vulcan used entirely powered control surfaces, this combined with the relatively small space for the flight crew meant that a fighter-like stick could be used instead of a control column with the added benefit that ejection could be quicker in an emergency.These had little capacity in event of a power loss so the system was revised for the Mark 2 to use a Ram Air Turbine (RAT) that would operate at higher altitude and an Airborne Auxiliary Power Unit (AAPU) which could be started once the aircraft had reached a lower altitude -  or less
Edited sentence: The Vulcan used entirely powered control surfaces; this combined with the relatively small space for the flight crew meant that a fighter-like stick could be used instead of a control column, with the added benefit that ejection could be quicker in an emergency.These had little capacity in event of a power loss, so the system was revised for the Mark 2 to use a Ram Air Turbine (RAT) that would operate at higher altitude and an Airborne Auxiliary Power Unit (AAPU) which could be started once the aircraft had reached a lower altitude of  or less