 Most mid-size business jets have less than of cabin space.The ceiling allows people to comfortably stand, and because of the aircraft's size and defensive equipment, this is the aircraft that is the first choice for domestic or European trips.It was also announced in the Strategic Defence and Security Review 2015 that the current Command Support Air Transport fleet aircraft would be replaced as they reached the end of their life to increase their operational utility and ensure continued effective transport for the Royal Family and senior ministers.