You will be given a definition of a task first, then some input of the task.
In this task, you will be given a passage to read. A fill in the blank question will be given to you.  Your answer should fit the blank appropriately.

  Airspace is shared by CAT , military and GA users . It is divided into controlled airspace , in which aircraft must always be under the control of an air traffic controller , and uncontrolled airspace , in which aircraft can operate autonomously . Although GA flights can under certain conditions enter controlled airspace , they operate mainly outside of it . Controlled airspace is essential for the provision of a known air traffic environment necessary for the safe operation of CAT . A CAA review found that  mixing [ commercial ] operations with other users is considered undesirable , even untenable by commercial operators . However this position has resulted in extensive Class A controlled airspace with complex boundaries , including some running down to the ground , prohibiting VFR access to airspace , resulting in high numbers of GA flights operating close to the borders of controlled airspace who could not get formal receipt of an air traffic service . Coupled with pilot navigation errors , hundreds of airspace infringements have been recorded every year . Increases in the number of CAT operations , and in the number of airports they operate from , has resulted in a corresponding increase in Class A controlled airspace . Between 1997 and 2006 this area grew in size from 13 per cent of all airspace to 22 per cent nationally , and from 24 per cent to 43 per cent in airspace above England and Wales , leading to a perception within the GA community of being squeezed out . There are particular problems for GA around large airports , where Class A controlled airspace extends to ground level . The concentration of commercial operations and high demand for GA in the South East of England have also resulted in extensive areas of Class A controlled airspace there , which serve to channel uncontrolled GA operations through high @-@ collision @-@ risk hot spots . fill in the blank  : Airspace is shared by CAT , military and __________________ users . 
Output:
 GA 