 The growth in Commercial Air Transport ( CAT ) has eroded the operational freedom of GA , both in the air and on the ground at larger airports . <unk> with access to larger airports is compounded by a decline in the number of aerodromes generally , and existing sites are often threatened with closure and re @-@ development for more profitable uses . The UK planning system is designed to focus on local issues , and consideration of the national impact of GA operations is not within its remit . This makes aerodrome development difficult , often <unk> those that successfully negotiate the process to restrictions in use . 
