Complex sentence: Fixed wing aircraft have generally been replaced by the more versatile police helicopter since the 1940s, however aeroplanes still have their uses in some areas, such as border patrol, as their higher speed and greater operating altitude allows larger areas to be covered.
Split into simpler sentences: Fixed wing aircraft have generally been replaced by the more versatile police helicopter since the 1940s. However, aeroplanes still have their uses in some areas, such as border patrol, as their higher speed and greater operating altitude allows larger areas to be covered.