What does the Wide Area Augmentation System (WAAS) primarily enhance?

The Wide Area Augmentation System (WAAS) primarily enhances GPS navigation by improving the accuracy, integrity, and availability of GPS signals for aviation use. It does this through a network of ground reference stations that monitor GPS satellite signals. Any errors in these signals are detected and corrected, and the corrected signals are then broadcast to users via geostationary satellites. This results in a significant increase in the precision of navigational data, allowing aircraft to fly more accurately and safely, particularly during approaches and landings in low-visibility conditions.

The other options do not align with the primary function of WAAS. Ground control systems typically refer to terrestrial navigation and control, aerial rescue operations focus on emergency response and recovery, and aircraft thrust management deals with engine performance and control rather than navigation.