Instrument Rating Checkride Practice Test

How does WAAS improve GPS accuracy?

1. By increasing the number of satellites

2. By monitoring ground reference stations for corrections

3. By providing real-time weather updates

4. By directly communicating with aircraft

The correct answer is: By monitoring ground reference stations for corrections

WAAS, or Wide Area Augmentation System, enhances GPS accuracy by using a network of ground reference stations that monitor GPS signals. These reference stations are strategically located across a wide area and are used to detect any errors in the GPS signals based on their known positions. When discrepancies are identified, the system calculates corrections, which are then uplinked to geostationary satellites. These satellites broadcast the corrections to users on the ground and in the air, allowing them to receive a more accurate positioning solution. This method significantly reduces errors caused by various factors, such as satellite clock drift and atmospheric conditions, ultimately improving the precision of GPS navigation and providing accuracy that can reach within one to two meters. Other options, such as increasing the number of satellites or providing weather updates, do not directly contribute to the enhancement of GPS accuracy in the way that WAAS operates. Similarly, while communication between WAAS and aircraft is involved, the key improvement comes from the corrective data generated by the ground reference stations.