How many satellites are needed for WAAS?

Related questions

1. Is Raim required with WAAS?
2. How does GPS work in aviation?
3. What is Raim in GPS?
4. What does GLS bulb mean?
5. What are the precision approaches?
6. What is a RNP?
7. What is a RNAV in aviation?
8. Is WAAS a precision approach?
9. What is an RNP approach?
10. Is a localizer a precision approach?

Tags

1. #broadcast
2. #satellites
3. #below
4. #those
5. #areas
6. #aircraft
7. #shown
8. #coverage
9. #receiver
10. #surface
11. #covered
12. #regular
13. #geosynchronous
14. #messages