GPS Navigation Changes
With the January 1, 2020 deadline for ADS-B out certification just around the corner, pilots will be required to assess how their GPS Navigation position reporting avionics will perform PRIOR to takeoff for flights within U.S. airspace that currently requires a Mode-C transponder. The FAA is specifically targeting GPS receivers that are not WAAS compatible and will require pilots to check along their entire filed flight plan route.
This sounds a little complicated, but the FAA says pilots can use a “service availability prediction tool” (SAPT) to verify that their GPS receivers meet the navigation integrity category (NIC) performance requirements that are used to define the accuracy of the performance reporting equipment. NIC refers to the containment radius around an aircraft’s reported position. The reported position must be within 0.2 NM of the actual position for a good test.
Using the SAPT creates a record of the check for legality purposes, but the test must be done less than 24 hours from the departure time. A satisfactory prediction result means the flight is legal to go. If, however, the GPS status changes once the aircraft is airborne, the pilot will not be held accountable. For example, if an unexpected government interference test is run or if the flight has to divert due to weather or mechanical issues, the pilot is not responsible if the aircraft enters an area of GPS unreliability.
For more information on how to use the SAPT, visit the FAA website at https://sapt.faa.gov/default.php. GPS Navigation is only as good as the accuracy of our equipment. A quick test before departure is a simple way to keep you safe (and legal).