What navigation backup methods may be used after GPS loss?

What navigation backup methods may be used after GPS loss?

• A. VOR, DME, INS, IRS
• B. VOR, DME, GPS
• C. INS, IRS
• D. DME, GPS

Answer: (A)

When GPS is unavailable, you rely on navigation methods that don’t depend on satellite signals. VOR provides a magnetic bearing to a ground-based station, and DME gives your distance from that station. Together they let you determine your position and track on established airways and fixes. The Inertial Navigation System (INS) or Inertial Reference System (IRS) uses internal accelerometers and gyros to compute your position and velocity without any external signals. This combination gives redundancy: radio navigation helps fix your position relative to known beacons, while inertial navigation keeps you airborne and estimating position when signals are limited or degraded. Relying on GPS again or omitting one of these backup methods would reduce reliability, so using VOR/DME along with INS/IRS is the robust set of backups after GPS loss.

When GPS is unavailable, you rely on navigation methods that don’t depend on satellite signals. VOR provides a magnetic bearing to a ground-based station, and DME gives your distance from that station. Together they let you determine your position and track on established airways and fixes. The Inertial Navigation System (INS) or Inertial Reference System (IRS) uses internal accelerometers and gyros to compute your position and velocity without any external signals. This combination gives redundancy: radio navigation helps fix your position relative to known beacons, while inertial navigation keeps you airborne and estimating position when signals are limited or degraded. Relying on GPS again or omitting one of these backup methods would reduce reliability, so using VOR/DME along with INS/IRS is the robust set of backups after GPS loss.