Aircraft Navigation Systems Quiz

Navigation Systems

• Civilian aircraft may use ground-based TACAN transponders for distance and VOR stations for azimuth. Military use only TACAN for both.
• VORTAC combines VOR and TACAN for both military and civilian use.
• TACAN frequencies are paired with suitable VOR frequencies.
• Civilian pilots select VOR frequency, automatic tuning to TACAN UHF.
• Military pilots select the TACAN channel for automatic tuning.
• Many VORs were colocated with TACANs, becoming VORTACs.
• VOR-DME stations, not equipped for military use, were installed where needed by civil aircraft.
• Area Navigation (RNAV) systems allow for non-airway flight to desired destination.
• Doppler radar measures relative motion, needing initial position input.

Area Navigation

• VORTAC system requires navigating from one VORTAC to another till destination.
• Airports and VORTAC placement restrictions often cause RNAV for longer flight distances.
• IFR flight use creates congestion due to prescribed airways.
• RNAV systems aim to provide direct navigation to destinations from non-airways.
• Doppler radar is an example of an early area-navigation system. This system consists of transmitter, receiver, signal processor and display unit installed inside aircraft.

Course-Line Computer

• CLC enables direct flight from one airport to another using VORTAC and VOR-DME stations.
• CLC calculates aircraft bearing, distance from desired point
• Waypoint electronic creation at destination allows the pilot to navigate to that point through VOR/DME information.
• CLC provides course guidance with a direction indicator (CDI) and distance indicator (DME) using VOR-DME stations.

LORAN

• LORAN, initially developed as a maritime navigation system, is now being adapted for aviation use.
• LORAN system is a hyperbolic system differs from the VORTAC rho-theta navigation system.
• Using LORAN, the pilot plots hyperbolic lines of position to find the aircraft's location.
• LORAN-A wasn't designed for high-speed aircraft.
• Significant time difference between plotting first and second line of position (LOP) introduces inaccuracies.

LORAN-C

• Master station transmits a coded pulse; slave station transmits another coded pulse on same frequency.
• LORAN receiver measures time delay and displays location information on an indicator.
• Plotting of two lines of position (LOP) helps determine position; two different stations provide additional accuracy.
• 100 kHz transmission by master station, identifying chain by group repetition intervals (GRI).
• Slave stations transmit coded signals at the same frequency received from master station.
• LORAN-C receiver determines time differences and plots position coordinates.

Global Navigation Satellite System (GNSS)

• Standard for global navigation services via satellites.
• Provides latitude, longitude, and altitude.
• GNSS receivers determine position using multiple satellites for improved accuracy.
• GPS - the US system is the most operational GNSS.
• Russian GLONASS system will eventually return to full operational status.
• Europe develops Galileo, and China's Compass.
• ICAO designated GNSS as the future navigation system.

Global Positioning System (GPS)

• GPS is the most established GNSS system, used worldwide.
• Twenty four 6 orbital planes satellites, with twenty-one operational and 3 spares are constantly in operation providing global coverage.
• GPS uses satellites as precise reference points for navigation.
• GPS receivers measure distance to satellite and use that calculation for position, speed, estimated time to destination and winds aloft.
• RAIM- Receiver Autonomous Integrity Monitoring verifies satellite signal integrity. Needs at least five satellites visible for calculation.

GNSS Augmentation

• GNSS signals offer accuracy for en route and two-dimensional navigation, not for landing assistance.
• Augmentation systems (GBAS/SBAS) enhance vertical and lateral landing guidance.
• WAAS is a U.S. controlled system used for en route and approach navigation in the U.S.
• WAAS employs ground reference stations for GPS signal signal monitoring and correction.

Inertial Navigational System (INS)

• Precisely measures any change in aircraft direction.
• Utilizes accelerometers to measure changes in aircraft's speed/direction.
• Programming of initial location into the INS computer needed prior to flight.
• INS calculation of course can be determined for flight and estimated time of arrival.
• INS can continuously monitor performance, and alert pilots if required accuracy is not maintained.

Performance-Based Navigation (PBN)

• Developed in 1983, the PBN strategy defines performance parameters rather than specific components.
• Requires aircraft to meet standards with factors including accuracy, integrity, availability, and continuity for specified operations.
• RNP (required navigation performance) specifies navigation requirements.
• Performance based navigation is equipment agnostic. The aircraft's capabilities are the only factor that determine the ability to meet performance requirements for operations.

Instrument Approach Procedures

• Procedures for safe airport arrival when visual approach isn't possible.
• Pilots are responsible for navigation and obstacle avoidance during visual approaches.
• Instrument approach procedures (IAps) are developed in the TERPS manual.
• IAPS are used when the pilot will perform an approach to the runway and landing.