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Route Study

in Flight Planning

Flight Planning

During flight planning, crewmembers should conduct a route study. For the navigator, a route study encompasses three phases of flight: takeoff and climb, cruise, and approach and landing.

Takeoff and Climb

Before completing pre-flight planning, be familiar with the departure procedure filed. Check the NAVAIDs, such as tactical air navigation (TACAN), very high frequency (VHF) omnidirectional range (VOR), and automatic direction finder (ADF) to be used on the departure procedure. Note magnetic headings, radials, or bearings and altitude restrictions.


During takeoff and climb, the navigator’s duties include monitoring the departure procedure, copying clearances, and ensuring applicable altitude restrictions and terrain clearance are maintained.

Estimated Times of Arrival (ETA)

During climb-out, controlling authorities may request estimated time of arrivals (ETAs), and generally it is the navigator’s duty to compute these ETAs. Use the best source of groundspeed to compute ETAs. As a backup, use the inertial navigation system (INS), flight-planned GS, or TACAN distance measuring equipment (DME) change for groundspeed. When a controlled time of arrival is required, the navigator should compute an IAS or TAS for the pilot to maintain when approaching cruise altitude.

Navigator’s Duties

While the primary duty is to monitor and direct the progress of the aircraft, the navigator must meet many associated requirements, such as completing the log, filling out forms, working controlled ETAs, and analyzing the information received from the navigation equipment.


The navigator’s log is usually the only record of the aircraft’s actual position at any given time during the flight. For this reason, it must be accurate and complete. Log procedures vary between organizations; however, the basic log requirements and purpose remain the same—to keep an accurate record of data for the navigator’s reference and debriefing purposes and to serve as a worksheet for the navigator. Generally, required items for log entry are all information necessary to reconstruct the flight.

Celestial Precomps

Like logs, celestial precomp forms also vary between organizations. Like the log, the computational format may vary; however, the celestial computations themselves are essentially the same.

Approach and Landing
Standard Approaches

The descent portion of the flight is similar to the climb portion. Instrument approach plates are established for almost all airfields of any significance in the world. The published approaches are normally flight-checked for safety of flight; if not, they are appropriately annotated. The navigator must make certain that the route affords adequate terrain clearance given by the approach control. Because of congested air traffic, approaches must be followed precisely. The navigator should monitor the aircraft position and altitude during descent and advise the pilot of any deviations.

Airborne Radar Approach (ARA)

In-flight duties for the navigator are many and diverse. As it is true that pilots earn their money on takeoffs and landings, navigators earn their money during the cruise portion, but they are also responsible for monitoring the departure and approach. Since crew safety and flight accomplishment are affected by each crewmember’s performance, the success of any flight depends in part on the navigator’s competence. Conscientious performance of in-flight duties can avert embarrassing and dangerous situations for the entire crew.


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