The F-16C uses a variety of navigation methods to direct you to mission locations. Depending on the mission or stage in the mission, you may use different navigation sources. While we have reviewed many of the navigation systems in the Cockpit Controls chapter, this Navigation chapter will review the practical application of these systems.
Embedded GPS/INS (EGI) Navigation
The EGI is the primary navigation system of the F-16C and provides accurate attitude, navigation, and vertical and horizontal steering information. The Up Front Controls (UFC) are the primary interface device to the EGI. In this Navigation chapter we will discuss the practical application of using the EGI for navigation purposes.
INS Alignment
The navigation system can be aligned by a variety of methods on the ground or in the air. This is started by positioning the INS knob on the Avionics Power panel to the desired position. The INS knob is set to NAV when the alignment is complete.
Normal Gyrocompass (NORM) AlignmentThe Normal (NORM) Alignment is the primary alignment mode. The NORM alignment requires approximately eight minutes to fully accomplish.
The Stored Heading (STOR HDG) Alignment allows for a quick alignment in 30 seconds or less in some conditions. This can only be used if the aircraft has been set up specifically for this alignment beforehand.
An Inflight Alignment (INFLT ALIGN) can be performed in flight if GPS data is available. Only limited navigation information is available until the alignment is complete.
The Attitude (ATT)Alignment can be used inflight to restore attitude information if it is lost due to electrical failure. Navigation information is not available until a NORM or INFLT ALIGN is performed.
A full INS alignment in the NORM position should be accomplished prior to every flight. This is normally started just after engine start and avionics power-up to allow time for the full alignment to complete prior to taxi.
1. Position the INS knob to the NORM position. This begins the INS alignment and calls up the INS page on the DED. The progress of the alignment may be monitored from here.
Time Into Alignment.This is the elapsed time in minutes and decimal seconds since the INS alignment began.
Alignment Status. This is an estimate of the alignment quality. Values count down from 99 with the following meanings:
•99 – Initialization
•90 – Valid attitude data, coarse align begins
•79 – Valid heading data
•70 – Degraded navigation state, steady RDY displayed on DED, steady ALIGN displayed on HUD
•60-20 – Estimated position error compared to fully aligned state; 60 = 6.0 times normal, 20 = 2.0 times normal
•10 – INS fully aligned, RDY flashes on DED, ALIGN flashes on HUD
•6 – INS fully aligned and enhanced to 0.6 times normal precision with GPS data or other techniques
Latitude.Latitude of start position.
Longitude. Longitude of start position
System Altitude. Altitude used by the fire control computer for air to ground weapons delivery
True Heading.Last known true heading or heading derived during alignment
Ground Speed.Current ground speed
2. Enter the latitude, longitude and altitude for the starting location.
The last known coordinates and estimate of altitude are displayed when the alignment begins, however the data must be re-entered even if it is still correct.
If the data is accurate, use the DED switch to highlight each line and press ENTR for each in turn.
If the data is not accurate, enter the correct data for each field with the ICP keypad.
Failure to enter the data will flag the alignment as degraded and not allow important monitoring functions to take place. Navigation, weapons delivery and targeting pod pointing errors may also result.
The alignment will stop and start again if the data is entered later than two minutes into the alignment.
3. Monitor alignment progress and switch INS knob to NAV.
The RDY on the DED and ALIGN on the HUD will begin to flash when the alignment is complete. This should happen in 8 minutes or less. Position the INS knob to NAV to accept the alignment.
