POSITION INITIALIZATION AND INDEPENDENT POSITION MONITORING
Position preparation concerns both the initial reference and the subsequent credibility of the navigation solution. The older guide illustrates a particular IRS-entry arrangement; the installed Fenix standard may present a different interface. Use the loaded unit's actual position/alignment functions. This chapter therefore specifies the information and required result without manufacturing a modern IRS INIT or ALIGN confirmation sequence from an older panel illustration. [66, PDF pp. 106-107,486-496]
1. Establish the real starting position. With the aircraft stationary at the stand, compare the available position reference with the actual parking location. An airport reference coordinate can be valid database information while lying away from the stand. Check latitude, longitude and hemisphere if inspecting or entering coordinates. A sensible airport name cannot reveal a wrong hemisphere or a coordinate taken from another saved session. [66, PDF pp. 106-107,486-496]
2. Establish alignment state. Confirm the appropriate normal NAV selections on the installed reference panel and follow its actual alignment indications. The illustrated CDU/keypad panel reads IR1, IR3, IR2 from left to right; unit numbers take priority over a presumed sequential arrangement. A simulator alignment-speed option changes the duration, not the need for a credible initial position and valid resulting references. [66, PDF pp. 106-107,486-496]
3. Inspect the developed solution. Use the available POSITION MONITOR and IRS/GPS monitor information to compare the contributing references and FM positions. Read the labels and validity states, not just whether coordinates are displayed. A monitor page is useful because it exposes sources that an apparently tidy moving map can otherwise conceal. Identify what is being compared before deciding whether a numerical difference is significant. [66, PDF pp. 106-107,486-496]
4. Add an independent geometry check. Enter a known reference on PROG BRG/DIST and compare its bearing/distance with the actual location and suitable raw navigation indications where available. The reference is a monitoring selection, not DIR TO. Keep great-circle distance to that reference separate from remaining distance along the route. Choose a reference whose location and identity are actually known. [66, PDF pp. 106-107,486-496]
5. Investigate discrepancies before changing position. Confirm the selected identifier and raw aid, alignment/validity state and actual aircraft position. The source describes exceptional manual position updating; it does not justify routinely overwriting the FM position to make two pictures coincide. Follow the applicable current procedure if the reference is invalid. In a simulator investigation, retain the evidence needed to distinguish a programming error from a navigation-state issue. [66, PDF pp. 106-107,486-496]