ADIRS: ALIGNMENT, POSITION AND USABLE REFERENCES
Air-data and inertial-reference functions supply different parts of the instrument and navigation picture. Air data includes pressure-derived altitude, airspeed and temperature information; inertial information includes attitude and motion used by the displays and navigation systems. A valid indication depends on the relevant reference being available, not merely on a screen having powered up. [65, PDF pp. 3–5]
Select the three IR selectors to NAV using the loaded panel's actual arrangement and keep the aircraft stationary during alignment. Compare the initial position with the aircraft's stand. The airport reference point can be a legitimate database position without being the place where this aircraft is parked; position entry and position verification remain separate checks. [65, PDF pp. 6–8] [66, PDF pp. 102–112]
Judge completion from the alignment indications and resulting flight-display information. A simulator option that shortens alignment does not remove the need for a valid position. ATT provides attitude-reference operation for a different situation; it does not replace normal navigation alignment. Continue other parked preparation while the selected sequence completes. [65, PDF pp. 6–7]
ADIRS CDU/keypad option: IR1 left, IR3 centre, IR2 right. [63, PDF p. 1]
A320 air-data probe locations on the actual nose profile. [65, PDF p. 4]
IN PRACTICE: ADIRS: verify alignment and position
Before you begin: Stable electrical supply and the aircraft stationary. Use the actual ADIRS/GNADIRS standard fitted to the loaded Fenix aircraft; identify selectors by their printed unit numbers.
1. Identify all three units
Action. Read the IR unit labels on the installed overhead panel. Set all three mode selectors to NAV for normal preparation, checking each printed unit number rather than relying on a remembered left-to-right order.
Check. Each intended unit is selected to NAV. A different panel arrangement has not led to a missed selector. [65, PDF pp. 6-8] [23, PDF pp. 1012,1014]
2. Observe the alignment state
Action. Read the alignment indications provided by the installed units and keep the aircraft stationary. Note any fault or alignment-related message that requires attention before proceeding.
Check. Alignment is progressing in a known state. A fixed time borrowed from another setup has not replaced the actual indications. [65, PDF pp. 3-5] [65, PDF pp. 6-8]
3. Check the initialized position
Action. Compare the position reference used by the MCDU/ADIRS with the aircraft’s actual location and stand. Complete the installed unit’s required confirmation only through its actual interface.
Check. The position reference is credible. The older manual’s ALIGN IRS key sequence has not been assumed to be the interface of every Fenix configuration. [66, PDF pp. 106-107]
4. Check usable references
Action. After alignment, inspect attitude and heading on both primary flight displays and the navigation displays. Include the third unit’s own indications in the check rather than inferring its state from two working PFDs.
Check. The required inertial references are usable and no unresolved alignment/fault indication remains. [65, PDF pp. 3-5] [66, PDF pp. 486-491]
5. Finish the check before movement
Action. Return to this check before taxi if you continued other cockpit work during alignment. Confirm completion and the intended navigation source before relying on the programmed route.
Check. Preparation has gained time without moving the aircraft before the required alignment is complete. [66, PDF pp. 106-107] [23, PDF pp. 1010-1033]
Complete when: All required units have completed their alignment, the position reference is credible, and the flight displays provide usable attitude/heading information.