Descent checklist item

[youngie63 4]

G'day All

This more out of curiosity than anything else. In the SOP2 (P3D) descent checklist there is an item call "Map Integrity". Can someone please shed some light on what this is. I spoke to a mate who is a 744 Capt with Qantas and he had no idea what it is as it is not part of any of their checklists.

cheers

[byork 2,259]

MAP Display Integrity Check The MAP display should be checked for integrity (MAP position shift error) by one or more of the following methods:

En-Route (Radio navaids not available or WPT crossing on IRS only navigation legs.)

- Select map on ND mode selector with range 10.

- Select POS map switch and observe IRU position stars relative to FMC position. If any IRU position in excess of 5 nm difference from FMC position, determine most accurate IRU for use in event of future navigation system malfunction by use of CDU position of NAV source selector switch.

Approach

- The map display is considered an additional aid to approach. Radio navaid raw data is always the primary approach aid. Map integrity should be verified before the approach is commenced.

- With one or more VOR stations tuned, select POS map switch.

- Observe raw data VOR radial (and DME range tick if appropriate) passes through FMC generated VOR station symbol.

- If the above method does not produce a satisfactory check, enter the VOR(s) in use as fixes on the fix page(s).

- Compare FMC generated bearing/distance with raw data radial/DME. If the map position error can be verified to 1 nm or less use of the navigation displays is as follows:

Precision Approach:

PF- MAP

PNF- MAP

Non-Precision Approach:

See Normal Procedures If verification is not possible, or the required accuracy cannot be achieved, the MAP display must be treated with caution and is restricted to the PNF display for monitoring purposes. In this case, the PF must display APP or VOR for all approaches. Note that an unacceptable check following a lengthy leg without DME updating may well become acceptable by the time of commencement of the approach after a period of radio updating - thus repeat map integrity check at an appropriate time prior to commencing approach.
 

[youngie63 4]

Thank Bryon, very comprehensive. As stated couldn't find anything in the FS2crew doco, on Google or in the Qantas manuals.

cheers