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FMS Temp Compensation

For VNAV approaches, VNAV temperature compensation helps the FMS meet obstacle clearance by adjusting waypoint altitude constraints for the approach, transitions, and missed approach for non-standard temperatures.

  • OFF — assumes standard-day temperature

  • COLD — compensation only in cold conditions (0 to −50 °DISA)

  • HOT&COLD — compensation in any temperature (−50 to +70 °DISA); must be enabled separately from COLD

Select temp config

COLD is the default. To change the mode:

  1. NAV INDEX 2/2 → MAINTENANCE

  2. FMS MAINTENANCE 2/2 → SETUP

  3. FMS SETUP → FLT CONFIG

  4. FLIGHT CONFIG 2/2 → TEMP COMP CONFIG — OFF / COLD / HOT&COLD

Add temp correction

The FMS computes compensated altitudes after destination OAT is entered on the LANDING page and an arrival is in the active plan. Pilot confirmation via the MOD flight plan is required before constraints update on active waypoints.

TEMP COMP is reached from LANDING INIT or from F-PLN when:

  • TEMP COMP CONFIG is COLD or HOT&COLD

  • Within 30 NM of destination

  • An approach is activated

  • Valid OAT on the LANDING page

Example workflow:

  1. PERF INDEX → LANDING INIT

  2. Enter LDG TEMP for the destination

  3. TEMP COMP (RSK 5)

  4. Verify altitudes → APPLY (RSK 6)

  5. MOD FLT PLAN → ACTIVATE (RSK 6)

See also PERF and NAV.

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