# In-Flight Re-Planning

> Procedures for changing the flight plan while airborne.

- **Subject:** 033 — Flight Planning Monitoring
- **Section:** 033-06 — Flight Monitoring and In-flight Re-planning
- **Topic code:** 033-06-02
- **Last reviewed:** 2026-04-01
- **Author:** Pablo Asensio Martínez
- **HTML version:** https://pilotsyllabus.com/en/flight-planning-monitoring/flight-monitoring-and-in-flight-re-planning/in-flight-replanning/

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## Reasons for Re-Planning
*   **Weather**: Deterioration at destination or alternate.
*   **Fuel Shortage**: Use of contingency fuel exceeding limits or unforecast headwinds.
*   **Technical Failure**: Loss of engine, pressurization, or navigation equipment.
*   **Passenger Medical**: Requirement to land at nearest suitable airport.

## The Re-Planning Process (1-in-60 Rule)
For navigation deviations:
*   **Track Error Angle (TE)**: $\frac{Distance Off}{Distance Flown} \times 60$.
*   **Correction Angle**: To return to track in same distance: $2 \times TE$.
*   To fly direct to destination: Use new track and distance.

## Fuel Re-Assessment
When re-planning to a new destination (diversion):
1.  **Current Position**: Treat as the new "Departure Point".
2.  **Fuel on Board**: Treat as the new "Take-off Fuel".
3.  **Calculation**: Calculate Trip Fuel from *Current Position* to *New Destination* + Reserves.
    *   Is Current Fuel > Trip to Alternate + Reserves?
    *   If YES: Proceed.
    *   If NO: Land at nearest suitable aerodrome immediately.

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