# Specialised Operations (SPO)

> RVSM, PBN, MNPS/HLA, and Low Visibility Operations.

- **Subject:** 070 — Operational Procedures
- **Section:** 071-04 — Specialised Operations
- **Topic code:** 071-04-01
- **Last reviewed:** 2026-04-01
- **Author:** Pablo Asensio Martínez
- **HTML version:** https://pilotsyllabus.com/en/operational-procedures/specialised-operations/specialized-operations/

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## RVSM (Reduced Vertical Separation Minima)
Reduces vertical separation from 2,000 ft to **1,000 ft** between **FL290 and FL410** (inclusive).
*   **Goal**: Increases airspace capacity.
*   **Equipment Required**:
    *   2 Independent Altimetry Systems.
    *   1 Automatic Altitude-keeping System (Autopilot).
    *   1 Altitude Alerting System.
    *   1 SSR Transponder with Altitude Reporting.
*   **Contingency**: If equipment fails, pilot must notify ATC ("Unable RVSM") and may be cleared out of RVSM airspace or given 2,000 ft separation.

## PBN (Performance Based Navigation)
Moved away from "Sensor Based" (VOR/NDB) to "Performance Based".
*   **RNAV (Area Navigation)**: Allows flight on any desired path using basic positioning (GNSS/DME-DME/IRS).
*   **RNP (Required Navigation Performance)**: RNAV + **On-board Performance Monitoring and Alerting**.
*   **Specification**: RNP 1 means the aircraft must be within 1 NM of the centerline 95% of the flight time.

## NAT HLA (North Atlantic High Level Airspace)
Formerly MNPS (Minimum Navigation Performance Specifications).
*   **Airspace**: FL285 to FL420 in the North Atlantic.
*   **Requirements**: Two Long Range Navigation Systems (LRNS). HF Radios (or SATCOM where authorized).

## LVO (Low Visibility Operations)

![ILS Approach](https://upload.wikimedia.org/wikipedia/commons/1/10/ILS_Approach_Runway_10.jpg)

*   **Take-off**: Low Visibility Take-off (LVTO) usually below 400m RVR.
*   **Approach Categories**:
    *   **CAT I**: DH >= 200ft, Vis >= 550m.
    *   **CAT II**: 100ft < DH < 200ft, RVR >= 300m.
    *   **CAT IIIA**: DH < 100ft (or no DH), RVR >= 175m.
    *   **CAT IIIB**: DH < 50ft (or no DH), 175m > RVR >= 50m.
    *   **CAT IIIC**: No DH, No RVR limits (Zero/Zero). Not currently approved anywhere (taxiing is the problem).

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Free study notes from pilotsyllabus.com. Not a substitute for training at an approved ATO.