Procedures for Air Navigation Services

Understanding ICAO Procedures for Air Navigation Services (PANS)

Procedures for Air Navigation Services (PANS) are globally harmonized ICAO provisions that standardize how air traffic is managed and how instrument procedures are designed and flown. For ATPL students, two core documents matter most: PANS-OPS (Doc 8168) for instrument flight procedures and obstacle clearance, and PANS-ATM (Doc 4444) for air traffic management, separation minima, and phraseology. These aviation regulations underpin routine operations such as holding entries, instrument approaches, missed approaches, and the application of wake turbulence and radar separation. They also clarify how altitude/flight levels are expressed near aerodromes and define ATS airspace classifications and their associated VFR/IFR rules.

On the procedures side, PANS-OPS sets the framework for instrument approaches and obstacle protection. For example, a nominal missed approach climb gradient of 2.5% is assumed unless a higher value is published. In the intermediate approach segment, the minimum obstacle clearance reduces to 150 m (492 ft) by the end of the primary area. Typical ILS glide path interception occurs between about 300 m (984 ft) and 900 m (2,955 ft)MDA on a circling approach requires that the required visual references are established and maintained; if visual contact is lost while circling, initiate a go-around with an initial climbing turn toward the runway to regain situational awareness and then fly the published missed approach. For holding or reversal procedures, entry selection is based on inbound track and protected sectors; depending on geometry and technique, parallel or offset (teardrop) entries can both be appropriate. States prescribe Required Navigation Performance (RNP) specifications on the basis of regional air navigation agreements, aligning equipage and route design regionally.

PANS-ATM governs separation minima and aerodrome control practices. While the standard radar separation is 5 NM, it may be reduced to, but not less than, 3 NM where facilities permit. Wake turbulence rules require a 2‑minute interval for a medium departing behind a heavy from the same runway. When aircraft pass through each other’s level on the same track, apply at least 15 minutes longitudinal separation at the crossing time. At the commencement of final approach, controllers pass significant wind component changes; a noteworthy example is a 2 kt tailwind change. With an arriving aircraft on a straight‑in instrument approach, departures may be restricted—no takeoff within 5 minutes before the arrival is estimated over the instrument runway. Regarding ATS airspace, Class B provides ATC separation for all flights (IFR and VFR). In Class D, IFR are separated from IFR and all flights receive traffic information. Class C VFR minima at or above 3,050 m (10,000 ft) AMSL are 8 km visibility and 1,500 m horizontal/300 m vertical from cloud. A Control Zone (CTR) extends from the surface upward, whereas a Control Area (CTA) extends upward from a specified limit—its lower limit is not less than 200 m (660 ft) AGL. Below FL290, the vertical separation minimum for IFR is 1,000 ft (300 m). In the vicinity of the aerodrome, vertical position is expressed as altitude (AMSL) at or below the transition altitude; above, flight levels are used.

What this question bank covers

• PANS-OPS instrument procedures: holds/entries, ILS intercept, MDA/Circling, missed approach gradients and execution.
• PANS-ATM separation standards: radar minima (5 NM/3 NM), longitudinal crossing, wake turbulence intervals, wind reporting.
• ATS airspace classifications (B, C, D), VFR/IFR rules, and visibility/cloud clearance requirements.
• CTR vs CTA structure, lower limits, transition altitude concepts, altitude vs flight level usage.
• Navigation specifications and RNP policy set by States via regional air navigation agreements.

Mastering these Procedures for Air Navigation Services builds the legal and technical foundation for safe operations and exam success in ATPL theory, tying aircraft performance and systems with standardized air traffic services and instrument procedure design.