Approaches are the final and most safety-critical phase of a flight. They guide an aircraft from a given altitude down toward a runway in a safe and predictable way. This works whether the pilot can see the runway or is flying fully on instruments.

In today’s S.O.A.R article, we will explain the different classifications of approaches around the world and how they work.

Below are the main types of approaches used in aviation:

1. Precision Approaches

Precision approaches give both lateral (horizontal) and vertical (up-down) guidance. These approaches allow aircraft to land in low visibility and bad weather.

Instrument Landing System (ILS)

ILS is the most common precision approach in the world and is still widely used.

• Localizer (LOC): Provides lateral or horizontal guidance to keep the aircraft lined up with the runway
  
• Glide Slope (GS): Provides vertical or up-down guidance, usually around a 3 degree descent
  

Precision Approach Categories

These categories apply to ILS and also other precision systems like GLS and LPV.

• CAT I:
  Decision height not lower than 200 feet
  Runway visual range not less than 550 meters
  
• CAT II:
  Decision height lower than 200 feet but not lower than 100 feet
  Runway visual range not less than 300 meters
  
• CAT III:
  Decision height lower than 100 feet or no decision height
  Visibility depends on aircraft and airport equipment. Used for Autoland.
  

GLS (GBAS Landing System)

GLS is a newer type of precision approach that uses satellites.

• Uses GNSS signals corrected by a local GBAS ground station
  
• Gives very accurate lateral and vertical guidance
  
• Allows more flexible approach paths than ILS
  
• Slowly being added at modern international airports
  

LPV (Localizer Performance with Vertical Guidance)

• GNSS based approach that uses SBAS
  
• Vertical guidance is very stable and similar to ILS
  
• Minimums are often close to ILS CAT I
  

2. Approaches With Vertical Guidance

These approaches provide vertical guidance but do not always use traditional ground transmitters.

LNAV/VNAV

• Provides lateral and vertical guidance using GNSS
  
• Vertical path is created by aircraft systems
  
• Not as accurate as LPV but still supports stabilized descents
  
• Common at airports without ILS equipment

RNP AR (Authorization Required)

• Advanced GNSS approaches used in difficult terrain
  
• Requires special aircraft approval and pilot training
  
• Allows curved flight paths and very tight accuracy
  
• Used at places like Innsbruck and Queenstown

3. Non-Precision Approaches

Non-precision approaches only provide lateral guidance. The pilot controls the descent using published altitude steps.

VOR Approaches

• Use ground based radio beacons
  
• Very reliable but slowly being phased out
  
• Still found at smaller airports
  

LOC Approaches

• Use only the localizer part of an ILS
  
• Very accurate laterally but no glide slope
  
• Often used as a backup to full ILS
  

RNAV (GNSS) LNAV

• GNSS based lateral guidance only
  
• No required vertical path
  
• Very common at airports without vertical guidance
  

4. Visual and Circling Approaches

Visual approaches depend mostly on what the pilot can see outside.

Types of Visual Approaches

• Visual Approach:
  ATC clears the aircraft when the runway or traffic is in sight. The pilot then flies visually to land.
  
• Circling Approach:
  The pilot flies an instrument approach that may not line up with any runway. After reaching the airport area, the pilot maneuvers visually to land on any suitable runway. Some approaches are designed this way because terrain or obstacles make straight-in approaches impossible.
  
• Contact Approach (FAA only):
  The pilot stays clear of clouds and uses ground reference. This type is not used very often.
  

Visual and circling approaches require good weather and strong pilot awareness.

In conclusion, aircraft approaches are carefully designed to match different levels of visibility, terrain, and airport equipment, ensuring flights can end safely in almost any condition. From highly precise systems like ILS, GLS, and LPV to simpler non-precision and visual approaches, each type has a specific role in modern aviation. Understanding these classifications helps explain why some airports can operate in heavy fog while others rely on clear weather and pilot judgment. Together, these approach types form a flexible and layered system that prioritizes safety, efficiency, and accessibility across the global aviation network.