Safety track record of Aviation demonstrates that it is the safest means of travel and also as an industry whose people are focused on continuous improvement. The prime safety goal of the air traffic management (ATM) of en route commercial flights is to reduce the risk of mid-air collisions.
According to ICAO Annex 11, the objectives of air traffic control (ATC) are to:
- Prevent collisions: Ensure that aircraft maintain a safe distance from each other and from obstructions
- Maintain an orderly flow: Ensure that air traffic moves smoothly and efficiently
- Provide information: Give pilots advice and information to help them fly safely and efficiently
- Coordinate search and rescue: Notify the appropriate organizations if an aircraft needs help and assist them if needed
ATC uses radar to monitor aircraft locations and radios to communicate with pilots. ATC issues clearances to ensure that aircraft are separated safely.
When the designated minima is not maintained, the incident or hazard is reported by a code word to designate aircraft proximity in an air traffic incident report called as “AIR PROX”.
Source: ICAO Doc 4444 PANS-ATM
What is “AIR PROX”
An AIR PROX is a situation in which, in the opinion of a pilot or air traffic services personnel, the distance between aircraft as well as their relative positions and speed have been such that the safety of the aircraft involved may have been compromised. (ICAO Doc 4444: PANS-ATM).
ICAO defines a series of classifications for AIR PROX events which have been reported and subsequently investigated by an appropriate body. It is required that this classification should be assigned on the basis only of actual risk, not potential risk. This means that only the residual risk after any avoiding action is considered. The available classification categories are:
- A – Risk of collision. The risk classification of an aircraft proximity in which serious risk of collision has existed. An A AIR PROX may or may not be deemed to be a Serious Incident as defined by ICAO Annex 13.
- B – Safety not assured. The risk classification of an aircraft proximity in which the safety of the aircraft may have been compromised.
- C – No risk of collision. The risk classification of an aircraft proximity in which no risk of collision has existed.
- D – Risk not determined. The risk classification of an aircraft proximity in which insufficient information was available to determine the risk involved, or inconclusive or conflicting evidence precluded such determination.
The definition and classification of an AIRPROX given above was agreed prior to the introduction of ground radar and airborne collision avoidance systems (ACAS) capable of measuring accurately the actual separation of the aircraft involved. So, do we need new definitions for AIR PROX, keeping in view the technology (ADS-B and ACAS), increased traffic in terms of Drones, Unmanned traffic and autonomous aircraft.
Reasons for AIR PROX
- Coordination of traffic when handing to other controller.
- Complex Procedure
- Mixed Operations could be – VFR and IFR traffic, Military and Civil traffic, UAV, Helicopter and Fixed wing traffic
- Non- compliance with established procedure
- Failure of equipment – Radars, Radio, ACAS, Transponder
- Ineffective Supervision of Trainee -Pilot or Controller
- Human Error
- Deliberate Violation of Procedures
Preventing AIR PROX
- Mandatory reporting and investigating AIR PROX.
- Reviewing Airspace Structure
- Recurrent Training of Pilots and Controllers
- Continuous Review of safety and risk
- Capacity building like radars, radio and surveillance infrastructure
- More PBN routes
- Planning SIDS and STARS for de-conflicting traffic
- SBAS to enhance accuracy
One clear message after 30 Jan 2025 Mid-air Collision in Washington DC is that it is not only the providers (ATC) and Operators (Airlines and Pilots) who must take responsibility for preventing accidents. The entire ATC system is based data processing and information flows based on CNS the communications, navigation and surveillance systems, The entire system operates under a regulatory regime. The Government sets up the regulatory regime. The safety regulator has to be confident that everything works safely not only on paper but also delivers the required safety standards. The regulator should take account of hazards to which they expose people.
“Paper doesn’t save people, people save people”
Be Safe. Happy Landings.
