April 22, 2021

Limitations of the See and Avoid Principle 


Information provided by COPA

With flight training airspace becoming busier and general aviation activities have returned to a high level recently despite the COVID-19 pandemic, VFR traffic separation under the See and Avoid Principle has highlighted itself as an area for review and focus.

Over the last several years, the Transportation Safety Board has published many reports on VFR collisions where the limitations of the See and Avoid Principle have been highlighted.

As a quick review, the TSB has included the following wording found in Safety Investigation A20O0053: “When operating in accordance with VFR, or in accordance with IFR but in VMC [visual meteorological conditions], pilots have sole responsibility for seeing and avoiding other aircraft. Aural and visual alertness are required to enhance safety of flight in the vicinity of uncontrolled aerodromes.

“The see-and-avoid principle is the basic method of collision avoidance for VFR flights that is based on active scanning, and the ability to detect conflicting aircraft and take appropriate measures to avoid them.”

Additionally, the FAA has published the following on this subject: Pilots’ Role in Collision Avoidance  AC 90-48D CHG 1 (faa.gov)

While the documents and information above speaks to the limitations of the See and Avoid principle and recommends the use of Collision Avoidance System equipment, one small item that all VFR pilots can do to increase their aircraft visibility is very simple: TURN ON THE LANDING LIGHT.

Catching the glint of a landing light coming in the opposite or crossing direction may just give you that extra second needed to avoid a collision. The Transport Canada Aeronautical Information Manual also speaks to the issue both in the RAC and AIM sections of the manual.  It is a simple an effective manner to increase aircraft visibility both day and night and in weather conditions that only just meet VFR requirements.

RAC 4.1 General and AIR 4.5 Collision Avoidance both speak to the effectiveness of using the landing lights for enhanced visibility and conspicuity. Several operators have, for some time, been using their landing lights when flying at lower altitudes and within terminal areas, both during daylight hours and at night. Pilots have confirmed the use of landing lights greatly increases the probability of the aircraft being seen. An important side benefit is that birds appear to see aircraft showing lights in time to take avoiding action. In view of this, it is recommended that, when so equipped, all aircraft use landing lights during the takeoff and landing phases and when flying below 2 000 ft AGL. All Canadian cars today use daytime running lights to assist in spotting traffic on the roads and highways. Aviation should be doing the same thing now that LED landing lights are common place and energy efficient.

(Photo: Maksym Dragunov, AdobeStock)