Avoiding Mid Air Collisions (MACs): 5 Seconds to Impact

The UK Airprox Board (UKAB) has released a video with tips for pilots on preventing mid air collisions.

5s mac

The Airprox Board explain that:

Every year there’s an increase in Airprox as spring and summer arrives. On average, statistics show one mid-air collision occurs for every 60 Airprox incidents in UK airspace.

An Airprox 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.

five seconds to impact avoiding mid-air collisions UK airprox board

So much can happen in a matter of seconds:

Research shows that in normal circumstances the average pilot needs anything from nine to 12.5 seconds from spotting another aircraft to processing the closure geometry and manoeuvring to avoid a potential collision in a controlled manner. You may only have 5 seconds or so between the eye detecting an aircraft head-on and impact.

MAC Prevention: 6 Themes

There are six themes from previous incidents that the Board say: “can help cut the risks if pilots apply them every time they fly” (click on the image for more details):

six themes avoiding mid-air collisions UK airprox board

The UK Airprox Board

The role of the UK Airprox Board is to assess reported Airprox to enhance air safety.

To emphasise both the scope of its work and its independence, UKAB is sponsored jointly, and funded equally, by the UK Civil Aviation Authority (CAA) and the UK Military Aviation Authority (MAA).

Other MAC Safety Resources

The UK CAA provides further guidance in Safety Sense Leaflet 13 – Collision Avoidance.

The US National Transportation Safety Board (NTSBhave issued a Safety Alert on MACs: Prevent Midair Collisions: Don’t Depend on Vision Alone

Aerossurance has previously published:

Back in 1991 the then Bureau of Air Safety Investigation (BASI), now the Australian Transport Safety Bureau (ATSB) published:  Limitations of the See-and-Avoid Principle

The European Aviation Safety Agency (EASA) has published this research report: EASA.2011.07 Scoping improvements to ‘see and avoid’ for General Aviation

UPDATE 2 July 2017: North Sea S-92A Helicopter Airprox Feb 2017

UPDATE 30 August 2017: NTSB: Do We See and Avoid or Avoid Seeing?

UPDATE 24 November 2018: AAIB Highlight Electronic Conspicuity and the Limitations of See and Avoid after MAC (Cessna 152 G-WACG and Guimbal Cabri G2 G-JAMM)

UPDATE 30 December 2018: Fatal Biplane/Helicopter Mid Air Collision in Spain, 30 December 2017

UPDATE 25 January 2019: Airbus Helicopters AS350B3 I-EDIC engaged in heli-skiing and Jodel D.140E Mousquetaire IV F-PMGV collided in mid air over the Rutor Glacier in Italy.  Eight of the nine persons on board the two aircraft died.

UPDATE 2 February 2019: A319 / Cougar Airprox at MRS: ATC Busy, Failed Transponder and Helicopter Filtered From Radar

UPDATE 16 February 2019: Merlin Night Airprox: Systemic Issues

UPDATE 18 March 2019: UK CAA has  launched a call for evidence on proposals for the wider roll-out of Electronic Conspicuity in the UK (CAP1776).

UPDATE 19 April 2019: Enabling ADS-B OUT for General Aviation gathers pace says NATS

NATS, the CAA and EUROCONTROL worked with EASA to draft standard modification CS‑SC005a, and a significant number of aircraft owners with ADS-B capable transponders can now take advantage of it, with the view that the more aircraft that are electronically conspicuous to other airspace users, the safer it is for everyone in the air.

Details of standard modification CS-SC005a can be found on the EASA website.

The Simultaneous Surveillance report can be downloaded here.

UPDATE 12 May 2019: Alaskan Mid Air Collision at Non-Tower Controlled Airfield

UPDATE 5 August 2019: In response to the Cessna 152 G-WACG and Guimbal Cabri G2 G-JAMM accident the Buckinghamshire coroner has issued a recommendation to UK CAA on electronic conspicuity.

UPDATE 15 August 2019: UK CAA issue their response to the CAP 1776 Electronic Conspicuity consultation (CAP1873). The document includes views gathered at the Share the Air Conference in June 2019.

UPDATE 16 December 2019: Airprox Board article on electronic conspicuity.

UPDATE 14 August 2021: Alpine MAC ANSV Report: Ascending AS350B3 and Descending Jodel D.140E Collided Over Glacier

UPDATE 18 June 2022: Limitations of See and Avoid: Four Die in HEMS Helicopter / PA-28 Mid Air Collision

Some other past MAC accident reports include:

Avoiding mid-air collisions UK airprox board

Aerossurance has extensive air safety, operations, airworthiness, human factors, aviation regulation and safety analysis experience.  For practical aviation advice you can trust, contact us at: enquiries@aerossurance.com