Recurring concern

Inadequate visual collision-avoidance controls for aircraft in flight

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First reported 12 Jan 2018•Latest report 24 Jul 2023

Definition

What this concern includes

Includes failures of controls specifically dedicated to preventing aircraft collisions through visual detection, visual assessment, compatible warning or anti-collision systems, and consideration or mitigation of background visual interference and relevant weather or lighting conditions.

Not included

Excludes generic aviation training, air-traffic-control, airfield-management or communication deficiencies unless they directly concern visual collision avoidance between aircraft.
Excludes road, marine, pedestrian or ground-vehicle visibility hazards.
Excludes aircraft equipment or maintenance failures unrelated to detecting, distinguishing or warning of nearby aircraft.
Excludes the occurrence of an aircraft collision where no deficiency in a dedicated visual collision-avoidance control is identified.

Reports: 3
Individual concerns: 5
Date range: 2018–2023
Stated actions: 10

Reports over time

Reports about this concern issued each year.

* 2026 is projected from reports observed to 7 Sep 2026.

Most frequent recipients

Reports about this concern sent to each recipient.

Civil Aviation Authority2

Heathrow Airport Limited1

Concerns and responses across reports

Only concerns grouped under this recurring concern are included. Select any concern, action or position to view the source wording.

24 Jul2023
West London
Concerns raised1
1. Lack of specific consideration of background visual interference
This report raised 1 other concern. They are not shown here because they do not form part of this recurring concern.
Responses linked to these concerns
Each statement is shown once, even when linked to more than one concern.
Actions described in response 1
1. Action
  Commission and complete an expert assessment of airside visual interference and vehicle-identification mitigations.
  Stated by Heathrow Airport LimitedStated completed
Respondent positions 2
1. Position
  Background visual interference at Heathrow does not create greater distraction for airside drivers than comparable normal street scenes.
  Stated by Heathrow Airport LimitedDisputes the concern
1. Position
  No realistic or practicable intervention can influence background visual interference because little or no change can be made to the visual environment.
  Stated by Heathrow Airport LimitedUnable to act
AI-generated summary

John David Coles · Prevention of Future Deaths report

This summary was generated using AI from the published report. Please read the original report for the complete account.

Report summary

John David Coles died after a Heathrow Airport Ltd HiLux vehicle struck the British Airways Renault Kangoo he was driving while crossing an uncontrolled taxiway crossing at Heathrow Terminal 5. The concerns included background visual interference affecting the HiLux driver's ability to see the Kangoo and the difficulty of seeing white-coloured vans, including possible consideration of side profile lights for vehicles crossing uncontrolled crossings.

Read the report on judiciary.uk
Source evidence
How this individual concern was interpreted
PFD Monitor created a concise, searchable interpretation from the report wording shown below.
PFD Monitor interpretation
Lack of specific consideration of background visual interference
Wider context from the report
“(1) This fatal accident occurred well over 5 years ago. The expert report of ████████, ████████ which raised the issue of background visual interference as a possible causative factor, was produced well over 4 years ago. Nonetheless, prior to the inquest, no specific consideration appears to have been given to this phenomenon by HAL (or by the HSE or in the Jacobs report which HAL commissioned). (2) Indeed, in evidence, you seemed reluctant to accept that this might have been a factor (and may therefore be a factor in a future accident). Despite your Counsel’s submissions, therefore, I believe it is necessary to highlight this hazard by way of this report and to obtain your (HAL’s) response. ”
Source location
John David Coles · Prevention of Future Deaths report
Page 1 · concerns
Open source report
Source evidence

How this respondent action was interpreted

PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

PFD Monitor interpretation
Commission and complete an expert assessment of airside visual interference and vehicle-identification mitigations.

Verbatim wording from the response
“For that reason, the first action taken was to commission recognised experts to consider the above matters of concern and to make recommendations. HAL commissioned Transport Research Laboratory ("TRL") to carry out an assessment of the airside environment.”

Source location
Response from Heathrow
Page 2 · response
Published 4 August 2023
Open published response
Source evidence

How this respondent position was interpreted

PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

PFD Monitor interpretation
Background visual interference at Heathrow does not create greater distraction for airside drivers than comparable normal street scenes.

Verbatim wording from the response
“TRL's research concluded that there is background visual interference when driving airside at Heathrow, making particular note of the lighting in and around the terminals. However, TRL concluded that the lighting in and around the terminals did not create a greater visual distraction than normal street lighting would do for persons driving outside the airport environment.”

Source location
Response from Heathrow
Page 2 · response
Published 4 August 2023
Open published response
Source evidence

How this respondent position was interpreted

PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

PFD Monitor interpretation
No realistic or practicable intervention can influence background visual interference because little or no change can be made to the visual environment.

Verbatim wording from the response
“TRL concluded that there is not a realistic or practicable intervention that could be introduced to influence the background visual interference. This conclusion was reached as, in practical terms, little or no change can be made to the visual vista.”

Source location
Response from Heathrow
Page 2 · response
Published 4 August 2023
Open published response
17 May2019
Buckinghamshire
Concerns raised2
1. Reliance on “See and Avoid” procedures that cannot reliably detect craft concealed by blind spots
2. Lack of universal carriage of inter-craft electronic proximity warning or collision avoidance devices
This report raised 2 other concerns. They are not shown here because they do not form part of this recurring concern.
Responses linked to these concerns
Each statement is shown once, even when linked to more than one concern.
Actions described in response 6
1. Action
  Continue investing resources in developing electronic conspicuity devices to mitigate mid-air collision risk in uncontrolled airspace.
  Stated by Civil Aviation AuthorityStated in progress
2. Action
  Ensure pilots understand the limitations of see-and-avoid techniques through training and safety guidance.
  Stated by Civil Aviation AuthorityStated completed
3. Action
  Review airprox reports and analyse UK Airprox Board findings to identify causal factors, lessons and potential safety action.
  Stated by Civil Aviation AuthorityStated completed
1. Action
  Manage mid-air collision data and use evidence to steer mitigation strategies collaboratively with industry.
  Stated by Civil Aviation AuthorityStated in progress
2. Action
  Encourage development and deployment of interoperable, practical and affordable electronic conspicuity devices.
  Stated by Civil Aviation AuthorityStated in progress
3. Action
  Contribute to updating and improving accessibility of the Skyway Code as guidance on airmanship and collision prevention.
  Stated by Civil Aviation AuthorityStated in progress
AI-generated summary

Jaspal Singh BAHRA and 3 others · Prevention of Future Deaths report

This summary was generated using AI from the published report. Please read the original report for the complete account.

Report summary

Jaspal Singh Bahra, Saavan Singh Mundae, Michael Leonard Green and Thanh Trung Nguyen died at the scene after the aircraft they were flying collided over Wilderness Wood in Buckinghamshire on 17 November 2017. The report raised concerns about reliance on the “See and Avoid” procedure in unregulated airspace without universal electronic proximity warning or collision-avoidance devices, and about the lack of mandatory carbon monoxide monitors or warning devices in light aircraft.

Read the report on judiciary.uk
Source evidence
How this individual concern was interpreted
PFD Monitor created a concise, searchable interpretation from the report wording shown below.
PFD Monitor interpretation
Reliance on “See and Avoid” procedures that cannot reliably detect craft concealed by blind spots
Wider context from the report
“(1) It was clear from the evidence of The Air Accidents Investigation Branch (AAIB) and The Civil Aviation Authority (CAA) that aircraft such as the two involved in this collision operate in unregulated Class G airspace such as exists in the area of this collision without the requirement to carry any inter-craft electronic proximity warning or collision avoidance devices and are primarily kept safe by operating under the “See and Avoid” procedure which remains the same today as it was on 17th November 2017 (when the collision occurred). It appears this has also been the case for many years before that. This procedure is entirely reliant upon pilots seeing other craft and undertaking periodic clearing turns to try to bring craft into view which might be concealed by a blind spot particular to that craft. It was the view of the AAIB that the “See and Avoid” procedure was central to the cause of this collision. Although evidence was given by CAA about movement towards the introduction of electronic devices, it was clear that, without universal application, small craft would remain at risk and that timescales for implementation are unclear, leaving “See and Avoid” as the continuing process by which these types of craft avoid collisions. ”
Source location
Jaspal Singh BAHRA and 3 others · Prevention of Future Deaths report
Page 1 · concerns
Open source report
Source evidence
How this individual concern was interpreted
PFD Monitor created a concise, searchable interpretation from the report wording shown below.
PFD Monitor interpretation
Lack of universal carriage of inter-craft electronic proximity warning or collision avoidance devices
Wider context from the report
“(1) It was clear from the evidence of The Air Accidents Investigation Branch (AAIB) and The Civil Aviation Authority (CAA) that aircraft such as the two involved in this collision operate in unregulated Class G airspace such as exists in the area of this collision without the requirement to carry any inter-craft electronic proximity warning or collision avoidance devices and are primarily kept safe by operating under the “See and Avoid” procedure which remains the same today as it was on 17th November 2017 (when the collision occurred). It appears this has also been the case for many years before that. This procedure is entirely reliant upon pilots seeing other craft and undertaking periodic clearing turns to try to bring craft into view which might be concealed by a blind spot particular to that craft. It was the view of the AAIB that the “See and Avoid” procedure was central to the cause of this collision. Although evidence was given by CAA about movement towards the introduction of electronic devices, it was clear that, without universal application, small craft would remain at risk and that timescales for implementation are unclear, leaving “See and Avoid” as the continuing process by which these types of craft avoid collisions. ”
Source location
Jaspal Singh BAHRA and 3 others · Prevention of Future Deaths report
Page 1 · concerns
Open source report
Source evidence

How this respondent action was interpreted

PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

PFD Monitor interpretation
Continue investing resources in developing electronic conspicuity devices to mitigate mid-air collision risk in uncontrolled airspace.

Verbatim wording from the response
“The CAA anticipates that the further development and deployment of universally-compatible electronic conspicuity devices will aid in mitigation the risk of future mid-air collisions occurring in Class G (uncontrolled) airspace. As such, this is an area in which the CAA has invested and will continue to invest significant resources.”

Source location
2019-0160-Response-by-Civil-Aviation-Authority
Page 1 · response
Published 2 August 2019
Open published response
Source evidence

How this respondent action was interpreted

PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

PFD Monitor interpretation
Ensure pilots understand the limitations of see-and-avoid techniques through training and safety guidance.

Verbatim wording from the response
“However, pending such further advancement and subsequent adoption, the CAA continues to address the associated risk by ensuring that pilots are cognisant of the limitations of ‘see and avoid’; reviewing reports of airprox incidents identifying causal or contributory factors; collaborating with industry stakeholders through the Mid-Air Collision Programme and recommending or acting where appropriate to mitigate the risk of such incidents occurring.”

Source location
2019-0160-Response-by-Civil-Aviation-Authority
Page 1 · response
Published 2 August 2019
Open published response
Source evidence

How this respondent action was interpreted

PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

PFD Monitor interpretation
Review airprox reports and analyse UK Airprox Board findings to identify causal factors, lessons and potential safety action.

Verbatim wording from the response
“However, pending such further advancement and subsequent adoption, the CAA continues to address the associated risk by ensuring that pilots are cognisant of the limitations of ‘see and avoid’; reviewing reports of airprox incidents identifying causal or contributory factors; collaborating with industry stakeholders through the Mid-Air Collision Programme and recommending or acting where appropriate to mitigate the risk of such incidents occurring.”

Source location
2019-0160-Response-by-Civil-Aviation-Authority
Page 1 · response
Published 2 August 2019
Open published response
Source evidence

How this respondent action was interpreted

PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

PFD Monitor interpretation
Manage mid-air collision data and use evidence to steer mitigation strategies collaboratively with industry.

Verbatim wording from the response
“Among other measures, the MAC Programme will continue to:”

Source location
2019-0160-Response-by-Civil-Aviation-Authority
Page 3 · response
Published 2 August 2019
Open published response
Source evidence

How this respondent action was interpreted

PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

PFD Monitor interpretation
Encourage development and deployment of interoperable, practical and affordable electronic conspicuity devices.

Verbatim wording from the response
“Among other measures, the MAC Programme will continue to:”

Source location
2019-0160-Response-by-Civil-Aviation-Authority
Page 3 · response
Published 2 August 2019
Open published response
Source evidence

How this respondent action was interpreted

PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

PFD Monitor interpretation
Contribute to updating and improving accessibility of the Skyway Code as guidance on airmanship and collision prevention.

Verbatim wording from the response
“The importance of maintaining an effective visual lookout is reinforced through CAA publications. In May 2019, the CAA published the second edition of the ‘Skyway Code’,² which is intended to provide pilots involved in non-commercial and flight training operations with practical guidance on the operational, safety and regulatory issues relevant to their flying. Its primary focus is safe aircraft operations and the safe use of airspace. It is oriented towards Visual Flight Rules (VFR) flight and provides guidance on the rules for the prevention of collisions; precautionary measures that pilots can take; techniques for effective visual scanning; the limitations of ‘see and avoid’ and available means of ensuring electronic visual conspicuity. The CAA intends that the Skyway Code will be reviewed annually to ensure it reflects the latest regulatory requirements and best aviation practice.”

Source location
2019-0160-Response-by-Civil-Aviation-Authority
Page 2 · response
Published 2 August 2019
Open published response
12 Jan2018
Leicester City and South Leicestershire
Concerns raised2
1. Limitations of visual collision avoidance in certain weather conditions
2. Lack of effective, compatible and mandatory aircraft collision-position and warning systems
This report raised 1 other concern. They are not shown here because they do not form part of this recurring concern.
Responses linked to these concerns
Each statement is shown once, even when linked to more than one concern.
Actions described in response 3
1. Action
  Publish CAP1391 specifications and requirements for electronic conspicuity devices.
  Stated by Civil Aviation AuthorityStated completed
2. Action
  Encourage licensing and carriage of compatible electronic conspicuity equipment to reduce mid-air conflicts.
  Stated by Civil Aviation AuthorityStated in progress
3. Action
  Drive the plan for operators to become electronically conspicuous through the MAC programme’s continuing collaborative safety improvements.
  Stated by Civil Aviation AuthorityStated in progress
Respondent positions 1
1. Position
  Strobe lighting is not a realistic conspicuity solution because glider weight and power-consumption constraints prevent its wider use.
  Stated by Civil Aviation AuthorityUnable to act
AI-generated summary

John Christopher Armstrong · Prevention of Future Deaths report

This summary was generated using AI from the published report. Please read the original report for the complete account.

Report summary

John Christopher Armstrong, a 70-year-old glider pilot, died on 4 December 2016 after his glider collided mid-air with a Cessna aircraft near Husbands Bosworth Airfield. The concerns included the limitations of visual “see and avoid” collision prevention, the lack of compatible or mandatory electronic conspicuity systems, and the absence of air traffic control at the airfield despite multiple aircraft being nearby.

Read the report on judiciary.uk
Source evidence
How this individual concern was interpreted
PFD Monitor created a concise, searchable interpretation from the report wording shown below.
PFD Monitor interpretation
Limitations of visual collision avoidance in certain weather conditions
Wider context from the report
“(1) A ‘see and avoid’ principle of avoiding collisions is subject to limitations of the human eye and may be a significant problem in certain weather conditions (as in this case, a low sun eye): 2) There is no effective way of one aircraft ascertaining another aircraft’s position in flight or have any warning of an impending collision. Some aircraft have alarms and/or anti-collision devices but (a) they are not necessarily compatible with other systems that are used and (b) they are not mandatory; (2) There was no Air Traffic control over Husbands Bosworth airfield even though there is a gliding club at the airfield and therefore, one would assume, a higher usage of airspace and likelihood of a collision. There were seven aircraft in the vicinity at the time of the accident (including the two aircraft involved in the accident) but no-one controlling the position of the aircraft. ”
Source location
John Christopher Armstrong · Prevention of Future Deaths report
Page 1 · concerns
Open source report
Source evidence
How this individual concern was interpreted
PFD Monitor created a concise, searchable interpretation from the report wording shown below.
PFD Monitor interpretation
Lack of effective, compatible and mandatory aircraft collision-position and warning systems
Wider context from the report
“(1) A ‘see and avoid’ principle of avoiding collisions is subject to limitations of the human eye and may be a significant problem in certain weather conditions (as in this case, a low sun eye): 2) There is no effective way of one aircraft ascertaining another aircraft’s position in flight or have any warning of an impending collision. Some aircraft have alarms and/or anti-collision devices but (a) they are not necessarily compatible with other systems that are used and (b) they are not mandatory; (2) There was no Air Traffic control over Husbands Bosworth airfield even though there is a gliding club at the airfield and therefore, one would assume, a higher usage of airspace and likelihood of a collision. There were seven aircraft in the vicinity at the time of the accident (including the two aircraft involved in the accident) but no-one controlling the position of the aircraft. ”
Source location
John Christopher Armstrong · Prevention of Future Deaths report
Page 2 · concerns
Open source report
Source evidence

How this respondent action was interpreted

PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

PFD Monitor interpretation
Publish CAP1391 specifications and requirements for electronic conspicuity devices.

Verbatim wording from the response
“7. You also mention in your letter that the CAA has published CAP1391. This document is the result of many years of work of the Electronic Conspicuity Working Group (ECWG), that has striven to overcome the challenges of the need for low power consumption, portability and affordability to encourage the wider use of electronic conspicuity devices. The CAA, alongside the ECWG, has provided specifications to industry for such devices and is actively encouraging the licensing and equipage of such equipment, to minimise the incidents of mid-air conflict. There are several trials currently being run in the UK airspace to examine the efficacy of this equipment.”

Source location
2018-0008-Response-by-CAA
Page 2 · response
Published 7 March 2018
Open published response
Source evidence

How this respondent action was interpreted

PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

PFD Monitor interpretation
Encourage licensing and carriage of compatible electronic conspicuity equipment to reduce mid-air conflicts.

Verbatim wording from the response
“7. You also mention in your letter that the CAA has published CAP1391. This document is the result of many years of work of the Electronic Conspicuity Working Group (ECWG), that has striven to overcome the challenges of the need for low power consumption, portability and affordability to encourage the wider use of electronic conspicuity devices. The CAA, alongside the ECWG, has provided specifications to industry for such devices and is actively encouraging the licensing and equipage of such equipment, to minimise the incidents of mid-air conflict. There are several trials currently being run in the UK airspace to examine the efficacy of this equipment.”

Source location
2018-0008-Response-by-CAA
Page 2 · response
Published 7 March 2018
Open published response
Source evidence

How this respondent action was interpreted

PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

PFD Monitor interpretation
Drive the plan for operators to become electronically conspicuous through the MAC programme’s continuing collaborative safety improvements.

Verbatim wording from the response
“12. The CAA will continue to drive forward the plan to ensure operators are ‘electronically conspicuous’ which will help to reduce the incidence of such events as those at Husbands Bosworth and others more recently. The risk of mid-air collision is a complex and long-term challenge and as such the CAA’s MAC programme aims to reduce the risk of mid-air collision by pursuing targeted and continuous improvements in systems, cultures, processes and capability. The MAC programme works closely and collaboratively with the UK Airprox Board, UK Flight Safety Committee, Military Aviation Authority and industry stakeholders to understand and assess risk and identify effective and collaborative mitigations. This programme also meets the European Plan for Aviation Safety (EPAS) requirement for Member States to address MAC in their safety plans.”

Source location
2018-0008-Response-by-CAA
Page 3 · response
Published 7 March 2018
Open published response
Source evidence

How this respondent position was interpreted

PFD Monitor created a concise, searchable interpretation from the published response wording shown below.

PFD Monitor interpretation
Strobe lighting is not a realistic conspicuity solution because glider weight and power-consumption constraints prevent its wider use.

Verbatim wording from the response
“use of stripes and bands of colour, but the key contributor to visual acuity is the use of strobe lighting and, due to weight and power consumption constraints, this has not proven to be a realistic solution. Some modern, high-end gliders are fitted with powerful batteries and in some cases even, a small engine to help sustain flight, but this is in a very small section of the gliding community.”

Source location
2018-0008-Response-by-CAA
Page 2 · response
Published 7 March 2018
Open published response

Data last updated 7 September 2026

What this concern includes

Not included

Reports over time

Concerns raised1

Lack of specific consideration of background visual interference

Actions described in response An action is something a respondent says it has done, is doing, or plans to do in response to the concern raised.1

Respondent positions A position is what a respondent says about the concern when they do not describe a specific action.2

Concerns raised2

Reliance on “See and Avoid” procedures that cannot reliably detect craft concealed by blind spots

Lack of universal carriage of inter-craft electronic proximity warning or collision avoidance devices

Actions described in response An action is something a respondent says it has done, is doing, or plans to do in response to the concern raised.6

Concerns raised2

Limitations of visual collision avoidance in certain weather conditions

Lack of effective, compatible and mandatory aircraft collision-position and warning systems

Actions described in response An action is something a respondent says it has done, is doing, or plans to do in response to the concern raised.3

Respondent positions A position is what a respondent says about the concern when they do not describe a specific action.1

Actions described in response 1

Respondent positions 2

Actions described in response 6

Actions described in response 3

Respondent positions 1