John Armstrong

Chief Executive's Office

HM Coroner
For Leicester City and South Leicestershire
The Town Hall
Town Hall Square
Leicester
LE1 9BG

23 February 2018

Civil Aviation
Authority

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Regulation 28 Report to Prevent Future Deaths —John Christopher Armstrong

refer to your letter dated 12 January 2018 regarding the mid-air collision between a
glider and a Cessna aircraft over Husbands Bosworth Airfield on 4 December 2016
which led to the regrettable death of Mr Armstrong.

2. 

In your letter, you highlight 3 areas of concern:

a.  The limitations of the see and avoid principle.
b.  The lack of an effective method to ascertain another aircraft's position in

flight.

c.  The lack of Air Traffic Control Provision over Husband's Bosworth airfield.

would like to address each of these issues in turn.

See and Avoid
3. 

In the absence of a full and comprehensive ground surveillance picture, where all
airborne are `electronically conspicuous' and subject to either monitoring or control by air
traffic services, the use of see and avoid has been an effective, if not infallible, method of
avoiding collision for many decades. But, as you quite rightly mention, it does have its
limitations.  Limitations of the `see and avoid' principle include: the difficulty of the human
eye in detecting other aircraft on a steady bearing (which would indicate a collision is
likely); blind spots within the aircraft (much as there is in a car behind the a-pillars);
visual conspicuity of small, often white objects against the sky (such as gliders); and as
in this tragic case, the position of the sun in the sky relative to each aircraft.  In addition,
whilst air traffic control is valid and effective within controlled airspace, the UK structure
enables large swathes of `open, uncontrolled' airspace where users are entitled to
operate with little or no electronic equipment or air traffic assistance.

4. 

The Mid-Air Collision (MAC) Working Group, chaired by the CAA and including
representation from across the flying spectrum, has examined the issue of visual
conspicuity over many years. There are things than can be done to improve conspicuity,
including different paint schemes and high intensity strobe lighting.  Gliders though are
painted predominantly white due to issues surrounding heat absorption and structural
integrity; patently against the majority of meteorological background conditions, this is far
from ideal. Some work has been done to raise the visual profile of gliders, including the

Civil Aviation Authority
K5, CAA House, 45-59 Kingsway, London, WC2B 6TE www.caa.co.uk
Telephone 020 7453 6003

 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.

Effective Method to Ascertain another Aircraft's position.
5. 

There are other facilities and items of equipment that can provide cues for `see and
avoid'; these include: making radio calls when passing an aerodrome, participation in an
Air Traffic Control (ATC) service, (an action which is not mandatory in the type of
airspace within which this event occurred), and the carriage and use of Electronic
Conspicuity equipment. The position of other aircraft can be ascertained by those
aircraft carrying interoperable electronic signal emitting transponders and, in some
cases, conflicts can be resolved by using collision avoidance technology. This is an
enhancement of the `see and be seen' principle known as `see, be seen and avoid'.

6.  As highlighted in your report, glider GCLJK was fitted with a system known as FLARM, a

lightweight collision avoidance solution particularly popular amongst the gliding
community as it is light weight and with minimal power requirements. FLARM is also in
use by some pilots in the General Aviation (GA) community but it is by no means
ubiquitous; FLARM operates on a different frequency to more capable electronic
transponders as favoured by the majority of larger aircraft around the world. FLARM has
great utility in dense traffic situations such as would exist with groups of gliders soaring
around a thermal but is largely incompatible with the equipment in different types of
aircraft.  Any form of electronic conspicuity equipment relies on all those in the vicinity
carrying compatible systems. Had- Glider GCLJK been fitted with a newer version of this
equipment PowerFLARM hops://flarm.com/products/powerflarm/ Mr Armstrong might
have been able to pick up emissions from Cessna GCSFC if it were carrying and
operating such a system, and thereby been given indication as to the presence of this
aircraft.

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.

8. 

Indeed, some of this work has already born fruit with at least 4 different devices being
declared as meeting the CAP1391 requirements and available for purchase for a few
hundred pounds. http://www.caa.co.uk/General-aviation/Aircraft-ownership-and-
maintenance/Electronic-Conspicuity-devices/ There is an intention that there will be
gradual convergence of technology and greater compatibility between systems as
technology advances and greater gains are made in miniaturisation.

Air Traffic Control Provision
9. 

As is with the case of the fitment of electronic conspicuity, the participation in an air
traffic control service is also not mandatory in this type of airspace. The gliding
community generally reserve their radio transmissions for club communications and
deconfliction with other gliders, whereas GA aircraft on a navigation exercise would
normally speak with ATC or air to Ground stations along their route, although this is not
mandatory unless they are planning to penetrate an air traffic control zone.

Civil Aviation Authority
K5, CAA House, 45-59 Kingsway, London, WC2B 6TE www.caa,co.uk
Telephone 020 7453 6003

 10.  Large parts of the airspace in the south of the UK are facilitated by the provision of a

Lower Airspace Radar Service (CARS) mainly provided by military units. However,
coverage is sparse in some areas. This service is provided through the long standing
joint and integrated approach to airspace regulation in the UK, which corrals the
capabilities of both civil and military facilities to the benefit of all airspace users. The
service is however entirely voluntary: there is no requirement to provide nor utilise the
service. It is understood from the AAIB report that the Cessna GCSFC was in
communication with Leicester Airport, but that aerodrome does not have a radar facility.
The provision of radar facilities at an aerodrome is a decision for the operator of the
airfield, although it does have a role to play at busier airports where commercial air
transport operates and where the CAA may require the operator to provide radar service
provision as part of the airport's safety management system. This is not the situation in
the case of Leicester aerodrome due to the small scale of their operation and the
absence of public transport flights.

1 1.  Whilst an air traffic service is a good cue to assist `see and avoid', it does depend on the
capabilities of the service provider (are they equipped with radar?), the ability of the
radar to detect aircraft made from composite non-radar reflective materials, and that all
aircraft in the same area are receiving a service from the same provider (i.e. on the
same frequency). The nature of gliding operations is such that preference is given to
remaining on a `gliding frequency'. Accordingly, the CAA and the various working
groups looking at these issues over the years, have concluded that proactively enabling
the development and manufacture of lightweight, low cost electronic conspicuity devices
and encouraging wider carriage of compatible electronic conspicuity devices is the best
option to mitigate the risks of mid-air conflict and the prevention of collision. It should be
noted however, that in a busy visual air traffic circuit, the utility of electronic conspicuity
devices is reduced, as pilots do not have the time to look into the cockpit to track other
aircraft -they must be predominantly "heads out" as this is the safest way of operating
with other aircraft that are using the circuit at the same time. Pilot education in the
dangers associated with circuit operations is currently the most effective tool.

Conclusion
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.

Yours sincerely

Andrew Haines
CHIEF EXECUTIVE

Civil Aviation Authority
K5, CAA House, 45-59 Kingsway, London, WC2B 6TE www.caa.co.uk
Telephone 020 7453 6003

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