CAP 658 – the law

CAP 658

Model Aircraft: A Guide to Safe Flying

Chapter 1 General Information

1 Introduction

The Civil Aviation Authority is empowered to regulate all civil flying activities over the

United Kingdom, including model aircraft.

The rules and regulations for flying are contained in the Air Navigation Order as a

series of Articles, established by parliamentary statute.

It is the legal responsibility of the operator of a model aircraft to ensure that the model

is flown safely. This publication is intended to provide guidance to anyone intending

to fly a model aircraft.

It is written in collaboration with the major UK aeromodelling associations who have

provided much of the operational detail.

Guidance is also given beyond the statutory requirements, so that the experience of

the aeromodelling associations can be of use to those new to flying model aircraft.

The publication is laid out as a series of general chapters, applicable to the flying of

any model, followed by more detailed information on flying particular types of aircraft,

such as helicopters or seaplanes.

Nothing in this publication is intended to conflict with the Air Navigation Order or other

legislation which, in case of doubt, must be considered as overriding.

A list of addresses of organisations referred to in this publication is given at Annex A.

This CAP, CAP 658, refers only to model aircraft used for sport and recreation.

Guidance on the use of Unmanned Aerial Vehicles (UAVs) for aerial work is contained

in CAP 722 Unmanned Aircraft System Operations in UK Airspace – Guidance.

Further advice on the operation of model aircraft and UAVs can be obtained from the

CAA’s Flight Operations Inspectorate (General Aviation) on +44 (0)1293 573540.

Some of the text of this publication is presented in the third person singular. For

conciseness, the pronoun ‘he’ is used throughout. ‘She’ should be substituted when


February 2012

Chapter 2 Legal Requirements

1 Definition of a Model Aircraft

1.1 For the purposes of this document a ‘model aircraft’ is defined as any ‘Small

Unmanned Aircraft (SUA)’ (0-20 kg) used for sporting and recreational purposes and

a ‘large model aircraft’ is defined as any ‘Unmanned Aircraft’ (over 20 kg) used for

sporting and recreational purposes. The Air Navigation Order (ANO) 2009 contains the

legal definition of ‘Small Unmanned Aircraft’ and this definition is listed in this chapter.

1.2 The ANO uses the term ‘small unmanned aircraft’ rather than ‘model aircraft’ so that

‘Unmanned Aerial Vehicles’ (UAVs) and other flying machines are captured. This

publication is specifically written to cover model aircraft used for sporting and

recreation purposes and therefore the terms ‘model aircraft’ or ‘large model aircraft’

are used throughout.

2 Legal Definition of a Small Unmanned Aircraft

Small Unmanned Aircraft (Article 255) – ‘Any unmanned aircraft, other than a balloon

or kite, having a mass of not more than 20 kg without its fuel but including any articles

or equipment installed in or attached to the aircraft at the commencement of its


NOTE: For electrically powered models the batteries must be included as part of the

20 kg limit. The batteries are in effect regarded as the fuel tank and electrons

are regarded as the fuel.

3 Aviation Regulation that Applies to Model Aircraft and Large Model


3.1 The ANO contains the regulations that apply to all aircraft including model aircraft and

large model aircraft. The regulations are contained in a number of articles. The ANO

can be obtained online at

3.2 Model aircraft are excluded from the vast majority of the regulations applied to other

aircraft. Large model aircraft are not excluded from any of these regulations and

therefore require an exemption to be issued prior to flying.

3.3 The legal requirement for safety is placed firmly on the operator of the model and the

guidelines in Chapter 5 show what are considered reasonable conditions for the

operation of models.

4 Model Aircraft Regulations

4.1 The regulations which DO apply to model aircraft are explained briefly in this Chapter

and are listed in Annex B.

4.2 However, the most important regulations – articles 138, 166 and 167 of the ANO

2009 – deserve fuller explanation.

4.2.1 Article 138 – Endangering safety of any person or property

‘A person must not recklessly or negligently cause or permit an aircraft to endanger

any person or property.’

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All model flying activity is controlled by this article of the ANO and it is important that

the operator of any model aircraft should bear this in mind at all times.

4.2.2 Article 166 – Small unmanned aircraft

‘(1) A person must not cause or permit any article or animal (whether or not attached

to a parachute) to be dropped from a small unmanned aircraft so as to endanger

persons or property.

(2) The person in charge of a small unmanned aircraft may only fly the aircraft if

reasonably satisfied that the flight can safely be made.

(3) The person in charge of a small unmanned aircraft must maintain direct, unaided

visual contact with the aircraft sufficient to monitor its flight path in relation to

other aircraft, persons, vehicles, vessels and structures for the purpose of

avoiding collisions.

(4) The person in charge of a small unmanned aircraft which has a mass of more than

7 kg excluding its fuel but including any articles or equipment installed in or

attached to the aircraft at the commencement of its flight, must not fly the


(a) in Class A, C, D or E airspace unless the permission of the appropriate air traffic

control unit has been obtained;

(b)within an aerodrome traffic zone during the notified hours of watch of the air

traffic control unit (if any) at that aerodrome unless the permission of any such

air traffic control unit has been obtained; or

(c) at a height of more than 400 feet above the surface unless it is flying in

airspace described in sub-paragraph (a) or (b) and in accordance with the

requirements for that airspace.

(5) The person in charge of a small unmanned aircraft must not fly the aircraft for the

purposes of aerial work except in accordance with a permission granted by the


4.2.3 Article 167 – Small unmanned surveillance aircraft

‘(1) The person in charge of a small unmanned surveillance aircraft must not fly the

aircraft in any of the circumstances described in paragraph (2) except in

accordance with a permission issued by the CAA.

(2) The circumstances referred to in paragraph (1) are:

(a) over or within 150 metres of any congested area;

(b) over or within 150 metres of an organised open-air assembly of more than

1,000 persons;

(c) within 50 metres of any vessel, vehicle or structure which is not under the

control of the person in charge of the aircraft; or

(d) subject to paragraphs (3) and (4), within 50 metres of any person.

(3) Subject to paragraph (4), during take-off or landing, a small unmanned surveillance

aircraft must not be flown within 30 metres of any person.

(4) Paragraphs (2)(d) and (3) do not apply to the person in charge of the small

unmanned surveillance aircraft or a person under the control of the person in

charge of the aircraft.

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(5) In this article ‘a small unmanned surveillance aircraft’ means a small unmanned

aircraft which is equipped to undertake any form of surveillance or data


NOTE: The provision of data solely for the use of monitoring the model is not

considered to be applicable to the meaning of ‘surveillance or data


5 Large Model Aircraft Regulations

5.1 All large model aircraft having a mass of more than 20 kg (mass of model and

equipment, but excluding fuel) require an exemption to fly. A large model aircraft

can only be operated under the terms of an Exemption issued by the CAA.

5.2 An EXEMPTION is used to allow an exception to the established law. Such an

exception is usually only made subject to various additional conditions to ensure

adequate safety.

5.3 Anyone planning to build a very large model should first read Chapter 3 and contact

one of the modelling associations or the CAA to see if the proposed model is likely to

be acceptable.

5.4 It is unlikely that an exemption will be issued without the condition that the model

must be flown within the ‘control’ of a recognised model association and at a suitable


5.5 The maximum mass for a model aircraft to be treated under the guidelines of

CAP 658 is 150 kg. Above this mass full airworthiness regulations may apply. Builders

contemplating the construction of a model having a mass of more than 150 kg should

contact the CAA prior to commencing construction.

6 Article 137 – Endangering Safety of an Aircraft

‘A person must not recklessly or negligently act in a manner likely to

endanger an aircraft, or any person in an aircraft.’

Article 137 refers to people in an aircraft endangering the aircraft or persons therein,

whereas Article 138 refers to persons outside aircraft endangering aircraft. Obviously

only Article 138 can apply to a model aircraft. However, technically Article 137 does

apply to models over 20 kg.

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Chapter 3 Large Models between 20 kg and 150 kg

Exemptions and Permissions

1 The Need for Exemption

Large model aircraft having a mass between 20 kg and 150 kg are subject to all of the

Rules or Articles of the Air Navigation Order.

As many of these Rules are practically impossible for the model operator to meet, the

modeller must request a specific written Exemption to allow the model to be flown.

Any such Exemption will only be issued by the CAA subject to additional operating

conditions and after it has been satisfied that the model is designed, built and test

flown to a satisfactory standard.

Any person or group contemplating building an aircraft that is likely to have a

mass of more than 20 kg but less than 150 kg should apply at an early stage to

one of the modelling associations for advice. (See Annex A.)

The Large Model Association (LMA) operates a model inspection scheme on behalf

of all UK Aeromodelling Associations.

2 Design and Build Advice and Inspection

The LMA will advise on the availability of a member in the builder’s area who will be

able to supervise and assist with the project.

The assisting member will be authorised to confirm satisfactory design and build

standards to the CAA.

The build inspection schedule will be as agreed between the CAA and the LMA.

Details of the schedule will be sent on request by the association contacted.

It is particularly important to build to such a schedule if the construction does not

readily allow access to all parts of the model for a final inspection – such as box

sections or composite airframes.

In the case of Almost Ready To Fly (ARTF) power models where the construction

does not allow easy access to the structure, a manufacturer’s specification sheet

detailing the maximum engine capacity must be provided (where available) to the

LMA inspector.

In certain circumstances a charge may be made for elements of the above inspection


3 Exemptions

3.1 Flight Test Only

Once the inspection schedule has been satisfactorily completed, it will be forwarded

to the LMA who will issue a Certificate of Design and Construction. This certificate

should be forwarded to the CAA with a request for the issue of an Exemption – Test


Any special operating conditions applicable to the model can also be advised by the

LMA at this stage.

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The Exemption – Test Only is valid for one year and will only permit flights in private

(away from the public). During this time a Flight Test Log is to be completed. Details

and guidance notes about the completion of the Flight Test Log are available from the


The Exemption – Test Only will not normally be renewed after its expiration.

On satisfactory completion, the Flight Test Log should be returned to the LMA who

will then recommend the issue of an Exemption.

An Exemption is specific to a model and named pilot. No other person can legally fly

the model.

3.2 Flight Exemption

Once the Flight Test Schedule has been satisfactorily completed and a Flight Test Log

submitted, the LMA will make a recommendation to the CAA for the issue of an

Exemption. Any such Exemption issued will include any special operating conditions.

The Exemption is valid for one year and can be renewed by application to the CAA

with a statement that no changes have been made to the model.

If any changes have been made to the model it will have to be re-inspected and a new

Exemption – Test Only issued.

The CAA does not charge for the issue of Exemptions.

3.3 Gliders Having a Mass Between 20 kg and 80 kg

Pure gliders having a mass between 20 kg and 80 kg do now need an Exemption from

the CAA before they may be flown. Therefore, before a model glider between these

masses is built the advice of either the LMA or the British Model Flying Association

(BMFA) should be sought on construction, testing and operating techniques.

3.4 Gliders Having a Mass Over 80 kg

Pure gliders having a mass over 80 kg require an approval from the European Aviation

Safety Agency (EASA) (refer to Annex II to Regulation (EC) No. 216/2008).

4 Large Models Over 150 kg

Before commencing construction, the Airworthiness Division of the CAA should be

contacted to ascertain requirements (see Chapter 2, paragraph 5.5, and Annex A for

contact details). An approval from EASA may also be required.

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Chapter 4 Learning to Fly

1 Local Model Flying Clubs

If it is at all possible, contact and join a local model flying club – there is no doubt that

this is the best way to learn to fly.

There are many hundreds of model flying clubs in the UK and most of them offer

training in radio control flying to beginners in the sport.

Details of your local clubs can be obtained from the Associations listed in Annex A,

or you could enquire at your local model shop.

2 Learning to Fly Without a Model Flying Club

It is not impossible to learn to fly without being a member of a club, but it can be very


If you are unable to join a club to learn to fly, then try to get help from an experienced

model flyer who will be able to guide you in your first efforts.

Chapter 6 gives basic advice on radio controlled model flying.

3 Commercial Model Flying Training

There are a number of organisations and individuals offering commercial model flying


Details of these operations are listed in specialist model flying magazines or may be

obtained from local model shops.


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Chapter 5 Safety Considerations

1 Any Model Aircraft Flying


Choose an unobstructed site and at all times keep a safe distance from:


Only Fly

  • In suitable weather.
  • With regard for any other conditions such as local bye-laws.
  • With due consideration for other people and property.
  • With the model in direct unaided visual line of sight at all times.
  • If reasonably satisfied that the flight can be made safely.


Any powered model aircraft fitted with a receiver capable of operating in failsafe

mode should have the failsafe set, as a minimum, to reduce the engine(s) speed

to idle on loss or corruption of signal.

2 Additional Requirements – Models Having a Mass from 7 kg to 20 kg

Should only be flown

  • Clear of controlled airspace unless with Air Traffic Control (ATC) permission.
  • Clear of any Aerodrome Traffic Zone (ATZ) unless with ATC permission.
  • At less than 400 ft above the point of launch except with permission as above.
  • Well clear of any congested area of a city, town or settlement.
  • At least 50 m clear of persons, vessels, vehicles or structures. This can be reduced

to 30 m for take-off or landing. Other model operators and any assistants or

officials may be within this distance; as may vessels, vehicles or structures under

their control.


  • A serviceable ‘fail-safe’ mechanism should be incorporated to operate on loss

of signal or detection of an interfering signal. For example on an internal

combustion power driven model this should operate, as a minimum, to reduce the

engine(s) speed to idle.

  • Ensure that any load carried on the model is secure.

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3 Air Traffic Control and Controlled Airspace

Before flying within controlled airspace or an ATZ

  • Obtain permission from the appropriate air traffic control unit.

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Chapter 6 Flying Radio Controlled Models

1 General

Always fly with regard to the general regulations concerning radio control (R/C) flying

covered in Chapters 2 and 5.

Models should be checked thoroughly prior to each flying session and after any

abnormally hard landing.

Metal propellers must not be used on internal combustion engines or electric motors.

All R/C models are subject to in-flight vibration, landing knocks, transport damage etc.

Take care that receivers and batteries are well protected; servos are fixed securely;

control linkages (pushrods, snakes, closed loop etc.) are robust enough for their

purpose, are properly supported where necessary and are as slop free as possible and

that all control surface hinges and horns are fitted correctly.

It is recommended that you use welded or soldered re-chargeable battery packs in

your radio control equipment. Dry batteries may be adequate for use in transmitters

but their use in airborne battery packs is not recommended.

With new or repaired radio control equipment, a ground range check should be

performed, preferably with the equipment installed in a model. The ground range

check should be carried out in accordance with the manufacturer’s instructions,

taking care to look at the minimum distance (for the majority of 35 MHz transmitters

the minimum distance is around 50 metres with the transmitter aerial down). Make

sure that the model’s controls are still functioning correctly with no ‘jittering’.

It is also good practice to carry out a ground range check on your radio equipment at

regular intervals, at least every few months, and a check is advisable if the equipment

has not been used for a month or two.

When starting an engine, make sure that the model is restrained and cannot move


When preparing for a flight, check that transmitter trims, rate switches etc. are in their

correct positions and that each control surface on the model moves freely and in the

correct sense.

Immediately before take-off, flight controls should be checked again for full, free and

correct movement under full power if applicable. If there are any doubts as to their

operation, do not fly.

Before take-off, check that both ground and sky are clear and never take off or land

towards other pilots, spectators or the ‘pits’ area.

Maintain a clear view of the model and allow plenty of room between the flight path

and spectators, other flyers or model ‘pit’ areas. Avoid flying between yourself and

spectator or ‘pit’ areas, especially when landing.

Be aware of the sun’s position in relation to you and the model. Flying “through the

sun” can cause temporary blindness and the loss of control of the model. The use of

sunglasses is recommended – remember never look directly at the sun.

Avoid low overflight of houses, domestic gardens, car parks, traffic or spectators. You

have no control over people walking by at a reasonable distance from your

take-off/landing area but you should take care not to overfly them at low level.

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At any sign of malfunction or an unexpected loss of models parts, land as soon as it

is safe to do so.

When you decide to land, never assume that the landing area is clear. Always look

and be prepared to land in a safe place away from your planned landing area if

necessary. In all cases, the safety of people is paramount.

1.1 Pre Flying Session Checks

On arrival at the flying site, think S.W.E.E.T.S:

S Sun

W Wind

E Eventualities

E Emergencies

T Transmitter Control

S Site Rules

Sun Where is the sun in relation to where you will be flying? Will it

affect your flight patterns? What actions will you take if you

accidentally fly ‘through’ the sun? Should you be wearing

sunglasses? Remember that low sun in winter can be a particular


Wind Consider the wind strength and direction. How will this affect

your flights? Will you have to modify your normal take-off and,

especially, your landing patterns? From your local knowledge,

will there be any turbulence with ‘this’ wind direction and

strength? And how bad might it be?

Eventualities What will you do if you hear or see a full size aeroplane or

helicopter flying at low level near the field? What if the landing

area is suddenly obstructed when you are on finals to land? What

will you do if a nearby footpath or bridle path suddenly has

walkers or horses on it?

Emergencies You may have an engine cut at any part of a flight so consider

where your deadstick landings might be safely made and which

ground areas you should definitely avoid. How will you warn

other field users if you have an emergency?

Transmitter Control Is the site pegboard in operation? If not, why not? Where has the

pegboard been placed? Are you familiar with the system and do

you understand how it works?

Site Rules Are there any specific site rules you should be aware of? Most

importantly, where are the no-fly zones or dead airspace areas on

the site?


  • the airframe for any transit damage;
  • that servos and linkages are secure;
  • the undercarriage for secure fixing and correct alignment; and
  • the propeller for damage and secure fixing.

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1.2 Check before each Flight

  1. a) If frequency control is in operation, obtain clearance to transmit.
  2. b) Switch transmitter ON, confirm correct model is selected, then receiver ON.

Check that all controls operate freely and in the correct sense. Check that all

control surfaces are in their correct positions with the transmitter trims at neutral.

  1. c) Look for any minor radio malfunctions such as slow or ‘jittery’ servos, glitches, etc.

If in doubt, do not fly.

d i) With Internal Combustion (IC) models: after starting the engine and allowing it

to warm up, check that the pick-up from idle to full power is satisfactory. Hold

the model with its nose pointing upwards at a steep climbing angle for ten or

fifteen seconds and check engine operation at full power. If the engine falters

or cuts it is usually set to lean and must be re-tuned. Repeat the test until the

engine runs correctly in the nose-up attitude; or

  1. ii) With electric models:

1 The first and most important principle of electric flight ground safety is to

understand that the instant you start to plug in the flight battery, the model

you are holding may transform itself from a dead airframe into one with its

motor running at full revs and all controls moving. No matter how good your

other safety checks, you must be prepared for this to happen every single

time you start to connect the flight battery.

2 Since plugging in the flight battery is nearly always a two-handed job you

must give serious thought to how your model will be restrained BEFORE it

does something you don’t expect. When plugging in the flight battery,

positive restraint, either by a helper holding the model or by some other

method, and staying completely clear of the propeller must always be part of

your regular routine.

3 Electric motors have very different power and torque characteristics to

normal IC model engines. You must take very great care when setting up

their control systems and handling them as an accident, such as the propeller

hitting your hand, which would stall a glow engine, might just make an

electric motor turn even harder.

  1. e) Control Checks. Finally, with the aircraft held securely (usually on the ground for IC

models), open up to full power and re-check all flying controls again for full and free

movement, also noting any glitches, hesitations or odd vibrations. If ANYTHING

seems odd, DO NOT FLY.

  1. f) Double Check that all transmitter trims, rate switches, mixers etc. are in their

correct positions and that the transmitter meter is ‘in the green’.

1.3 Before Flying

Be S.M.A.R.T. with your transmitter

Switch on

Meter in the green / Model selection correct

Aerial secure and extended

Rate switches in all correct positions

Trims all in correct positions

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1.4 Checks after each Flight

  • Receiver OFF then transmitter OFF.
  • Clear the frequency control system if it is in operation.
  • Check propeller, airframe, undercarriage, wing fixing etc. for security of fastening

and for possible flight or landing damage.

  • Remember – avoid flying with a damaged aircraft or propeller, or with any possible

radio problem.

2 Radio Controlled Helicopters

Only fly with regard to the general regulations concerning radio control flying covered

in Chapters 2 and 5.

Take care to use sites which are of suitable size in relation to the type of manoeuvres

to be flown by the model.

Only fly after you have ensured that any spectators are well clear of the intended flight

path of the model.

Rotor blades should be carefully balanced before use.

For IC powered helicopters:

  • When starting the model in the pits, hold the rotor head firmly. When the engine

is running carry the model a sensible distance from other people before running up

or flying.

  • Do not release the rotor of the model until you are sure that it is safe to do so.
  • Never hold the model overhead to run up the engine or run the engine with no rotor

blades fitted.

For electric powered helicopters:

  • Electric helicopters should be carried out from the pits area with the flight battery

disconnected and it should only be connected in a safe area. The model MUST be

considered to be live as soon as this is done and great care is needed during this


2.1 A Model Helicopter Must Not be Flown or Run up:

  • In or near the ‘pits’ area or close to any spectators.
  • Directly towards the pits area or any spectators.
  • With metal rotor blades.
  • With knife-sharp leading edges on main or tail rotors.
  • With damaged or out of balance rotor blades. Note that blades, especially wooden

ones, should be reinforced at the root with hardwood, glass-fibre or some other

suitable material.

  • With radio equipment unproofed against shock and vibration.

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2.2 Checks Before a Flying Session

  • Check all ball links for slop and change as necessary.
  • Check that all rotor blades are in good condition with no damage apart from minor

tip damage.

  • Check for loose or missing nuts and bolts.
  • Check that there is no backlash in the drive system apart from gear backlash which

should not be excessive.

  • Check that servos are secure and free from contamination.
  • On IC models, check that the fuel tank and all piping is secure.
  • On electric models, check that the flight battery and associated wiring is secure.
  • Check that the receiver aerial is secure and in good condition with no chafing or


2.3 Checks before each Flight

  • If a helicopter suffers damage or a heavy landing, re-do all the pre-flying session


  • Check all controls before starting, especially for binding links or slowing of servos.
  • Check that the receiver aerial cannot become entangled with any moving or

rotating part.

  • Re-check controls at high rotor rpm just before lift-off. At the same time check

main rotor blades for true tracking (the rotor disk should be clear and steady). Any

excessive vibration should be eliminated before flight.

  • Double check that all switches on the transmitter are in their correct positions

before EVERY flight.

3 Gas Turbine Powered Models

The operation of gas turbine engines requires special care and the manufacturer’s

operating instructions must be understood and closely followed. All pilots and helpers

must be fully briefed on the operation of the engine before any starts are attempted.

Never run an engine in excess of the manufacturer’s recommended power rating.

Always follow the manufacturer’s recommendations on pipe work and fittings,

especially with regard to periodic renewal.

Take extra care during the engine’s initial operating period. Until the unit is proven, do

not operate it near people.

Pressurised gas fuels, such as propane, require care in handling; spill dispersal rates

can be slow and the gas can ‘pool’ in hollows or in void areas in fuselages. The liquid

can also cause frostbite, if allowed to come into contact with skin.

Ensure that all fuel is stored in labelled containers fit for the purpose. These

containers should be no larger than necessary.

All gas turbine models should be fitted with a failsafe. This must, as a minimum, bring

the engine to idle in the event of radio interference or failure. The fuel system must

be capable of manual shut-off via a fuel valve or fuel pump switch.

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3.1 Before Starting:

Smoking or naked flames must not be allowed near the engine and the fuelling area.

A suitable fire extinguisher (CO2, dry powder but not water) should always be present

at start-up and for any period during which the engine is running.

The start-up area should be kept clean and free from any loose items that may get

sucked into the fan or turbine.

Ideally the start-up area should be on a paved surface, but if this is not possible the

grass should be short and clear of all loose material.

Check the integrity of any compressed air hoses, clips etc., prior to turning on the air.

Manufacturers’ instructions should always be followed, particularly those relating to


Gas fuelled models must never be left in the pits area fuelled up. Once fuelled up they

should be moved directly to the designated start-up area.

3.2 Starting:

Gas turbines should normally be started facing into wind; however, ensure that the

jet tailpipe is never pointed at people or the pits area. The effect of the jet blast must

always be kept to the absolute minimum.

Beware of the possibility of “wet” starts with liquid fuels.

Whenever possible a reliable helper should assist with the start. The helper should be

close by and fully briefed on the operation of the engine. The helper should ensure

that you are not distracted during the start sequence.

Models must be physically restrained during start-up. The use of wheel brakes alone

is not sufficient.

3.3 Shutdown:

After every flight ensure that the engine is fully shut down, that the fuel shut-off has

been operated and that any hatches are opened to assist with engine cooling.

3.4 General Safety Information:

Adverse runway conditions can have an adverse effect on the aircraft’s performance

on take-off. e.g. wet or long grass will significantly increase take-off distance.

The rate of climb at take-off weight may be significantly less than that of a propeller

driven model aircraft. Care must be exercised to ensure safe clearance of any

obstacles immediately after take-off.

The lack of “prop wash” over the control surfaces of a jet propelled model aircraft will

result in less control surface effect, particularly at low speed.

4 Radio Controlled Silent Flight (Gliders and Electric Powered Models)

Flying radio-controlled gliders and electrically powered models (see also paragraph 5)

are essentially safe and environmentally acceptable pastimes provided a few basic

safety precautions are taken.

Passers-by and others who may be watching the flying, particularly at slope soaring

sites, tend to be unaware of the presence of gliders because gliders do not have

engines or propellers and so do not make a noise. The pilot must therefore exercise

even greater caution and awareness when flying on sites where the public are likely

to be present.

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If learning to fly, the best possible advice is to seek the help of members of your local

club. The shop where you bought the model or radio will usually help to put you in

contact with such a club. The BMFA and other specialist aeromodelling associations

will also be happy to advise.

(See Annex A for addresses.)

Before you even buy a model, local club members will be happy to advise on the best

type of model to build and fly. They can advise on finishing the model, installing the

radio and, most importantly, they can ‘trim’ the model for you so that it will fly safely.

For gliders with a mass in excess of 20 kg, see Chapter 3.

4.1 Launching the Glider

  • When using a towline, winch or bungee to fly from a flat field, always ensure

that no other model is endangered by checking above and behind before

releasing the model. Models landing always have priority over models launching.

  • Aerotowing the glider requires careful handling of both the tug and the glider.

Remember that to fly ANY model over 7 kg above 400 feet requires a permission.

Your local club may already have such a permission.

  • Ensure that any spectators are standing behind the launch point so that if the

model veers to either side, the spectators are not at risk.

  • When setting out the bungee, winch or towline, make sure that, when it

disengages from the model, it will not fall across powerlines, or adjacent roads or

pathways where passing vehicles or pedestrians could become entangled.

  • Check the proper operation of the radio and the movable surfaces of the

model before any launch. A previous hard landing may have caused some

unseen damage. Such a check will safeguard your model and will also minimise

the risk to bystanders, nearby property and vehicles.


4.2 Flying the Glider

  • When learning to fly, try to keep the model upwind and leave yourself with

plenty of altitude to make a proper landing approach.

  • Avoid flying the model directly into or across the sun; the glare may cause you

to lose sight of the model and effective control may be lost. Good sunglasses can

minimise this problem and also protect your eyes.

  • Do not let the model fly too far downwind. The smaller the model appears, the

more difficult it is to fly and orientation becomes more of a problem. Know the

limitations of your eyesight and always fly within ‘easy’ visual range.

4.3 Landing the Glider

  • Before launching, select your landing area. This should be free of obstructions

on the approach, which should always be into wind so as to reduce the speed of

the model over the ground.

  • If possible, avoid overflying other pilots’ transmitters as this may cause radio


  • Try to stay away from trees, buildings and other structures which may cause

turbulence, making the model difficult to control.

  • Be particularly vigilant for bystanders – especially children – who may be

unaware of the presence of the model as it lands.

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5 Electroflight

5.1 For electrically powered models, all the safe operating conditions described in

paragraph 1 apply. In addition:

  • When fast charging Ni-Cad or Ni-MH batteries, use a battery charger equipped with

either a timer or a voltage or temperature controlled cut-off. Overcharging Ni-Cad

or Ni-MH batteries at high currents can be dangerous.

  • Lithium Polymer (Li-po) batteries are also extremely susceptible to both

overcharging and over discharging. A charger designed specifically for charging

Li-po batteries must be used. Care should be taken to ensure that the batteries

are not discharged at current rates that are outside the manufacturer’s

recommendations as to do so can be dangerous.

  • Check carefully that motor operation does not interfere with the R/C equipment in

the model. A range check with motor on and off should be carried out with all new

installations. If in doubt, do not fly.

  • Current flows in the battery-controller-motor setup of electroflight models can be

extremely high. Make sure that all cables and connectors are in good order and are

robust enough to perform without significant overheating.

  • Take great care when handling any electroflight model that has its batteries fitted.

The power and torque of electric motors can be very high and contact between a

turning propeller and any obstruction will not stop the motor, but will just make it

try to turn harder.

6 Seaplanes

6.1 General

The classification ‘Aeroplane (Seaplane)’ includes floatplanes and flying boats,

both sometimes called waterplanes. The advice here also applies to amphibians

when operating on water.

There are fewer suitable sites for seaplanes than landplanes in the UK and generally

sites are also more restricted. The number of spectators is also much smaller. These

factors are taken into account before suggesting the following modified safety

considerations for seaplanes.

6.2 Seaplanes having a mass of up to 7 kg:

NO difference from landplanes of the same mass.

6.3 Seaplanes having a mass of over 7 kg and up to 20 kg:

Where conditions allow, and provided the model is flown along the line of the crowd

or away from them:

  • A minimum of 50 m separation should be maintained between the model in flight

and the people who are not involved in the operation of the model.

  • This distance may be reduced to 20 m for take-off or landing.
  • A distance of 10 m should be maintained while the model is taxiing. Taxiing

towards the crowd should be minimised.

  • All other requirements are the same as for landplanes.

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