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Operations at non-
towered aerodromes
d,Be heard, be seen, be safe:
carry & use your radio
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The inormation contained in this booklet was correct at the time o
publishing, and is subject to change without notice. CASA makes no
representation as to its accuracy. This booklet has been prepared by
CASA Saety Promotion or inormation purposes only.
Plan your route thoroughly, and carry current charts and documents.
Always check ERSA, NOTAMs, and the weather, BEFORE you y.
© 2010 Civil Aviation Saety Authority 1004.1262
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Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1 Limitations o see-and-avoid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2 New circuit procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3 Radio rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Bibliography. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Contacts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
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IntroductionFrom 3 June 2010, you will have to carry and use a radio
i you are ying at or in the vicinity o a certifed, registeredor military aerodrome that is non-towered. Some circuit
procedures will change or all non-towered aerodromes.
The changes are aimed at reducing the risk o mid-air
collisions by maximising separation at aerodromes without
air trafc control services. They are enshrined in amendments
to Civil Aviation Regulation 166 and supporting Civil Aviation
Advisory Publications, CAAPs 166-1(0) and 166-2(0).Certifed aerodromes have runways capable o handling aircrat
with more than 30 passengers or 3,400kg o cargo. They are used
by regular public transport, charter and GA aircrat. Registered
aerodromes have lower minimum operating standards than certifed
aerodromes. Military aerodromes are controlled by the Australian
Deence Force, and, as in the past, you need permission to land.
By defnition, non-towered aerodromes are in uncontrolled, Class Gairspace. When air trafc control is not operating, towered aerodromes
come under the rules o non-towered aerodromes regardless o which
airspace they are normally in.
CASA might at times ‘designate’ uncertifed and non-registered aerodromes
at which carriage o radio will also be required. We will publish the names o
designated aerodromes in the En-route Supplement Australia (ERSA) and/or
NOTAMS.
The rule changes coincide with the replacement o general aviation airport
procedures (GAAP) with Class D airspace. They come amid mounting evidence
or limits to the see-and-avoid principle. Many accidents and incidents could have
been prevented by the carriage and use o radio. Radio communication heightens
situational awareness. It enhances visual scans by telling you where to look or other
aircrat. Experts estimate that you are eight times more likely to see a threat aircrat i
you use a radio.
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This ‘alerted see-and-avoid’ philosophy
underlies the rule changes, and will
be supported by an extensive auditingand surveillance campaign. It comes as
trafc at many non-towered aerodromes
increases, with the Dash 8 and even
Boeing 737 aircrat o regular public
transport sharing the circuit with the
Cessna 172s and ultralights o general
aviation. The wide range in the types and
perormance o aircrat converging on
aerodromes, and in the experience o the
pilots ying them, heightens the risk o
mid-air collisions.
Another problem is a practice that is the
worst-kept secret in aviation—sneaking
into aerodromes unannounced in order
to evade landing ees. The practice ails
rational cost-beneft analysis, given thatlives are at stake and landing ees, trivial.
This booklet should be read in conjunction
with CAAP 166-1(0) and CAAP 166-2(0),
which outline the rule changes and advise
on a code o conduct and good airmanship
practices at non-towered aerodromes.
It covers: the limitations o the see-and-avoid principle. It also outlines the
new circuit and radio communications
procedures, and gives hints on ways to
enhance the saety o everyone operating
at non-towered aerodromes.
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1 Limitations of see and avoid
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Although mid-air collisions are rare, horrorstories o near misses abound. In one
incident, in NSW in 2009, an aeroplane
came within 150m o a helicopter.
Such incidents could have been avoided
had pilots been using radios to hone visual
scans or trafc.
On 20 May 1988, the worst didoccur. A Cessna 172 collided with a
Piper Tomahawk in the circuit area o
Coolangatta aerodrome in Queensland,
killing our people, according to the ATSB.
The accident, which happened in
conditions o good visibility, underlined the
shortcomings o visual scans, and provided
the impetus or the ATSB report Limitations of the see-and-avoid principle .
Private pilots on VFR ights spend
about hal their time scanning or trafc,
according to research cited in the report.
Airline pilots possibly devote less time to
scans.
Ergonomic, physiological, behaviouraland environmental actors limit the
eectiveness o visual scans, however,
regardless o how long you spend on them.
‘Most cockpit windscreen confgurations
severely limit the view available to the
pilot,’ the report says.
Window posts, windscreen bug splatter,sunvisors, wings and ront seat occupants,
obscure the view.
‘Window posts, windscreen crazing anddirt can act as ocal traps and cause the
pilot to involuntarily ocus at a very short
distance ...,’ the report adds. ‘Direct glare
rom the sun and veiling glare reected
rom windscreens can eectively mask
some areas o the view.’
And scans are typically unsystematic,
with attention ocused on the view romthe centre o the windscreen. A thorough,
systematic search ‘is not a solution as in
most cases it would take an impractical
amount o time’, the report says.
Compounding these problems are
physiological actors.
One is the blindspot in the eye, where theoptic nerve exits the eyeball.
Yet another problem is ‘empty feld
myopia’. ‘In the absence o visual cues,
the eyes ocus at a resting distance o
around hal a metre,’ the report says. ‘An
object which is smaller than the eye’s
acuity threshold is unlikely to be detectedand even less likely to be identifed as an
approaching aircrat.’
Peripheral vision is aected by increased
workload, atigue and stress as i busy
pilots are ‘unknowingly wearing blinkers’.
Meanwhile, moving objects are easier
to see than stationary ones, but, in mostcases, ‘an aircrat on a collision course
appears as a stationary target in the pilot’s
visual feld’.
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Another physiological limitation is the time
it takes the eye to ocus as our muscles
move to alter the shape o the lens. Itprobably takes the average pilot several
seconds to shit their ocus to a distant
object, and the process can be aected
by atigue.
Poor contrast is another problem, with
aircrat ading into the background. It is
also difcult to pick out an aircrat against
a complex background o sky and terrain.
‘An approaching aircrat in many cases
presents a very small visual angle until a
short time beore impact,’ the report adds.
Even i a pilot does see an approaching
aircrat, there ‘is no guarantee that evasive
action will be successul’.
‘It takes a signifcant amount o time to
recognise and respond to a collision threat
and an inappropriate evasive manoeuvre
may serve to increase rather than
decrease the chance o a collision.
‘Because o its many limitations, the see-
and-avoid concept should not be expected
to ulfl a signifcant role in uture air trafcsystems,’ the report concludes.
Despite the change in emphasis in the
revised rules, you should maximise
the eectiveness o scans. Clean your
windscreen, and ree up time or scanning
when it is most needed by managing your
ight to minimise cockpit workload on
approach and landing.
Use a rigorous scanning technique. In
variations on the widely used ‘block’
method, the pilot successively fxes onthe centres o blocks o 10 to 15 degrees
across the horizon and 10 degrees above
and below it, according to the Air Saety
Foundation.
The ‘side-to-side’ block scan starts at one
side o the aircrat and steps block-by-
block to the other. The ront-to-side scan
starts at the centre, working out to oneside beore returning to the centre and
covering the other side.
The technique has limitations, however,
and you should check or overtaking
aircrat every ew scans, the ASF says.
Meanwhile, radio will sharpen your ability
to spot aeroplanes closing in on you.
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Side-to-side scanning methodStart at the left of your visual area and make a methodical sweep to the
right, pausing in each block of viewing to focus your eyes. At the end of the
scan, return to the panel.
Front-to-side scanning methodStart at the centre block of your visual eld (centre of front windshield);
move to the left, focusing in each block then swing quickly back to the
centre block after reaching the last block on the left and repeat the
performance to the right.
Figure 1 Block system scanSource: AOPA Air Saety Foundation
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On 7 July 2009, an aeroplane came within 150m o a Kawasaki
helicopter on approach to Moree aerodrome in NSW. The aircrat
was at the same level as the helicopter at the time o the incident.
It had not made a broadcast on the CTAF requency.
Communication breakdown
During the climb rom Wollongong aerodrome on 21 January 2001, the
pilot o a Cessna 206 heard engine noise and looked up to see a Cessna
172 pass less than 10t above. The pilot o the C-206 reported that
he had made the appropriate radio broadcasts on the CTAF requency.
However, the C-206 was at the CTAF boundary, and the pilot o the
C-172 was operating on the area requency. The pilot o the C-206 noted
that both pilots heard the other aircrat pass beore seeing each other.
As the pilot o a Beechcrat KingAir was joining crosswind leg or runway
06L at Jandakot Aerodrome, Western Australia on 9 November 2001, a
Cessna 172 passed rom let to right between 10 and 15m in ront. The
pilot o the KingAir had no time or evasive action but widened the circuit,
and tried to make radio contact with the aircrat. The crew o the KingAir
had not heard any transmissions on the MBZ requency rom the Cessna.
The C-172 departed to the south and the KingAir made an uneventul
landing. CASA was advised o this occurrence.
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Several radio calls made on the MBZ by two inbound aircrat ailed to
elicit a response rom a VFR Cessna 172 departing Williamtown Airport
in NSW on 25 November 2001. The Cessna started its takeo roll as
an inbound Beech 1900 was joining crosswind. The pilot o the Beech
carried out an avoidance manoeuvre to join mid-crosswind. Another
regional aircrat was on fnal when the departing Cessna passed
behind and approximately 600t above.
The pilot o a Cessna 172 was conducting dual training circuits o runway 28
at Archerfeld aerodrome in Queensland on 7 May 2002 under MBZ procedures
as the tower closed. On the student’s ourth circuit turning downwind, a Beech
36 (Bonanza) passed nearby rom right to let. The Cessna had not heard any
inbound transmission or circuit joining call rom the Bonanza. The instructortook over the controls and descended to about 800t to let the Bonanza y
across and above. The Bonanza joined downwind at 1,000t without giving way
to trafc already in the circuit. When asked i he had seen the Cessna, the pilot
said, ‘not until the last minute’.
While passing 1,400t on climb on upwind with a simulated
engine ailure rom Broome Aerodrome, Western Australia,
on 23 July 2003, a Cessna 402 crew saw a Cessna 210
descending about 300t above and 50 metres in ront. TheC-210 pilot’s previous transmissions o the aircrat’s position
and intentions had been inaccurate.
Source: ATSB 10 11
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2 New circuit procedures
Check the En-route Supplement Australia(ERSA) to see i aerodromes you intend
using are certifed, registered or military,
and thereore subject to the new rules that
require radio carriage and use.
The usual let circuit pattern is retained in
the revised CAR 166 rules unless stated
otherwise in ERSA or by NOTAM.
The standard circuit heights and spacings
that were introduced as part o the NAS2C
airspace reorms in 2005 have been
retained or the dierent aircrat types in
order to maximise segregation.
radio carriage MANDATORY
at all CERT, REG, MIL aerodromes
radio carriage NOT MANDATORY
at UNCR aerodromes unless
required by the aerodrome operator
or designated by CASA.
FOR ILLUSTRATIVE PURPOSES ONLY
Figure 2 How mandatory radio carriage is depicted in ERSA
However, the treatment o aircratperormance parameters has been
tweaked. High perormance aircrat—jets,
and many turboprops with a standard
circuit speed above about 150kt should y
at 1500t above the aerodrome.
Medium perormance aircrat, such as
most piston-engined GA aircrat with
circuit speeds between 55kt and 150kt,should y at 1000t.
Low perormance aircrat—some sport
aircrat such as microlights and gyroplanes
with a circuit speed under 55kt—should
y a standard circuit height o 500t.
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Joining the circuit on base leg is allowed
but not recommended. You must assess
the trafc levels and suitability beoreyou join as you must give way to other
trafc and join without conict. You should
broadcast your intentions, know the wind
speed and direction, and the circuit pattern
in use.
The circuit Ater take-o, during the climbout, make
the turn onto crosswind at a height that
allows you to arrive on downwind at the
circuit height. You should not be less than
500t above the aerodrome.
High perormance turbo-props and jets y
a wider circuit at 1,500t whereas medium
and low perormance aircrat ying a
1,000t and 500t circuit respectively will
y a tighter circuit.
Departing the circuitDepart the circuit area by extending one o
the our standard circuit legs. Only whenyou are well outside the circuit area, and
no trafc conict exists, can you make a
turn opposite to the circuit direction. This
would normally be at least 3nm rom the
circuit, but it could be less or aircrat with
high climb perormance.
Joining the circuitI you are unamiliar with an aerodrome’s
layout, circuit direction or conditions,overy or circle it at least 500t above the
circuit altitude. Where high perormance
aircrat could be operating, this will usually
be at 2,000t above the aerodrome
elevation. Once you have determined the
circuit direction you can descend on the
non-active (dead) side o the circuit.
Low perormance aircrat such as
ultralights, and some rotorcrat with a
maximum speed o about 55kt should
overy midfeld at 500t above the
aerodrome.
We recommend you join the circuit on
downwind leg, either rom an extension
o the downwind leg, a 45 degree angleabout halway down downwind, or rom a
shortened crosswind leg which takes you
over the runway.
Straight in approaches are allowed but not
recommended. They require you to assess
the trafc levels and suitability to ensure
that you do not conict with other circuittrafc and that no reciprocal runway is in
use. You must know the wind direction and
speed, and be established on fnal by 3nm.
Broadcast your intentions.
eight th
ind at t
e less t
d jets y
medium
ill
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Joining circuit
on a base leg
Arriving at not less
than 500ft above
circuit height
Joining at 45º
Arriving at not
less than 500ft
above circuit
height
Joining circuit
at crosswind
Joining for straight
in approach not
less than 3nm
D e s c e n d
t o
c i r c u i t h e i g h t
D o wn wi n d l e
g
F i n a l
Crosswind leg
Base leg
Joining circuit on
a downwind leg
Recommended circuit join
Figure 3 Aerodrome trafc circuit showing arrivals and joining
ning at 45
than 500ft abo
circuit height
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3 Radio rules
When at or near a non-towered aerodrome, check that your radio is on thecorrect requency, and listen to the broadcasts. Under CAR 166 C, you must
make a radio broadcast whenever it is reasonably necessary to avoid a
collision or the risk o a collision.
For minimum compliance, you should broadcast your intentions:
beore or during taxiing
immediately beore entering a runway, whether
active or not
inbound 10nm or earlier rom the aerodrome
immediately beore joining the circuit
on a straight-in approach, on fnal, by 3nm rom
the threshold
on a base-join approach, beore joining on basewhen ying near, but not intending to land at, a
non-towered aerodrome, where the pilot intends to
y through the vicinity but not land.
But use your radio more often if needed.
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When making radio calls state the name
o the aerodrome, your aircrat’s type,
call sign and position, and your intention.Repeat the name o the aerodrome. Use
standard phraseology and don’t chat.
I you are ying VFR, identiy yoursel i
you hear an IFR pilot intending to make an
instrument approach. I you are ying IFR,
report your position and intentions in plain
English, not as IFR approach points, which
VFR pilots might not know.
As needed, make other broadcasts such
as:
turning: downwind base and fnal
clear o runway.
The collision avoidance systems TCAS and
ACAS are other methods o alerted see-
and-avoid. I you are ying a GA aircratand have a transponder, turn it on so that
RPT aircrat equipped with TCAS and
ACAS know where you are.
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Bibliography
CAAP 166-1(0) Operations in the vicinity of non-towered (non-controlled) aerodromes ,
CASA, 2010
CAAP 166-2(0) Pilots’ responsibility for collision avoidance in the vicinity of non-
towered (non-controlled) aerodromes using ‘see-and-avoid’ , CASA, 2010
Limitations of the see-and-avoid principle , ATSB, 1991
Operations at non-towered aerodromes (DVD), CASA Aviation Saety Promotion, 2010
Look out! Situational awareness , (DVD) CASA Aviation Saety Promotion, 2009
AOPA Air Saety Foundation, ‘Collision avoidance strategies and tactics’, Safety
Advisor , Operations and Profciency No. 4 http://www.aopa.org/as/publications/
sa15.pd
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CASA contacts
PHONE: 131 757
EMAIL: [email protected]
WEB: www.casa.gov.au/nta/
CASA GPO Box 2005 Canberra ACT 2601
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