Hazards CAAP 166
Aircraft size and performance – General aviation pilots should be aware that aerodromes with runways of 1400 m or more in length can accommodate jet or large turboprop aircraft operations. Runway lengths are published in ERSA.
For aerodromes with high-performance traffic in the circuit, the overfly height should be no lower than 2000 ft above aerodrome elevation.
Downwind take-offs and landings – Take-off or landing downwind is not recommended as a standard procedure. Pilots should use the runway most closely aligned into wind (the active runway), wherever possible.
Pilots must operate within the limitations prescribed in the aircraft flight manual (AFM), in accordance with CAR 138.
In accordance with CAR 92, pilots should consider the following hazards if planning to take off or land downwind:
- Wind strength just above ground level may be significantly higher than indicated by the windsock.
- Windshear (for take-off):
- higher groundspeed at lift-off
- a longer take-off distance required
- a shallower angle of climb
- degraded obstacle clearance
- in the event of an emergency, (landing straight ahead) touchdown will be at a higher groundspeed.
- Windshear (for landing):
- higher groundspeed at touchdown
- a longer landing distance required.
Wake turbulence and windshear – Wake turbulence is produced by all aircraft and can be extremely hazardous. Smaller aircraft should be aware that large aircraft produce strong/severe wake turbulence, with large jet aircraft producing extreme wake turbulence.
In calm conditions, wake turbulence may not dissipate for several minutes. Pilots should position their aircraft with sufficient spacing in the traffic circuit to avoid encountering wake turbulence.
On take-off, smaller aircraft will normally require increased separation time before departing behind a larger aircraft.
Helicopters of all sizes produce, in forward flight, vortices similar to those produced by fixed-wing aircraft. A hovering or slow air-taxiing helicopter creates a rotor downwash that can be a hazard to all nearby aircraft. Therefore, pilots of small aircraft should avoid operating close to helicopters. Equally, helicopter pilots should operate at a safe distance from parked or taxiing aircraft.
Windshear can occur anywhere in the traffic circuit, but is most dangerous when close to terrain. Dust devils (‘willy willies’) are visible windshear, common at outback aerodromes. Pilots encountering windshear should consider an immediate maximum-performance climb to fly out of the situation.
Take-off and landing separation
Take-off – When taking off behind another aircraft, pilots should adhere to the separation standards published in the AIP:
- wait until a departing aircraft has crossed the upwind end of the runway or has commenced a turn, and
- if the runway is longer than 1800 m, wait until the departing aircraft has become airborne and is at least 1800 m ahead
- if both aircraft have a maximum take-off weight less than 2000 kg, wait until the departing aircraft has become airborne and is at least 600 m ahead.
Landing – For a landing aircraft, the approach should not be continued beyond the runway threshold until:
- a preceding departing aircraft has commenced a turn or is beyond the point on the runway at which the landing aircraft could be expected to complete its landing roll and there is sufficient distance to manoeuvre safely in the event of a missed approach, or
- a preceding landing aircraft has vacated the runway.
Pilots should be vigilant when using another, non-active runway and ensure they do not create a hazard to aircraft using the active runway. Conversely, pilots using the active runway should ensure that aircraft operating on the non-active runway have held short or crossed the active runway before commencing a take-off or continuing to land.
Collision avoidance in the circuit
The most hazardous area for collisions is within a space bounded by a cylinder of airspace 5 nm in diameter and up to 3000 ft above aerodrome elevation. All pilots must maintain good situational awareness within this high-risk area.
Inbound pilots should minimise distractions within the cockpit. Passengers should be briefed not to distract the pilot unless there is imminent danger.
Pilots should be familiar with the aerodrome layout and have radio frequencies set, so their attention can be directed outside the aircraft. Pilots should be alert, looking for other traffic, maintaining a listening watch and responding appropriately to applicable transmissions. Pilots should broadcast their intentions by making the standard positional broadcasts and other broadcasts as necessary in the interests of safety.
Most collisions occur on downwind or on final approach. There are many distractions during this time, including configuring the aircraft, completing checklists, setting equipment and communicating. Early completion of checklists and configuration changes will help to minimise distractions at this critical time.
Good height and speed control (including use of flaps) is essential for maintaining separation during the approach. If adequate separation cannot be maintained, a go-around should be initiated sooner rather than later.
CARs 161 and 162 detail the rules and procedures for establishing right of way and preventing collisions. Pilots should have a sound understanding of these rules if giving way to, approaching head-on to, or overtaking, other aircraft.
The CARs are published at www.legislation.gov.au/Series/F1997B00935.
At aerodromes with both glider and helicopter operations, helicopter pilots should follow the standard traffic patterns to avoid gliders flying modified circuit patterns.
Maintaining separation in the vicinity of a non-controlled aerodrome
Increased collision risks exist at non-controlled aerodromes if instrument approaches are conducted at a time when visibility is reduced (by cloud, smoke or haze) but VFR conditions exist below the low-visibility layer.
In these situations, it is possible for a pilot flying an instrument approach through cloud to become visual and suddenly encounter a VFR aircraft in the circuit. Diligent radio broadcasting and continuous visual scanning are essential to avoid an airprox.
VFR pilots, on hearing IFR pilots broadcasting their intention to make an instrument approach, are expected to respond promptly to establish situational awareness with the IFR aircraft. Information that would be useful to the IFR pilot includes aircraft type, position and flight intentions.
VFR pilots should remember their responsibility to remain clear of cloud and maintain in-flight visibility in accordance with the criteria for visual meteorological conditions (VMC), as described in AIP ENR 1.2 and the VFRG.
Practice instrument approaches – pilots who wish to practise instrument approaches in VMC should be particularly alert for other aircraft in the circuit, so as to avoid impeding the flow of traffic.
Pilots flying IFR should give position reports in plain English so as to be easily understood by VFR pilots, who generally have no knowledge of IFR approach points or procedures. In general, positions should include altitude, distance and direction from the aerodrome. Details such as the outbound/inbound legs of an instrument approach, or area navigation fixes, will generally be of little assistance to VFR pilots in establishing situational awareness.