Safety Issue

On 2 December 2021, Civil Aviation Safety Regulation (CASR) Part 121 (Australian air transport operations – larger aeroplanes) and CASR Part 135 (Australian air transport operations – smaller aeroplanes) commenced. CASR 121.200 and CASR 135-175 both stated:

An aeroplane operator’s exposition must include procedures about conducting stabilised approaches to land at an aerodrome.

In December 2021, the Civil Aviation Safety Authority issued Acceptable Means of Compliance and Guidance Material for Part 121 and Part 135. The guidance material for CASR 121.200 and CASR 135-175 stated:

The regulation requires the exposition to include procedures concerning stabilised approaches. A stabilised approach is one during which several key flight parameters are controlled, within specified ranges, during the latter part of the approach. Conformance with established stable approach criteria is of equal importance to VFR and IFR flights.

The parameters include:

• aeroplane configuration
• flight path trajectory
• attitude
• rate of descent
• airspeed, and
• engine thrust or power setting.

In considering the numerical values of the parameters, operators should consult the flight manual and manufacturer sources in the first instance, considering areas such as what tolerances are provided in calculation data. For example, some flight manuals state that the landing distance calculations are dependent on the aircraft being flown in a specific speed range, and this varies between types. If nil flight manual/manufacturer guidance is available, operators may consider the parameters specified in the Part 61 MOS, Schedule 8, Table 2 ‘Aeroplane general flight tolerances – professional level’.

A stabilised approach has the effect of reducing pilot workload once stabilised, allowing a greater focus on flight path and airspeed, and it establishes the aeroplane at the optimal speed, position and attitude for the landing flare.

Conversely, pilot workload tends to increase if the above parameters are not stable when the aeroplane is approaching to land, allowing less time to focus on flight path and airspeed, and potentially leading to larger changes of attitude during the flare.

Some situations that reduce the likelihood of a stabilised approach include:

• circling approaches
• discontinuing an approach before the minima/MAPT to continue in VMC
• low level circuits.

These circumstances should be avoided when they are not operationally necessary, or where other more suitable procedures exist.

For many operators, the exposition procedures for a stabilised approach would require that:

• the aeroplane is in its planned approach/landing configuration
• all briefings and checklists have been completed
• the aeroplane is on the correct flight path (both laterally and vertically)
• the aeroplane is maintaining final approach speed (including guidance for turbulent air conditions)
• the maximum descent rate is not exceeded, and
• the power setting is appropriate to the aeroplane configuration.

The exposition should clearly define the minimum height at which the aircraft operation must meet the stabilised approach criteria. If applicable, the operator may elect to list more than one height when considering both IMC and VMC operations, for example:

• In instrument meteorological conditions (IMC), all flights would be stabilised by no lower than 1,000 ft above the aerodrome elevation.
• In visual meteorological conditions (VMC), all flights would be stabilised by no lower than 500 ft above the aerodrome elevation.

Go-around policy

Standard operating procedures should include the operator’s policy on the criteria for a mandatory go-around. This policy will normally require that, if an approach is not stabilised, or has become destabilised at any subsequent point after the minimum height during an approach, a go-around is required. Operators should reinforce this policy through training.