| Occurrence Briefs are concise reports that detail the facts surrounding a transport safety occurrence, as received in the initial notification and any follow-up enquiries. They provide an opportunity to share safety messages in the absence of an investigation. |
What happened
On 19 January 2019, the pilot of a Piper Aircraft Corp PA-28-161 departed Bankstown, New South Wales (NSW), to conduct a return solo training flight to Taree, NSW. The weather en-route at the time of departure included low cloud and reduced visibility. The adverse weather and amended flight plan options were discussed with the instructor prior to departure.
On the return leg to Bankstown, the pilot observed cloud building along the coast and en-route. When the aircraft reached Anna Bay, 23 km east of Williamtown Aerodrome, NSW, the pilot attempted to descend below cloud to remain visual, but was unsuccessful due to the low cloud coverage resulting in the pilot climbing back to 1,500 ft above mean sea level (AMSL). At this stage, the cloud cover was overcast[1] with base approximately 600 ft AMSL and tops of 1,500 ft AMSL.
Air traffic control (ATC) contacted the pilot to determine why the aircraft was descending and climbing. The pilot advised ATC that he was trying to get below the cloud but was unable. ATC advised the pilot that further adverse weather was at the destination and provided options to divert to an alternate landing area. The pilot declined the diversion and elected to continue to Bankstown. Shortly after, the pilot asked ATC for further assistance and requested a suitable alternate landing area. ATC advised that Williamtown Aerodrome, NSW was available with favourable weather.
The pilot accepted the diversion and ATC instructed him to track east of Williamtown, over the coast and climb to 2,400 ft. Once over the coast, ATC further instructed the pilot to descend through cloud to 500 ft. ATC further assisted the pilot with instructions to keep wings level, to trust the artificial horizon[2], not to exceed 1,000 ft per minute rate of descent while in cloud to prevent spatial disorientation and to control a stable descent.
As the aircraft descended through cloud, the pilot became visual over the water at 600 ft AMSL. The pilot then advised ATC that he was out of cloud and visual with ground and water. ATC issued a clearance to track direct to the aerodrome.
Visual Meteorological Conditions (VMC) requirements
Table 1: VMC criteria for aeroplanes below 3,000ft above mean sea level
| Class of Airspace | Flight Visibility | Vertical and Horizontal distance from cloud | Conditions |
| Class G (Uncontrolled) or within 1,000 ft of ground |
5,000M | Clear of cloud and in sight of ground or water | Radio must be carried and used on the appropriate frequency |
| Class D (Controlled) |
5,000M |
600M horizontal 1,000FT vertically above cloud Or 500FT vertically below cloud |
ATC may permit operations in weather conditions that do not meet these criteria (Special VFR). |
Source: Aeronautical Information Publication (AIP) Australia: ENR 1.2-4 10 November 201
Safety message
Pilots are encouraged to make conservative decisions when considering how forecast weather may affect their flight. If poor weather is encountered en-route, timely and conservative decision making may be critical to ensuring a safe outcome.
VFR[3] pilots are also encouraged to familiarise themselves with the definition of VMC criteria and carefully consider available options where forecast or actual conditions are such that continued flight in VMC cannot be assured.
Flying with reduced visual cues and Inflight decision making such as in this occurrence remains one of the ATSB’s major safety concerns.
Number 4 in the Avoidable Accident series published by the ATSB titled ‘Accidents involving pilots in Instrument Meteorological Conditions’ lists three key messages for pilots:
- Avoiding deteriorating weather or IMC[4] requires thorough pre-flight planning, having alternate plans in case of an unexpected deterioration in the weather, and making timely decisions to turn back or divert.
- Pressing on into IMC conditions with no instrument rating carries a significant risk of severe spatial disorientation due to powerful and misleading orientation sensations in the absence of visual cues. Disorientation can affect any pilot, no matter what their level of experience.
- VFR pilots are encouraged to use a ‘personal minimums’ checklist to help control and manage flight risks through identifying risk factors that include marginal weather conditions.
About this report
Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.
__________
- Overcast - Overcast or overcast weather, as defined by the World Meteorological Organization, is the meteorological condition of clouds obscuring at least 95% of the sky.
- Artificial Horizon - Is a flight instrument that informs the pilot of the aircraft orientation relative to Earth's horizon, and gives an immediate indication of the smallest orientation change.
- Visual Flight Rules
- Instrument meteorological conditions (IMC): weather conditions that require pilots to fly primarily by reference to instruments, and therefore under Instrument Flight Rules (IFR), rather than by outside visual reference. Typically, this means flying in cloud or limited visibility.