| 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 5 December 2018, a NOTAM was current for a displaced threshold (DT) at the western end of runway 29 (runway 11 threshold) for cable maintenance at Darwin airport, Northern Territory. A Fairchild Industries SA227, undertaking a passenger charter, conducted an intersection departure from taxiway E on runway 29 and passed low over the maintenance crew working on the upwind end of the runway. The intersection chosen for the departure was approximately at the midpoint of the runway, therefore significantly reducing the runway available.
Figure 1: Aerodrome Chart – Darwin, NT
Source: Airservices Australia, annotated by the ATSB
Pilot comments/considerations
The crew carried out calculations to determine that the aircraft could clear the obstruction described in the NOTAM. Their calculations demonstrated that the aircraft would be able to clear all obstacles even in the event of one engine failing during the take-off. Sufficient stopping distance was available for a rejected take-off (RTO) at low speed and actions required for an engine failure at or near V1[1] was to continue the take-off.
Airfield operators comments/considerations
- The NOTAM did not specify that aircraft can request any men and equipment to be vacated, however if an aircraft’s crew does request this, it can be done, but it is the exception rather than general practice.
- During DT operations ATC will:
- notify aircrew, through directed transmissions, of the DT or Reduced Operating Length (ROL) when issuing a landing/take off clearance.
- confirm if aircrew can accept a departure with the ROL that is in place, should they request an intersection departure.
Safety message
This incident highlights the need for pilots and ATC to be cognisant that when temporary changes to normal operations are in place, such as conditions in NOTAMS, increased vigilance is required.
Aircraft operation - Pilots and operators faced with unusual or changed circumstances should fully consider both their performance planning and decision-making processes. If any available option exists to enhance safe operations by increasing safety margins those options should be evaluated fully and applied if appropriate.
Airfield operators / ATC – if works are being undertaken within the runway environment it may be appropriate to restrict operations, for example, no or limited intersection departures. Alternatively, if an intersection departure is required, the maintenance crew should be advised and possibly vacated from the runway environment to provide necessary awareness and safety margins.
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.
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