| 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 at approximately 1800 Eastern Daylight-saving Time, a Boeing 737-800 carrying 155 passengers was approaching Sydney, New South Wales from the north. Due to an oversight in planning and briefing for the approach, an incorrect waypoint crossing altitude was entered and the crew did not notice that the aircraft was high on profile for much of the initial descent. The crew noticed the discrepancy at approximately 30 NM, and took action to rectify the profile. Despite earlier than normal speed limitations from ATC due to slower preceding traffic on the same runway, the profile was not regained which lead to the aircraft remaining consistently high on the final approach profile.
The aircraft was above glideslope and descending on autopilot to 2,600 ft, when approaching the set altitude, the crew selected 3,000 ft on the autopilot in preparation for a potential go around. Due to the autopilot mode, this resulted in a thrust increase and the aircraft pitched up and commenced climbing to 3,000 ft. The crew decided to conduct a go around, during which the aircraft pitch changed and an accompanying decay in airspeed continued to a point that the warning “airspeed low” sounded. At approximately the same time as the crew received the warning they noted the low airspeed and ensured increased thrust was applied. The crew addressed the pitch attitude and as airspeed stabilised and flap was retracted, the go around was carried out according to the published procedure. The crew completed the required checklists and made a cabin announcement as the aircraft was vectored for a subsequent approach and landing.
Safety message
This incident highlights the need for crew to make early positive decisions to regain the required performance or profile when operations are not normal. Making a positive early decision may assist in avoiding forced decisions later when there is less margin for error. It is important to recognise the compounding effects that non-standard operations can produce, and that increased vigilance is required to successfully manage the situation.
Comprehensively pre-briefing a procedure and then monitoring progress is an effective way to minimise mistakes and recognise early that desired performance is not being achieved. Once a departure from the desired performance is recognised, a positive corrective action should be taken.
If ATC instructions are affecting your ability to meet the desired performance – speak up. An orbit or a vector for more track miles in a similar situation may be preferable to a forced go-around or missed approach.
The ATSB SafetyWatch highlights the broad safety concerns that come out of our investigation findings and from the occurrence data reported to us by industry. One priority is Data input errors.
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.