Serious Incident  G-JZHL

2022-018: It is recommended that the UK Civil Aviation Authority, in conjunction with other regulatory authorities, develop a set of technical specifications and, subsequently, develop certification standards for an on-board system that will alert the crew of an aircraft to abnormally low acceleration during take-off.

EASA have published their NPA 2025-01 (RMT.0741) which the whole of the EUROCAE / RTCA group were encouraged to read and comment back on before the deadline of 03rd October 2025.

The joint EUROCAE / RTCA working Group (WG129 SC244) continues to hold weekly working meetings and quarterly plenaries to progress the Take off Performance Awareness and Alerting System (TOPAAS) MOPS document we have started since the acceptance of our Internal report which confirmed the maturity of the current technology.

We have recently attended Plenary no 9 which also includes the 4 plenary meetings which we used for the production of the internal report for the TAC. During this last meeting the group agreed to an extension to the deliverable date as progress with the MOPS had not been as expedient as we had hoped. Our revised date which we are requesting of the TAC for publication of the MOPS is March 2027. With this timeframe, we continue to push for a mature draft document by September 2026.

Adequate – Open

October 2026

2022-019: It is recommended that the UK Civil Aviation Authority encourage all UK Air Operator Certificate holders to implement into their flight data monitoring programme algorithms to detect the precursors relevant to the monitoring of take-off performance detailed in the European Operators Flight Data Monitoring Document, Guidance for the implementation of flight data monitoring precursors.

In response to the recommendation from this serious incident the CAA will engage with stakeholders and regulatory bodies to identify parallel workstreams and seek to maximise the safety benefit of FDM programmes.

The CAA has continued its engagement with industry through various working groups such as the Flight Ops Liaison Group (FOLG) to emphasise the importance of effective flight data monitoring programmes to identify take-off performance related events, particularly abnormally low acceleration during take-off.

Furthermore, to support and ensure wider dissemination of the message, the BALPA Flight Safety Committee was provided with a detailed briefing of the CAA’s ongoing work in this area.

Analysis was also undertaken by our Safety Intelligence team, which reviewed four years of historical flight data provided by a single operator to determine the optimal point on the take-off roll to capture acceleration. In collaboration with the operator, the aim was to identify any low acceleration outliers, investigate the causes and detect any trends associated with certain locations, runways or aircraft.

The study concluded that the CAA is not in a position to specify a single value for operators to incorporate within their Flight Data Monitoring programmes, but the results showed the most appropriate point for capturing acceleration lies between the range of 80kts and peak acceleration. While the analysis provided an indicative range for the optimal point of acceleration capture, it also highlighted that some events could be missed or hidden depending on the statistical analysis tools used. It is therefore recommended that each operator determines, validates, and continually refines their own alerting criteria to ensure optimal data capture for their specific operation.

The aim is to encourage operators to apply statistical modelling to this data and identify any outliers and instances of low acceleration that fall outside three standard deviations from the mean and conduct further investigations.

To conclude Safety Recommendation 2022-019, the Civil Aviation Authority proposes to formally document the above findings by means of a Safety Notice. It will require operators to reviewing the effectiveness of their Flight Data Monitoring programme in this area.

Adequate – Open

May 2026