Certain transport aircraft will be required to carry a take-off performance monitoring system to reduce the persistent risk of data-entry and calculation errors, under a new proposal from the European Union Aviation Safety Agency.

The proposed mandate would only apply to new-build aircraft and would be unlikely to take effect until around 2033.

EASA’s measure is being driven by the long-standing threat posed by undetected deviation from expected take-off performance – a situation which can result from incorrect take-off parameters, using the wrong runway intersection, or misconfiguring the aircraft based on erroneous weight-and-balance data.

The proposed monitoring system would use three functions – designated F1, F2 and F3 – to detect problems and alert the crew.

EASA says the F1 function would check errors in take-off parameters, such as inputs to the flight-management system, while F2 would check the aircraft’s position at the beginning of the take-off run. The third function, F3, would provide real-time monitoring of take-off performance.

While the installation mandate for functions F1 and F2 would apply to all transport aircraft, the F3 function would only be required for large models – exempting smaller business jets and regional turboprops.

EASA justifies this preferred option by pointing out that the F3 function, real-time monitoring, is the “most complex and most expensive” of the three to implement.

While mandating all three functions could prevent 89% of potential future occurrences involving new aircraft designs, EASA says an analysis of previous incidents and accidents shows none involving smaller aircraft which would have been mitigated by the F3 function, but not by F1 or F2.

It says F3 offers “very limited benefits” for turboprops and executive jets – although business aircraft based on larger airliners would not be excluded.

EASA studied 118 occurrences worldwide spanning 1998-2023, which included 18 accidents – of which five were fatal – and 74 serious incidents.

While a retrofit of in-service aircraft is not being considered, the EASA proposal would apply to new-build airframes of already-certified aircraft types as well as new designs.

This would effectively double the number of compliant aircraft in the global fleet by 2058, some 25 years after implementation.

EASA is inviting comments on its proposals, setting a submission deadline of 3 October.