Quiet often, the dangerous take-off error is made before the aircraft moves whether a wrong weight, thrust setting or runway position entered into a computer that does not know it has been misled.
The European Union Aviation Safety Agency proposes requiring take-off performance monitoring systems or TOPMS, on certain newly built transport aircraft from 2033. The system would check whether performance figures and runway position make sense before take-off, then monitor the acceleration and progress of the take-off roll in real time.
The proposal is not a retrofit mandate for aircraft already in airline fleets. It would apply to new designs and to new-production aircraft of certain existing types. That is why the safety benefit builds slowly, even after the rule takes effect.
TOPMS is designed as three layers of protection. F1 is performance-parameter check which will check incorrect take-off data like thrust or speed calculated for the wrong weight, flap setting or runway. F2 entails position and heading check when an aircraft is beginning its take-off roll from wrong position or in the wrong direction. F3 is real-time performance check when actual take-off performance departing significantly, like acceleration is lower than expected because thrust, weight, drafg, braking configuration or runway conditions do not match the plan.
The first two checks would apply to all relevant transport aircraft. The third, real-time function would be required only for larger aircraft, because it is the most technically complex and costly function, and EASA found limited incremental safety benefit for smaller turboprops and business aircraft.
A TOPMS would not fly the aeroplane or automatically reject a take-off. Its value is an alert before V1, the decision speed at which stopping may no longer be safer than continuing. At that point, an unmistakable warning can turn an invisible calculation error into an operational decision.
EASA reviewed 85 investigated occurrences between 2007 and 2022 and found 13 incidents, 67 serious incidents and five accidents. In a wider historical study of 118 events from 1998 to 2023, it identified 18 accidents including five fatal accidents, and 74 serious incidents.
The agency classifies erroneous entry of aircraft-performance data as a Priority 1 safety issue for large aeroplanes. The risk is unusually stubborn because pilots may correctly follow a checklist while working from incorrect inputs. But most flight-management systems do not independently recognise that a plausible-looking value is wrong.
The UK Air Accidents Investigation Branch identified 32 similar take-off-performance events from 2017 to 2022. This is not a rare theoretical scenario. It is a recurring category of error in which ordinary cross-checking can miss a shared assumption.
EASA’s proposed timetable reflects the difference between designing a function into an aircraft and modifying one already flying.
For a new aircraft type, manufacturers can integrate software, sensors, flight-deck alerts, performance databases, certification evidence and crew procedures as part of the baseline design. But for old aircraft type, a retrofit can involve changes to avionics architecture, certification for each model and variant, modification kits, downtime, software configuration control, airline training and maintenance documentation.
EASA has therefore proposed a production-based approach rather than forcing airlines to retrofit every existing aircraft. The agency estimates non-recurring development and certification costs of around Euro 5 million for a business-aviation aircraft type and Euro 8 million for an airliner type.
EASA has not proposed a blanket rule for every airliner, turboprop, business jet or existing aircraft. Smaller business jets and regional turboprops would not need the F3 real-time monitoring function under the preferred option, although larger business aircraft derived from airliner designs may fall within scope.
Airbus already offers related functions which is called Take-Off Securing, or TOS on the A320, A330, A350 and A380 families. EASA says implementation across those fleets varies by function, from 20% to 100%, with sub-functions both installed in production and retrofitted.