Erroneous takeoff performance calculation, Boeing 777

Takeoff with lower than required thrust setting leads to safety risks

Takeoff performance occurrences are a special group within the takeoff occurrences. They are not limited to specific aeroplane types or flight operations. They stand out because of the absence of a proper warning system and because the outcome of the majority of these occurrences is without damage or loss of life. The outcome of a performance occurrence can be catastrophic though, but luckily until now most of them resulted in the aeroplane just getting airborne before the end of the runway. As the outcome of those occurrences is often without consequence, one might tend to believe that the problem is not that serious.

Past occurences

In March 2018, the Dutch Safety Board published the report Insufficient thrust setting for takeoff. This report analyses two serious incidents involving an insufficient thrust setting for takeoff. The Board recommended in this report to European Union Aviation Safety Agency (EASA) among others to start the development of specifications and the establishment of requirements for Takeoff Performance Monitoring Systems without further delay. In the first quarter of 2020, this recommendation was under review by EASA.

Investigation reports of state accident investigation agencies on takeoff performance occurrences show that in the past decades the airline industry has made efforts to improve the operational procedures to prevent incorrect takeoff thrust settings. However, these efforts have not resulted in a significant reduction of the risk, as takeoff performance occurrences are still encountered on a regular basis. Therefore it is urgent, as this occurrence once again shows, to introduce new systems that are fully integrated in the cockpit and among others provide a timely alert to flight crew when the achieved takeoff performance is inadequate for the given aeroplane configuration, actual weight and
balance and aerodrome conditions. In 2018, Airbus developed a function on the A380 which is now also available on the A350, called Takeoff Monitoring (TOM), which warns a crew of abnormally low takeoff acceleration. This kind of systems should become part of the global commercial fleet.

Recommendations

To European Union Aviation Safety Agency and the Federal Aviation Administration:

To take the initiative in the development of specifications and, subsequently, develop requirements for an independent onboard system that detects gross input errors in the process of takeoff performance calculations and/or alerts the flight crew during takeoff of abnormal low accelerations for the actual aeroplane configuration as well as insufficient runway length available in case of intersection takeoffs. Take this initiative in close consult with the aviation industry, including manufacturers of commercial jetliners amongst which in any case The Boeing Company.

To International Air Transport Association:

To develop a standard policy for airlines with regard to procedures for reduced thrust takeoffs, including a risk analysis addressing cost reductions versus introduced safety risks.

To The Boeing Company:

For the existing and future commercial aeroplanes, to research on and develop an independent onboard system that detects gross input errors in the process of takeoff performance calculations and/or alerts the flight crew during takeoff of abnormal low accelerations for the actual aeroplane configuration as well as insufficient runway length available in case of intersection takeoffs.

To International Civil Aviation Organization:

To note the conclusions of this report and introduce provisions addressing an independent onboard system that detects gross input errors in the process of takeoff performance calculations and/or alerts the flight crew during takeoff of abnormal low accelerations for the actual aeroplane configuration as well as insufficient runway length available in case of intersection takeoffs.