Erroneous Take-Off Performance Data

There have been a number of incidents in recent years involving incorrect take-off performance parameters. During their investigations, the Accident Investigation Boards (AIBs) identified the need for Regulators and Operators to launch actions to mitigate the risk of this safety issue.  Erroneous take-off performance parameters refers to the introduction of errors during the calculation and entry of take-off performance related parameters into aircraft Flight Management Systems (FMS) and other related systems (such as Electronic Flight Bags). 

In the longer term, aircraft software and systems will provide hard barriers against erroneous data entry.  These solutions will take some time to reach the cockpit and in the meantime it is important that operators take practical measures to remind their flight crews of this safety issue and ensure that it is suitably covered both training and operational procedures.  

The Risk of Erroneous Take-off Data  

Systematic and routine preflight planning does not guarantee that a take-off will be uneventful. Prior to any flight, pilots are occupied with different tasks, checks and calculations. There is a high potential that interruptions and distractions during this time could divert the flight crew’s attention and potentially lead to the entry of incorrect flight parameters in the aircraft’s cockpit systems. Pre-flight tasks are often performed under time pressure and when flight crews may have accumulated fatigue from previous flights. Pilots or flight operations staff may also be provided with erroneous data such as weight and center of gravity which they use to perform calculations.

A small mistake in calculating values or entering the wrong parameters in the aircraft systems, FMS or Electronic Flight Bag (EFB) could lead to an error in the take-off distance, the thrust and speed, or trim setting required for take-off, all with potentially catastrophic consequences.  Crews need to be aware of the risks while operators should maximise support to pilots during this critical phase of flight.   
The reporting of events is equally important and pilots are encouraged to report events related to erroneous data entry as part of the organisation’s Safety Management System (SMS).  These reports help operators to better understand the challenges and to effectively mitigate risk. These mitigations will cause operational procedures to be optimised. As part of this optimisation, flight crew should be made aware of new occurrences so that everyone in the airline can learn from the experience of others.  

The Safety Manager View – What Your Organisation Should be Thinking About?

As a Safety Manager there are a number of things that you should be asking yourself and your team with respect to erroneous take-off data. 

  • Is erroneous take-off data a risk to your organisation?  What is the data from your reporting system saying? 
  • If it could be a safety issue, is it captured in the SMS?  Are there any mitigations in place?
  • Does the organisation actively encourage the reporting of occurrences involving this issue, and are these occurrences thoroughly investigated to identify possible organisational and human factors? Are the results of the investigations used to identify and strengthen weak barriers in the SMS?
  • Are there alerts within the Flight Data Monitoring (FDM) system and has the organisation identified performance indicators in the reporting system and are they regularly monitored?
  • Are relevant and robust procedures in place to mitigate against the risk of erroneous take-off data?
  • Are open discussions about the risk of erroneous take-off data encouraged by the organisation?  
  • Is the impact of time pressure and fatigue on flight crew considered with respect to this risk?  

EASA has produced a video to assist your organisational discussions on this subject and to increase flight crew awareness of the issue.  The Erroneous Data Parameters video by Together4Safety illustrates this key aspect of flight safety and outlines 5 key practices that flight crews can follow to reduce the likelihood of using erroneous take-off data. 

Flight Crew – Good Practices to Follow

Pilots flying for an airline or other fixed-wing commercial operator should watch the video and consider these key points: 

  1. Give yourself enough time to perform calculations and enter data into the Flight Management System; beware of distractions;
  2. FMS data entry should be slow and deliberate to ensure that the data entered reflects your intentions;
  3. Double check data that has been entered to ensure consistency;
  4. The FMS in most aircraft will not alert the pilot if there is an incorrect entry. So check the FMS to detect unrealistic values and significant errors;
  5. If the take-off is abnormal, react promptly.  Depending on the situation, reject the take-off or apply TOGA.  If necessary delay rotation.   

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