Uncertainty assessment is an integral part of the monitoring and reporting guidelines.
Airlines are required to monitor tonne-kilometer data and fuel consumption over an annual reporting period to a maximum level of uncertainty of 2.5% for Tier 2 or 5% for Tier 1 operators.
Airlines must understand and identify possible causes of uncertainty of monitoring.
Airlines must take all necessary action to prevent missing data from occurring by implementing suitable quality control activities.
* Calibration certificates of on-board systems, National laws, Fuel suppliers' accuracy standards, Clauses in customer contracts, Routine checks