In a recent Safety Alert for Operators (SAFO), the FAA expresses concern that ETA time estimates provided by pilots in oceanic control areas (CTAs) are “less accurate than expected,” particularly when adverse weather causes pilots to deviate from the planned course. “These inaccurate estimates can compromise the separation of aircraft,” the agency says.
When a time estimate is found to be greater than the time prescribed by the appropriate ATC authority, a revised estimated time should be sent as soon as possible to ATC. This prescribed time might differ by region. In the North Atlantic, for example, the standard is “three minutes or more.”
The SAFO suggests a reliable way to maintain an accurate ETA in the FMS. In addition, pilot position report ETAs need to be compared with the original operational flight plan ETA and other operational parameters—such as distance to waypoint, airspeed and winds—to ensure timing accuracy.
