Definition
Flight Technical Error is the difference between the aircraft's actual position and the position commanded by the navigation system, as measured by how well the pilot or autopilot follows the displayed course. It reflects how accurately the flight crew or autoflight system tracks the desired path shown on the flight instruments, and is one of the three components that make up Total System Error in Required Navigation Performance (RNP) operations.
Plain English
How far off the displayed course the aircraft drifts because of how the pilot or autopilot is flying it. Even if the navigation system knows exactly where the aircraft is and where it should be, the pilot or autopilot still has to steer it onto that line — and FTE is the small error in doing that.
Context Anchor
Seen in required navigation performance discussions, especially where the handbook explains how total navigation error is made up of different parts.
Derivation
‘Technical’ here refers to the technique of flying — the hands-on (or autopilot-on) act of keeping the aircraft on the commanded path. So Flight Technical Error literally means the error introduced by the act of flying itself, separate from any error in the navigation equipment or its position estimate.
Why Pilots Care
Excessive FTE can push the aircraft outside RNP containment limits, triggering alerts or requiring a missed approach.
Grounding Statement
If the displayed path is the line you are trying to follow, flight technical error is how far your actual flying strays from that line.
Intuition Check
Do not read “error” here as only a careless mistake. In this context, it means a measurable difference between the intended flight path and the path actually flown.
Example Sentence 1
On the RNP approach, the captain hand-flew the segment carefully to keep flight technical error small and stay well inside the required containment limits.
Example Sentence 2
The pilot reduced FTE by tightening bank-angle corrections during the final approach segment.