“LTE is a critical; low-speed aerodynamic flight characteristic which can result in an uncommanded rapid yaw rate which does not subside of its own accord and, if not corrected, can result in the loss of aircraft control.” - AC90-95
Key points:
Pilot feels an uncommanded yaw towards the advancing blade
It is an aerodynamic condition, not mechanical failure
Flow of air over tail rotor is altered
Contributing factors:
Turbulence
High power setting
Slow forward airspeed
Wind conditions
Main rotor disk vortex inference (285° to 315°)
Weathercock stability (120° to 240°)
Tail rotor vortex ring state (210° to 330°)
Airspeed 30KIAS or less
Wind direction reported or calculated
Wind speed trigger: set by user
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This animation shows the three wind conditions warning the pilot as the aircraft begins to lose airspeed.