Conventions — Ellipsoid: WGS-84 (via proj4js). Local frame: North-East-Down tangent plane at the current position; yaw/pitch/roll are intrinsic Z-Y-X (aerospace) angles, body→NED. ECEF ψ/θ/φ are intrinsic Z-Y-X angles of the same body axes expressed in ECEF, body→ECEF. Moving the position keeps the local attitude pinned and recomputes ψ/θ/φ. Near θ = ±90° (gimbal lock) ψ and φ are not unique.