Concerns raised about cascaded Kalman filters for loose coupling and/or usage of input data “massaged” in unknown ways are not new, but are routinely excused by requirements to use coordinates from receivers not providing measurement outputs. Often, however, a receiver’s internal 8-state extended Kalman filter (EKF) is not fed with precise carrier phase data — and even when it is, its velocity outputs (being both filtered and unaided) have limited ability to follow high dynamics. Velocity pseudomeasurements under those conditions interfere with IMU aiding.