OK, strike the iterative part of accelerometer calibration for the moment. At the start, the quad-frame error vectors (QFEV) look fit-for-purpose, and the intention was that during the course of a flight they would converge towards increasingly better error vectors. But rather than converging to the ‘right’ value over time, they are diverging rapidly. For the moment, I’ll have a go just using the initial values and see what happens.
The divergence does seem rather OTT, suggesting a possible bug in the code, so the hunt is on.