Typical example of the intra-TDI phase anomaly observed for device AF7 in row 5 of the Gaia focal plane array during the September 2016 calibration campaign. Sample offsets are plotted as a function of sample start time in the serial scan and have been corrected for all other components (gross prescan level, common baseline, glitch, and flush anomalies). The strong features at 3900 Tmc and 7700 Tmc are observed in many devices with amplitudes that are highest for those nearest the centre of the array, suggesting an electromagnetic pick-up origin.