Expect some amount of time related disruption around April 7 00:00 GPS as the GPS 1K week cycle rolls over and GPS receivers that have not been patched or updated to use new CNAV and MNAV messages, or compensate for not doing so, provide incorrect time, position, and navigation solutions. Garmin, for example, rolled out updated firmware for some of their receivers, including the 18x popular on NTP servers, just over a week ago. Previous rollovers have shown symptoms of clocks being out by multiples of 256 weeks, some resetting to the GPS epoch at 1980 Jan 06 Sun 00:00:00+0000, showing misleading position and navigation solutions, depending on what inputs are used to solve the 4D simultaneous equations. Airlines, ships, and well maintained commercial trucks shouldn't crash, but the rest of us should check any devices using GPS! If my script is correct, the rollover occurs at the indicated instant on the time scales below: 2019 Apr 06 Sat 23:59:42+0000 JD 2458580.499792 MJD 58579.999792 ToD 86382 NTP 3763583982 Unix 1554595182 GPS We 2048 Cy 2 Wn 0 Wa 0 ToW 0 DoW 0 ToD 0 TAI-UTC 37 TAI-GPS 19 GPS-UTC 18 [*NOT* an April Fools post, unfortunately!] -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada This email may be disturbing to some readers as it contains too much technical detail. Reader discretion is advised.