IWC Big Pilot’S Watch Perpetual Calendar Watch, 46.2mm Blue Dial, IW503605The Big Pilots Watch Perpetual Calendar in stainless steel with a blue dial continues the long standing tradition of perpetual calendar watches in the Big Pilots collection. No other complication has taken centre stage on the dial of the Big Pilots Watch more often than the perpetual calendar. Developed during the 1980s by IWCs former head watchmaker Kurt Klaus, the large dial not only lends itself well to the mechanisms many display, but it also