I was in Doncaster a few weeks back , with snow falling and settling on the runway. The 'Ranger' (Airfield Ops) came up to my flight-deck and informed me that the braking action was 'pretty good' as he had just driven along the runway applying his brakes in line with where the main gear would be. I asked what the friction co-efficient was, to which he replied that he hadn't got a reading and it would take 15 minutes for him to get one. I politely asked if he would like to start the process, to which he replied 'well the easyJet has just gone and he was alright'.
