737-800 new engines being 'run in'?
Was recently on a jet2 flight out of LBA, in one of the shiny new 737s. The captain said during taxi, that 'manufacturers advice recommends that during takeoff in cold weather operation, they line up, increase power slightly (around 40% from what I could tell) and wait for about 20 seconds, before coming off the brakes going through to takeoff thrust. The runway was big enough and the flight wasn't full and it was also a cold day, so no apparent requirement for TOGA.
Been trying to get my head round why this is but getting nowhere. Any ideas?