Regulation (EU) No 923/2012
(a) Coordinated Universal Time (UTC) shall be used and shall be expressed in hours and minutes and, when required, seconds of the 24-hour day beginning at midnight.
(b) A time check shall be obtained prior to operating a controlled flight and at such other times during the flight as may be necessary.
(c) Wherever time is utilised in the application of data link communications, it shall be accurate to within 1 second of UTC.
(d) Time in air traffic services
(1) Aerodrome control towers shall, prior to an aircraft taxiing for take-off, provide the pilot with the correct time, unless arrangements have been made for the pilot to obtain it from other sources. Air traffic services units shall, in addition, provide aircraft with the correct time on request. Time checks shall be given at least to the nearest minute.
ED Decision 2013/013/R
TIME IN AIR TRAFFIC SERVICES
In most cases the correct time is obtained through alternative arrangements. The existence of such arrangements should be indicated in the State Aeronautical Information Publication (AIP).