Originally Posted by
oggers
Because, as S Works explained, his EASA medical restricted him to daytime. He had a piggyback FAA private certificate based on his UK licence and all restrictions on the base licence apply.
Actually S-Works said "He was colourblind and had a specific licence restriction to Day Time Flying ONLY."
Was the restriction on his UK PPL or on his EASA medical? I believe the distinction is important in terms of limitations/restriction that are rolled over to the FAA PPL.