Basically it is up to the indivual airline. They will have a policy that is officially based on the laws of the country of regristration of the AIRCRAFT.
However that can get confused. Eg Qantas - there is no Australian law setting a minimum drinking age, so it is completely up to the crew as to wether they will serve you alcohol and they have certainly served wine with a meal to my son when he was 14 (SYD
) & 17 SYD
(he always was a big lad).
(Before any other Ozzies jump on me, I said AUSTRALIAN (ie Fedral) law, not state law. State law does NOT apply to aeronautical operations)
Is there a Fedral minimum drinking age in Germany? If not then it is probably basically up to the crew.
BTW he was also served alcohol on UA
when he was 17 too and my two daughters were served wine by JAL when they were 15 & 17, also by AZ
, but that does not count as Italy has no minimum drinking age.
(In case you are wondering, my wife is Italian and she and her kids started drinking (watered) wine around 8 years old, as is the custom in her part of Italy)