And now for the original legaleze...
The applicable German regulation is the Luftverkehrszulassungsordnung, LuftVZO. Anlage 1 zu § 14 Abs. 1 and § 19 Abs.1 states [my translation]:
3. (1) Aeroplanes, rotary wing aircraft and motorgliders carry the Letter D and the registration on both sides of the fuselage (see pattern 1) or on both sides of the vertical tail (see pattern 6a and 7a). Aeroplanes up to 5.7 t MTOW in addition carry the letter D and the registration on the lower side of the left wing.
[...]
4. (3) The height of the letters must be a minimum of [...]
on the fuselage: 30 cm,
on the wings: 50 cm
On a similar subject:
III. 1. (1.) Aeroplanes, airships, motorgliders and sailplanes carry the federal flag in colour paint on both sides of the empennage if possible in the upper half, rotary wing aircraft on both sides of the fuselage behind the registration markings.
Now take a look at the current Lufthansa livery. See, the flag is not on the empennage. It's on the fuselage. How did they do that?! The LBA issued exemptions to III. 1. (1.) when LH introduced the livery. Not one exemption for the whole fleet, but an individual one for every aircraft when it was re-sprayed...
Out tax Deutschmarks (or Euros) at work...
