Paragraph 2 Position and size of marks – heavier than air aircraft
The position and size of marks on heavier than air aircraft (excluding kites) must be as specified in this paragraph.
On such aircraft having a fixed wing surface—
the marks must appear on the lower horizontal surface of the wing structure and on the port wing unless they extend across the whole surface of both wings;
so far as is possible the marks must be located equidistant from the leading and trailing edges of the wings;
the tops of the letters must be towards the leading edge of the wing;
the height of the letters must be—
subject to sub-paragraph (ii), at least 50 centimetres;
if the wings are not large enough for the marks to be 50 centimetres in height, marks of the greatest height practicable in the circumstances.
On the fuselage (or equivalent structure) and vertical tail surfaces of such aircraft—
the marks must also appear either—
on each side of the fuselage (or equivalent structure), and must, in the case of fixed wing aircraft be located between the wings and the horizontal tail surface; or
on the vertical tail surfaces;
when located on a single vertical tail surface, the marks must appear on both sides;
when located on multi-vertical tail surfaces, the marks must appear on the outboard sides of the outer-surfaces;
subject to sub-paragraphs (f) and (g), the height of the letters constituting each group of marks must be at least 30 centimetres;
if one of the surfaces authorised for displaying the required marks is large enough for those marks to be 30 centimetres in height (whilst complying with sub-paragraph (g)) and the other is not, marks of 30 centimetres in height must be placed on the largest authorised surface;
if neither authorised surface is large enough for marks of 30 centimetres in height (whilst complying with sub-paragraph (g)), marks of the greatest height practicable in the circumstances must be displayed on the larger of the two authorised surfaces;
marks on the vertical tail surfaces must be such as to leave a margin of at least five centimetres along each side of the vertical tail surface.
On rotary wing aircraft where owing to the structure of the aircraft the greatest height practicable for the marks on the side of the fuselage (or equivalent structure) is less than 30 centimetres—
the marks must also appear on the lower surface of the fuselage as close to the line of symmetry as practicable;
they must be placed with the tops of the letters towards the nose;
the height of the letters constituting each group of marks must be—
subject to sub-paragraph (ii), at least 50 centimetres; or
if the lower surface of the fuselage is not large enough for the marks to be of 50 centimetres in height, marks of the greatest height practicable in the circumstances.
Wherever in this paragraph marks of the greatest height practicable in the circumstances are required, that height must be such as is consistent with compliance with paragraph 4 of this Part.