10. For the purposes of this Part—
(a)‘visual flight conditions’ means weather conditions such that the pilot is able to fly by visual reference to objects outside the aircraft;
(b)‘instrument flight conditions’ means weather conditions such that the pilot is unable to fly by visual reference to objects outside the aircraft;
(c)‘relevant period’ means a period which immediately precedes the commencement of the flight, being, subject to paragraph 6, a period—
(i)in the case of paragraph 2(8), of three months;
(ii)in the case of paragraphs 2(1)(b), 2(5)(b), 2(6)(b), 2(7)(b) and 3(1)(b), of six months; and
(iii)in the case of paragraphs 1, 2(1)(a), 2(5)(a), 2(7)(a), 3(1)(a), 4 and 5(1), of 13 months.