123Ships and aircraft
(1)A ship is used for a qualifying purpose at any time when it is let on charter in the course of a trade which consists of or includes operating ships by a person who is—
(a)resident in the United Kingdom or carries on the trade there, and
(b)responsible for navigating and managing the ship throughout the period of the charter and for defraying—
(i)all expenses in connection with the ship throughout that period, or
(ii)substantially all such expenses other than those directly incidental to a particular voyage or to the employment of the ship during that period.
(2)Subsection (1) applies, with the necessary modifications, in relation to aircraft as it applies in relation to ships.
(3)For the purposes of subsection (1)(b) a person is responsible for something if he—
(a)is responsible as principal, or
(b)appoints another person to be responsible in his place.
(4)Subsections (1) and (2) do not apply if the main object, or one of the main objects—
(a)of the letting of the ship or aircraft on charter,
(b)of a series of transactions of which the letting of the ship or aircraft on charter was one, or
(c)of any of the transactions in such a series,
was to obtain a writing-down allowance determined without regard to section 109 (writing-down allowances at 10%) in respect of expenditure incurred by any person on the provision of the ship or aircraft.