Scale E
(i) (a) In the case of a helicopter or gyroplane, a slip indicator.
(b)In the case of any other flying machine, a slip indicator and either a turn indicator or, at the option of the operator, an additional gyroscopic bank and pitch indicator.
(ii) a gyroscopic bank and pitch indicator;
(iii) a gyroscopic direction indicator;
(iv) a sensitive pressure altimeter adjustable for any sea level barometric pressure which the weather report or forecasts available to the commander of the aircraft indicate is likely to be encountered during the intended flight.