(b)  
Helicopters shall be designed for landing on water or certified for ditching in accordance the relevant airworthiness code or fitted with emergency flotation equipment when operated in:

(1)  
performance class 1 or 2 on a flight over water in a non-hostile environment at a distance from land corresponding to more than 10 minutes flying time at normal cruise speed;

(2)  
performance class 2, when taking off or landing over water, except in the case of helicopter emergency medical services (HEMS) operations, where for the purpose of minimising exposure, the landing or take-off at a HEMS operating site located in a congested environment is conducted over water; or

(3)  
performance class 3 on a flight over water beyond safe forced landing distance from land.

CAT.IDE.H.325 Headset
Whenever a radio communication and/or radio navigation system is required, the helicopter shall be equipped with a headset with boom microphone or equivalent and a transmit button on the flight controls for each required pilot and/or crew member at his/her assigned station.

CAT.IDE.H.330 Radio communication equipment
(a)  
A helicopter shall be equipped with the radio communication equipment required by applicable airspace requirements.

(b)  
The radio communication equipment shall provide for communication on the aeronautical emergency frequency 121.5 MHz.

CAT.IDE.H.335 Audio selector panel
Helicopters operated under IFR shall be equipped with an audio selector panel operable from each required flight crew member station.

CAT.IDE.H.340 Radio equipment for operations under VFR over routes navigated by reference to visual landmarks
Helicopters operated under VFR over routes that can be navigated by reference to visual landmarks shall be equipped with radio communication equipment necessary under normal radio propagation conditions to fulfil the following:
(a)  
communicate with appropriate ground stations;

(b)  
communicate with appropriate ATC stations from any point in controlled airspace within which flights are intended; and

(c)  
receive meteorological information.

CAT.IDE.H.345 Communication and navigation equipment for operations under IFR or under VFR over routes not navigated by reference to visual landmarks
(a)  
Helicopters operated under IFR or under VFR over routes that cannot be navigated by reference to visual landmarks shall be equipped with radio communication and navigation equipment in accordance with the applicable airspace requirements.

(b)  
Radio communication equipment shall include at least two independent radio communication systems necessary under normal operating conditions to communicate with an appropriate ground station from any point on the route, including diversions.