14 CFR §135.161

1. (a)No person may operate an aircraft under VFR over routes that can be navigated by pilotage unless the aircraft is equipped with the two-way radio communication equipment necessary under normal operating conditions to fulfill the following:
   1. (1)Communicate with at least one appropriate station from any point on the route, except in remote locations and areas of mountainous terrain where geographical constraints make such communication impossible.
   2. (2)Communicate with appropriate air traffic control facilities from any point within Class B, Class C, or Class D airspace, or within a Class E surface area designated for an airport in which flights are intended; and
   3. (3)Receive meteorological information from any point en route, except in remote locations and areas of mountainous terrain where geographical constraints make such communication impossible.
2. (b)No person may operate an aircraft at night under VFR over routes that can be navigated by pilotage unless that aircraft is equipped with—
   1. (1)Two-way radio communication equipment necessary under normal operating conditions to fulfill the functions specified in paragraph (a) of this section; and
   2. (2)Navigation equipment suitable for the route to be flown.