The following words or group of words, when used in this section, shall be defined as follows:
Approach-Departure Path. The flight path of the helicopter as it approaches or departs from the emergency helicopter landing facility designated take- off and landing area. The approach-departure path is measured from the edge of the take-off and landing area and is a rising slope determined by a ratio of 8 feet horizontal distance for every 1 foot of vertical height.
Peripheral Area. An obstruction-free (i.e., no intrusions into the approach-departure path) area adjacent to the take-off and landing area serving as a safety zone.
Take-off and Landing Area. The designated area on the emergency helicopter landing facility from which helicopter departures and approaches are intended to originate or terminate.
Touchdown Pad. The load bearing portion of the emergency helicopter landing facility designated take- off and landing area on which a helicopter may land.