30 CFR § 77.1602
Use of aerial tramways to transport persons.
Persons other than maintenance men shall not ride empty buckets on aerial
tramways unless the following features are provided:
(a) Two independent brakes, each capable of holding the maximum
load.
(b) Direct communication between terminals.
(c) Power drives with emergency power available in case of primary
power failure.
(d) Buckets equipped with positive locks to prevent accidental
tripping or dumping.