OSHA standards require that a qualified rigger be used for any activity related to hoisting, assembly, and disassembly. Qualified riggers must also be used when workers are hooking, guiding a load, unhooking, or connecting a load.
In regards to riggers and signalpersons, "qualified" and "certified" are not synonymous. A crew person can be a certified rigger or signal person without being qualified for all types of loads. OSHA defines a "qualified" rigger or signal person as someone who 1) holds a degree, certificate, or professional standing, 2) has extensive knowledge, experience, and training, and 3) can display their abilities successfully.
Though it is true that a rigger or signalperson does not have to be qualified to handle every crane site job, it is ideal to qualify your entire crew for the reasons below.