Sure, leaving this telescopic boom on the flat deck is easier than unloading it and placing it on firm ground. But anything could go wrong, causing this machine and its load to fall and possibly take out a few windows and people in the process. (WorkSafeVictoria, Australia)
Since it's your first time, you may want to checkout some of the video tutorials.
800-ICW-SAFETY (800.429.7233)
SAFETYOnDemand@icwgroup.com