Do You Know Your Regulations?
Under the Work at Height Regulations 2005 (UK) (or equivalent in other jurisdictions), employers must plan for emergencies and rescue, and must not rely solely on emergency services like the fire brigade.
Regulation 4(4): "Every employer shall ensure that work at height is properly planned, appropriately supervised, and carried out in a manner which is so far as is reasonably practicable safe."
Regulation 4(5): "Planning includes planning for emergencies and rescue."
Why not the fire brigade?
They are not guaranteed to be available immediately.
Response times vary – a person suspended in a harness (e.g., in a fall arrest scenario) can lose consciousness or suffer suspension trauma within minutes.
Firefighters are trained for general rescue, but not specifically for your equipment or layout.