Hi Andrew, At Toronto Pearson we don’t have people on call for fire investigations. When an investigator is needed the CFPO gets a call from the on duty Platoon Chief and then the CFPO contacts the Area FPO. If an FPO is not available another FPO is called to attend. The clock starts when they receive the call OT@ 1.5hrs and OT@ X 2 if they go beyond their normal 9.4hrs during that week. If no FPOs are available the CFPO or Platoon Chief will perform the investigation. Thanks, Frank