The incident class indicates the level of distress indicated by a SAR incident:

• M1 - Immediate Danger
  There was grave and immediate danger to persons (vessel on fire/sunk, persons in the water etc...)
• M2 - Potential Danger
  A situation existed that could lead to a state of immediate danger (vessel drifting toward shore, taking on water but pumps keeping up etc...)
• M3 - No Danger
  No danger but still requiring assistance (vessel broken down, lost etc...)
• M4 - False Alarm or Hoax
  No assistance was necessary - call was due to a mistaken belief or a hoax

Do not confuse incident Class with incident Type - the class is a general clasification whereas the type attempts to specify the specific type of incident.