B737 Fire Warning and Master Caution Lights

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Master Fire Warning (FIRE WARN) Lights

  • Illuminated (red) – indicates a fire warning (or system test) in one or more of the following:
    • engine
    • APU
    • main wheel well
    • cargo
  • Associated aural alarms include:
    • fire warning bell
    • if on ground, remote APU fire warning horn.
  • Push – extinguishes both master FIRE WARN lights
    • silences fire warning bell
    • silences remote APU fire warning horn
    • resets system for additional warnings.
  • Note: Pushing fire warning bell cutout switch on overheat/fire protection panel results in the same actions.

MASTER CAUTION Lights

  • Illuminated (amber) – a system annunciator light has illuminated.
  • Push – extinguishes both MASTER CAUTION lights
    • system annunciator light(s) extinguish
    • resets system for additional master caution conditions.

System Annunciator Panel

  • Illuminated (amber) – an amber light, relating to illuminated system annunciator, has illuminated on forward overhead, aft overhead or overheat/fire protection panel.
  • To extinguish – push either MASTER CAUTION light.
  • To recall – push and release either system annunciator panel
    • if a master caution condition exists, appropriate system annunciator(s) and MASTER CAUTION lights illuminate
    • a single fault in certain redundant systems, or some simple faults, cause the system annunciator light to illuminate during a recall. The system annunciator light will extinguish when the MASTER CAUTION light is pushed.