In the SCBA head-up display readings, how many green lights indicate 100% to 75% air supply?

In the SCBA head-up display readings, how many green lights indicate 100% to 75% air supply?

• A. One green light (75-100%)
• B. Four green lights (100-75%)
• C. Two yellow lights (36-49%)
• D. One red light (under 35%) and alarm

Answer: (B)

In an SCBA head-up display, a small set of lights shows how much air you have left. Green lights mean you’re in a safe range, yellow means caution, and red signals danger. When you see four green lights lit, that corresponds to the air being between 100% and 75% remaining, so you still have plenty of air. As the percentage drops, the lights change to reflect lower levels—two yellow lights indicate about 36% to 49% remaining, and a red light with an alarm appears when air is under 35% to warn of imminent risk and prompt exit or bailout. So four green lights specifically indicate 100% to 75% air.

In an SCBA head-up display, a small set of lights shows how much air you have left. Green lights mean you’re in a safe range, yellow means caution, and red signals danger. When you see four green lights lit, that corresponds to the air being between 100% and 75% remaining, so you still have plenty of air. As the percentage drops, the lights change to reflect lower levels—two yellow lights indicate about 36% to 49% remaining, and a red light with an alarm appears when air is under 35% to warn of imminent risk and prompt exit or bailout. So four green lights specifically indicate 100% to 75% air.