A head-on situation at night is deemed to exist when a power-driven vessel sees another power-driven vessel ahead and which lights are visible?

A head-on situation at night is deemed to exist when a power-driven vessel sees another power-driven vessel ahead and which lights are visible?

• A. Only a stern light is visible
• B. No lights visible
• C. Both sidelights and masthead lights visible
• D. Both red and green lights are visible

Answer: (D)

Seeing both red and green navigation lights on another power-driven vessel at night means you’re looking at that vessel’s sidelights. Red on the port side and green on the starboard side are designed to be visible to other vessels from the front and sides. When two power-driven vessels are on reciprocal or nearly reciprocal courses, each will show these sidelights so the other can see them. The simultaneous view of both colors signals a head-on or nearly head-on situation. Because of that, you should act early to avoid collision, typically by steering to starboard to pass port-to-port (often accompanied by reducing speed). Other lighting scenarios indicate different situations: seeing only a stern light would suggest you’re following behind the vessel; no lights visible would imply darkness or poor visibility; seeing sidelights plus a masthead light can occur in various arrangements but the defining sign of a head-on encounter is observing both the red and green sidelights.

Seeing both red and green navigation lights on another power-driven vessel at night means you’re looking at that vessel’s sidelights. Red on the port side and green on the starboard side are designed to be visible to other vessels from the front and sides. When two power-driven vessels are on reciprocal or nearly reciprocal courses, each will show these sidelights so the other can see them. The simultaneous view of both colors signals a head-on or nearly head-on situation.

Because of that, you should act early to avoid collision, typically by steering to starboard to pass port-to-port (often accompanied by reducing speed).

Other lighting scenarios indicate different situations: seeing only a stern light would suggest you’re following behind the vessel; no lights visible would imply darkness or poor visibility; seeing sidelights plus a masthead light can occur in various arrangements but the defining sign of a head-on encounter is observing both the red and green sidelights.