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How Flying Works

What the Red, Green and White Lights on a Plane Mean

In July 1848 the British Admiralty told every sea-going steam ship to carry three lights at night: a white one at the masthead, a green one on the right-hand (starboard) side and a red one on the left-hand (port) side. Steam had made ships fast enough to meet in the dark before anyone could see a hull. The colours fixed that. Glimpse a red light and a green one, and you know which way the other vessel is heading.

Look up at an airliner at night and you’ll see the same rule, nearly 180 years on. Red on the left wingtip, green on the right, white at the back. It’s the oldest part of aircraft lighting, and it still does the most important job: telling everyone else which way you’re pointing.

The three position lights, and their exact angles

The steady red, green and white lights are called position lights (pilots often say “nav lights”). Their layout isn’t left to taste. US certification rules for airliners (14 CFR 25.1385 and 25.1387) say the red light goes on the left and the green on the right, as far apart as practical, and that each must shine across a fixed slice of the sky.

That slice is called a dihedral angle, which here just means a wedge of space measured around the aircraft. The red light covers the 110 degrees from dead ahead round to the left. The green covers 110 degrees to the right. The white light at the tail covers the 140 degrees left over behind. Add them up and you get 360: from any direction, you see at least one colour.

Interactive · position lights

Move around the aircraft: which lights can you see?

RED 110°GREEN 110°WHITE 140°YOU

You see

GREEN

Green only: you’re off its right side. It’s crossing from your left to your right.

Flight phase (typical airline practice)

  • Position (nav) lights ONSteady red left, green right, white tail. Show other pilots which way you’re pointing.
  • Beacon ONFlashing red, top and bottom of the fuselage. On before engine start: “stay clear, engines live.”
  • Strobes ONVery bright white flashes at the wingtips and tail. Usually on from entering the runway.
  • Landing lights ONPowerful forward lights to see the runway and be seen on approach.
  • Taxi light OFFNose-gear light that lights up the taxiway ahead.
  • Logo lights ONLight up the tail livery. Makes the aircraft easier to spot near busy airports.

Exact switch timing varies by airline procedure and airport. Pilots can switch strobes off in cloud if the flashes become distracting.

Reading another aircraft’s lights

This is the point of the whole system. Picture another aircraft in the dark. If you see red on your right and green on your left, its left wing is on your right, so it’s facing you. If you see only green, you’re off its right side and it’s crossing in front of you from left to right. Only a white light means you’re behind it and it’s going away.

Pilots don’t rely on this alone today. Radar, air traffic control and collision-avoidance systems do most of the work. But the lights cost almost nothing and never stop working when a screen does.

The wingtip of a Boeing 737-800
A Boeing 737-800 wingtip. The tip fairing is where the position light and the white strobe live. Photo: Wikimedia Commons (author and licence on the file page).

The flashing ones: beacon and strobes

Steady lights tell you direction. Flashing lights tell you something else: “I’m here, and I’m active.” These are the anti-collision lights, and there are two kinds.

The beacon is the flashing red light on the top and bottom of the fuselage. Crews turn it on just before starting an engine and leave it on until the engines are shut down after parking. For ground staff that’s the signal: engines live, stay clear of the intakes and exhaust.

The strobes are the brilliant white flashes at the wingtips and usually the tail. Most airlines switch them on as they enter the runway and off once they’ve cleared it after landing. They’re bright enough to dazzle people working nearby on the ground, which is why they stay off while taxiing.

US operating rules (14 CFR 91.209) require position lights from sunset to sunrise, and anti-collision lights whenever the aircraft is fitted with them, day or night. There’s one exception: the captain can switch them off if that’s safer, for example in thick cloud, where the flashes bounce back into the cockpit and become distracting.

Lights for seeing, not just being seen

  • Landing lights are the big forward-facing lights on the wings or under the fuselage. They light up the runway on approach and make the aircraft obvious to everyone else around the airport.
  • Taxi lights, usually on the nose landing gear, light the taxiway straight ahead.
  • Runway turnoff lights point out to the sides, so the crew can see the exit while turning off the runway.
  • Wing inspection lights shine from the fuselage onto the front edge of the wing, so the crew can check for ice at night.
  • Logo lights sit on the horizontal tail and light up the airline’s tail fin. They show off the livery, and they make the aircraft easier to spot on a crowded apron.
View from an Airbus A320 cockpit during a night landing, with the runway lights ahead
The view from an Airbus A320 cockpit during a night landing. The aircraft’s own landing lights help light the runway ahead. Photo: Wikimedia Commons (author and licence on the file page).

Why the cabin lights dim for landing

One more light you’ll notice from your seat: the cabin goes dim for night takeoffs and landings. That’s so your eyes are already adjusted to the dark. If an evacuation were ever needed, you’d see the floor path lighting and the outside straight away, instead of stepping blind from a bright cabin into the night.

Sources & Further Reading

Common Questions

Frequently Asked Questions

Why is the red light on the left wing and green on the right?

Aviation copied the rule ships already used. Since the British Admiralty’s 1848 regulations, steam ships have shown red on the left (port) side and green on the right (starboard). Aircraft use the same layout, so anyone who sees the lights can tell which way the aircraft is pointing.

What does the flashing red light on a plane mean?

It’s the beacon, an anti-collision light on the top and bottom of the fuselage. Crews switch it on just before an engine starts and leave it on until the engines are shut down, so ground staff know the aircraft is live and to keep clear.

Why do planes flash bright white lights?

Those are the strobes, at the wingtips and usually the tail. They make the aircraft stand out to other pilots. Most airlines switch them on when entering the runway and off after landing, because they can dazzle people nearby on the ground.

Why do planes keep their lights on during the day?

Because being seen matters in daylight too. US rules (14 CFR 91.209) require an aircraft’s anti-collision lights to be on whenever it has them, day or night, unless the captain decides switching them off is safer, for example in cloud where the flashes reflect back.

If I see red on the right and green on the left, what does that mean?

The aircraft is pointing towards you. Its left wing (red) is on your right as you face it. If you see only a steady white light, you’re looking at its tail and it’s moving away.

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Last reviewed: October 2026. Facts that change, such as fleets, airspace and airline ownership, are re-checked on a schedule. Spotted an error? Email contact@skyplus.news and we’ll fix it. See how we check facts.