Aircraft lights do two jobs at once: they let other pilots see you, and they let you read which way another aircraft is heading in the dark. Both rely on a simple colour code that has not changed in a century, and on a clear rule about when the lights have to be on.
This is general educational information, not operational, legal, or regulatory advice. Rules differ by authority and change over time. Always verify against current official sources and follow your operator's approved procedures.
The two kinds of light
An aircraft carries two distinct lighting systems, and it helps to keep them separate.
Navigation lights, also called position lights, mark the aircraft's shape and orientation with a fixed colour code: red on the left (port) wingtip, green on the right (starboard) wingtip, and a white light shown to the rear. They are steady, not flashing, and the colours are deliberate, because they tell another pilot which way you are pointing. The same red-left, green-right convention is shared by ships, which is where aviation borrowed it.
Anti-collision lights are the attention-grabbers: the flashing red rotating beacon and the bright white strobes. Their job is not to show orientation but to make the aircraft conspicuous from a long way off, in the air and on the ground. They flash precisely so the eye catches them.
The two systems answer different needs. The steady navigation lights say which way I face; the flashing anti-collision lights say here I am.
Reading another aircraft's lights
Because the colours are fixed, the navigation lights let you judge another aircraft's aspect, the direction it is pointing relative to you, at a glance:
- If you can see both its red and green wingtip lights, you are looking at its front, so it is pointing roughly towards you. That is the configuration to treat with most caution, because a head-on closure gives you the least time.
- If you see only its white tail light, you are behind it, overtaking from the rear.
- A single red or a single green tells you it is crossing, and which way, with the colour on the wingtip nearest you.
This reading dovetails with the right-of-way rules. The overtaking position is defined by the angle from the tail at which, at night, you would see neither of the other aircraft's wingtip lights, only its rear light, which is exactly the geometry in which you, as the overtaking aircraft, must give way and alter to the right.
When the lights must be shown
The headline rule is the same on both sides of the Atlantic: the lights come on for the hours of darkness. The detail of how the period is defined differs slightly.
Under SERA.3215, by night all aircraft in flight display navigation lights and anti-collision lights, and no other lights that might be mistaken for them. Aircraft moving on the manoeuvring area show position lights and, if their engines are running, anti-collision lights, with lights to mark their extremities where these are not otherwise shown. The "night" period is the one defined by the authority, typically the hours between the end of evening civil twilight and the beginning of morning civil twilight.
Under the FAA's 14 CFR 91.209, no person may operate an aircraft from sunset to sunrise without lighted position lights, nor park or move it in a night flight operations area without lights or a marked position, and an aircraft equipped with an anti-collision light system must operate those lights. Note the period: 91.209 uses sunset to sunrise for showing lights, which is not the same as the civil-twilight definition the FAA uses for logging night time. The two "night" periods serve different rules.
Turning the anti-collision lights off
There is a sensible exception built into both systems. Bright strobes reflecting back off cloud or haze at night can dazzle the crew and destroy night vision, so the anti-collision lights may be switched off when they do more harm than good. SERA.3215 allows it where the lights would adversely affect the satisfactory performance of duties or subject an outside observer to harmful dazzle. The FAA's 91.209 lets the pilot-in-command turn them off whenever it is in the interest of safety. The navigation lights, by contrast, stay on through the hours of darkness; it is the flashing lights that may be paused when conditions warrant.
Landing, taxi and other lights
Navigation and anti-collision lights are the two systems the rules of the air name, but an aircraft carries more. Landing lights throw a powerful beam forward for the approach and landing; taxi lights light the ground ahead at slower speed; and larger aircraft add logo lights, wing-inspection lights and runway-turnoff lights. None of these is a position light, so none tells another pilot which way you face, but they are intensely useful for one thing: conspicuity. A landing light pointed roughly at conflicting traffic makes a small aircraft visible far sooner than its navigation lights alone, by day as well as by night, which is why the beam is used well beyond the landing itself.
Conventions for using the lights
On top of the legal requirement to show navigation and anti-collision lights at night, there is a layer of recommended good practice the FAA Aeronautical Information Manual sets out, and which crews follow the world over. The anti-collision lights, the beacon especially, go on whenever the engine is running, so the beacon doubles as a warning that the aircraft is live, turning before start and staying on until shutdown. Exterior lights, including the landing light, go on when entering or crossing a runway, a simple habit that has cut runway incursions. And the "operation lights on" idea encourages turning the landing light on in the high-traffic environment below about 10,000 ft and near an aerodrome, day or night, purely to be seen.
These conventions are about conspicuity rather than orientation, so they complement the colour code rather than replace it. The steady red, green and white still tell another pilot which way you are pointing; the bright forward beams and flashing strobes simply make sure the other pilot looks in your direction in the first place. Used together, they answer both questions a converging pilot needs answered at night: where you are, and which way you are going.
A worked example
You are flying a night cross-country with your navigation lights steady and your strobes flashing. Ahead and slightly above, you pick up a single steady white light that is not moving much against the background. Because you can see only the white light and neither a red nor a green wingtip, you are looking at the rear of another aircraft: you are overtaking it. The right-of-way rules make you the give-way aircraft, so you alter to the right and keep clear until you are entirely past.
Later, climbing into a layer of thin cloud, your strobes begin flashing back at you off the moisture, washing out your view forward. You exercise the exception: under 91.209, or SERA.3215 in European airspace, you switch the anti-collision strobes off while in the cloud to protect your night vision, leaving the navigation lights on, and turn the strobes back on when you are clear. The aircraft stayed lit for others throughout; you simply paused the lights that were blinding you.
Common pitfalls
- Mixing up the colours. Red is left, green is right, white is aft. Reverse them and you will read another aircraft's aspect backwards.
- Confusing the two systems. Navigation lights show orientation and stay on; anti-collision lights make you conspicuous and may be paused.
- Assuming the lighting period equals the logging-night period. The FAA uses sunset to sunrise for lights but civil twilight for logging night, so they are different windows.
- Leaving strobes on in cloud at night. They can dazzle you; the rules let you switch the anti-collision lights off when they affect the crew or observers.
- Forgetting ground lighting. Position and, with engines running, anti-collision lights apply while manoeuvring on the ground at night, not only airborne.
In Pilot EFB
Pilot EFB is a study and planning companion for the rules of the air, sitting alongside your night-flying notes and the rest of your offline-first briefing. It does not control your lights, sense darkness, or tell you when to switch the strobes on or off, and the binding requirements are those in the current rule for your airspace and operation. Pilot EFB is not a certified Electronic Flight Bag, so treat it as a study and planning aid and fly the lighting rules from your official source of record.