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
Here is the point most often got wrong, and it is worth stating before anything else: the two systems are not on the same clock. Position lights are a duty for the hours of darkness. Anti-collision lights are not. Where they are fitted, the beacon and strobes are required by day as well as by night, in both the European and the American rules, and the reason is obvious once you say it out loud: a flashing light that makes you conspicuous at three miles is worth just as much at noon.
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, 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. But SERA.3215(c) then lifts the anti-collision lights out of that night rule entirely: an aircraft fitted with an anti-collision light system displays those lights also during the day, in flight and on the movement area. And SERA.3215(d) requires an aircraft that is taxiing or being towed with its engines running to show lights indicating that fact, which in practice is the beacon. So in Europe the beacon is not etiquette; it is law.
Under the FAA's 14 CFR 91.209 the split is written into the lettering, and reading past it is the classic mistake:
- 91.209(a) is the night rule. 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.
- 91.209(b) is a separate, standalone prohibition with no time restriction at all: no person may operate an aircraft equipped with an anti-collision light system unless that system is lighted. It bites day and night, subject only to the pilot-in-command's discretion to switch the lights off in the interest of safety.
The FAA's own Aeronautical Information Manual, at 4-3-23, says it in as many words: aircraft equipped with an anti-collision light system are required to operate that light system during all types of operations, day and night.
Note the period in 91.209(a) as well: sunset to sunrise is not the same as the civil-twilight definition the FAA uses for logging night time. The two "night" periods serve different rules, and neither of them governs the anti-collision lights.
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 those legal requirements there is a layer of recommended good practice the FAA Aeronautical Information Manual sets out, and which crews follow the world over. 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.
The one habit that is often filed under airmanship but is not is the beacon with the engine running, turning before start and staying on until shutdown. That is a rule, not a courtesy: SERA.3215(d) puts the engines-running lights on an aircraft taxiing or being towed in Europe, and under 91.209(b) an aircraft equipped with an anti-collision light system has that system lighted whenever it is being operated. The beacon warning bystanders that the aircraft is live is a happy side effect of a requirement, not the reason for it.
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.
- Treating the anti-collision lights as a night-only duty. This is the big one. Position lights are the night rule; the beacon and strobes, where fitted, are required day and night under both 14 CFR 91.209(b) and SERA.3215(c). A daytime departure with the strobes off is not a matter of taste.
- Assuming the lighting period equals the logging-night period. The FAA uses sunset to sunrise for position 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 lights and, with engines running, anti-collision lights apply while manoeuvring on the ground, 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.