Exterior lights

[shumway76]

This is the info I got from some instructors with regards to lights usage on light aircraft (which should also apply to large aircraft to some extent, day or night)

1. Anticollision / Beacon - ON when engines are running
2. Nav/Position - ON when aircraft is manned
3. Strobe - ON when entering runway, off upon vacating runway
4. Taxi - ON when taxiing
5. Landing / Takeoff - ON when entering runway, on final approach. OFF upon vacating runway

Pls correct me if I am wrong in any of the above. Also, would greatly appreciate if someone can lead me to official documentation on the usage of these lights.

[thing]

There aren't any really. My club publishes check lists for the particular a/c we have. In none of them does it mention landing lights for take off or landing (This is VFR day). Strobes are usually on at the hold and off after the hold on landing. Beacons on before engine start and off after engine stop although if you only have strobes and no beacons then you don't turn them on.

[Pilot DAR]

If there is a good reason to have any or all lights on, then use what you need. If in doubt, turn them on - unless you're going to blind someone else. Note that most planes equipped with strobes are placarded to turn them off in cloud.

However....

If you own the plane, or would like to be kind to the person who does, don't use lights, particularly landing lights without good reason. Letting alone the comparitively small cost of the bulbs themselves, there is a much more expensive hidden cost in alternator drives.

Assume that the alternator is carrying all of that electrical load. Let's roughly sum it up for a Cessna 12 volt circult: Beacon 7 amps, 3 nav lights, 5.6 amps, strobes 3 amps, landing light 20 amps = 35.6 amps, plus the 1.8 amps of the basic airplane, plus 4 amps for radios, plus maybe you're cautious, and have the pitot heat on 6.5 amps = 47.9 amps. We won't get into the 15 amp flap motor right now...

So you're thinking 60 amp alternator, so no problem carrying that load, and indeed it will, but that is 575 watts, or 3/4 of a HP. Still no problem... but HP is speed (engine RPM) times torque. The alterntor is designed to operate at the torque through it's normal operating RPM, but not at idle, while gliding in to final approach, with everything on. RPM half = torque doubled. If your alternator is belt drive, that's not so bad, you're just working the belt really hard.

However, some Continentals have gear driven alternators, These all contain a flexible drive coupling. That coupling, particularly on 520/550 front mount alternator engines, is an expensive consumable, and it's failure can lead to other even more expensive damage, when it fills the oil system with bits of shredded rubber.

So for the sake of the alternator drive, use less electricity whenever you can. Personally, when I'm landing my 150 at night, I turn off the alternator when I turn final, and use only the battery for the minute or two of the final approach. Back on when I taxi off, and I let the engine coll down a bit above idle, with the lights off, and just monitor the ammeter to see that it is topping off the battery.

It all sounds anal, I know, but I was employed for two months to try to design an improved alternator drive coupling for the 520/550, and could not do better than what was out there, which is only moderately good.

If you need to, light up like a christmas tree, but if you can conserve some electricity, you might be saving more maintenance expence than you thought!

[Mark 1]

The official documentation will depend on the country you're flying in. Hard to tell that from your 'location'.

As a general rule:
No lights are required during daylight, Lots of aircraft don't have electrical systems.
Anti-collision lights, where fitted, should be on when the engine is running or about to be started.
Position lights have little value daytime, but are required when flying or taxying at night.
Landing/taxy lights not usually legally required at night, but obviously help you see/be seen. During the day they aid conspicuity a little, but most beneficial on landing as they make you more visible to aircrafy holding short of the runway.

Your instructor should be able to tell you the local requirements and any additional club procedures.

[shumway76]

Thanks for the info!

Another question :
When starting engines, radio & avionics are switched off. What about lights? There was a school of thought that all electrics (including lights) should be switched off during start. But this is contradicting, considering the fact that beacon light should be on to indicate engine is starting / running. Comments?

[Jan Olieslagers]

That's a compromise. On the one hand you want as little load on the battery as possible, as long as it is not being charged. On the other hand, as you pointed out, it is good to give some visible indication of imminent engine activity.

Make your own compromise: before the first flight of a cold day, you might need every electron the battery has available; but before returning home from a busy fly-in on a hot summer's day, you might prefer to shine every light you have.

FWIW I remember my ground class instructor saying: "There really should be no switch for the rotating beacon, you want it "on" as long as the master switch is."

[IO540]

I don't think anybody can see lights on your plane in daylight, unless they are powerful, and the powerful ones are permitted only as forward facing (landing/taxi lights).

[RTN11]

FWIW I remember my ground class instructor saying: "There really should be no switch for the rotating beacon, you want it "on" as long as the master switch is."

I heard one school had their fleet wired just this way. Another handy product of this was that with just a glance across the line of parked aircraft you could see if someone had accidentally left the master switch on and turn it off before the battery was completely dead.

[Morris542]

I'm not sure there are any official documents for the use of lights for GA.

Personally:

Beacon on just before start up and off after shut down.
Landing lights on/off when entering/vacating the runway.

If I have strobes I try to minimise their usage on the ground, an instructor told me that they have been know to induce epileptic fits for some people apparently.

[Big Pistons Forever]

This is the info I got from some instructors with regards to lights usage on light aircraft (which should also apply to large aircraft to some extent, day or night)

1. Anticollision / Beacon - ON when engines are running
2. Nav/Position - ON when aircraft is manned
3. Strobe - ON when entering runway, off upon vacating runway
4. Taxi - ON when taxiing
5. Landing / Takeoff - ON when entering runway, on final approach. OFF upon vacating runway

Pls correct me if I am wrong in any of the above. Also, would greatly appreciate if someone can lead me to official documentation on the usage of these lights.

There should be a balance between effectiveness and costs in the light aircraft context. By that I mean I feel there is no point in illuminating lights which are unlikely to increase safety, as you are just burning out bulbs for ni good reasons. This is what I teach

1. Anticollision / Beacon - ON before start (warns others that you are about to start)
2. Nav/Position - ON only at night (light aircraft nav lights are too dim to be visible during the day)
3. Strobe - ON when entering runway, off upon vacating runway
4. Taxi light- ON only when taxiing at night (taxi landing lights burn out quickly when used on the ground due to lack of cooling air flow so the extra conspicuity a taxi light provides when taxiing on the ground is not IMO worth the cost of the reduced bulb life)
5. Landing light - ON when entering cleared for takeoff (controlled airport), starting takeoff roll (uncontrolled airport). OFF upon vacating runway

Note: large aircraft use the taxi light to indicate taxi intentions. That is they will turn it on when they are about to start taxing and turn it off if they are stopped and do not intend moving. Therefor if you are operating at an airport with large aircraft operating you can get an idea what the big boys are doing by noting if the taxi light is on or off.