Position (Nav) Lights On Ground
 

Dear PPruners,

I've only recently noticed that most aircraft have their Position (Nav) Lights (NOT Anti Collision) switched on when there is activity (e.g. passenger or crew or service personnel) be it day or night. I would like to know why as my Company does not currently practice this. Is it govern by any authority or just state aviation authority? Any advice would be much appreciated.

As a general rule the position light are on anytime the aircraft is 'power up', that is an APU or GPU is powering the electrical system of the aircraft.

Only when the engines are ready for immediate start are the beacons turned on.

That way when you look at an aircraft on a ramp you can tell it's status with one glance.

thanx con-pilot, is this a Company Policy or common practice?

Our SOP is to use them when necessary e.g. from dusk till dawn.

There's this, this and this to give you food for thought. In the UK, position lights are only required by law during the hours of darkness.

Our company procedure:
Position lights - on ground, aircraft powered
Beacon - engine start, towing or maintenance activity with dangerous activity
Strobe lights - crossing runways and from the moment of runway alignment clearance before takeoff

However, I worked on the Fokker 50, and there it was procedure to never turn on any lights on ground when the engines are not running. Because the lights tend to get hot without the cool airstream around them, and service life went down otherwise.

Thanx everyone for your reply. Much appreciated. I believe its good that the Position Lights ON = Aircraft Manned and should be practised. Hope my Company will soon!

That's exactly how my company operates.