Nav lights means aircraft electrically powered?
 

Hi,

I recently heard someone say that leaving the Navigation Lights on after parking the aircraft indicates that the aircraft is electrically powered (by ground power or APU).

Is this a widely acknowledged system? It seems logical to me, but have never heard it before, and cannot find any reference in my company documentation.

Cheers 😆

So if the Nav lights are OFF, does that mean the aircraft is NOT electrical powered? :ugh:

My question is more related to what is the industry norm when securing the aircraft for the night but leaving it electrically powered so the maintenance crew can do their work. Nav lights ON or OFF?

It was a convention that I was taught as a young apprentice. I don't think anything is written down as a policy.

I have worked by it for thirty years. A/C powered, leave the nav lights on.

I was asked by a first officer a few weeks ago, 'Are you a nav lights on or nav lights off man?'.
I said lights on. I imagine the next person he asked said lights off.

Thanks Turin/R T, that is exactly the sort of knowledge/experience I was trying to tap into.

Can I start a little diversion from (OK - hijack) the original thread - and ask about the anti-col light/flashing beacon?

For an aircraft on stand, just what does an illuminated anti-col light signify to you, or what are you trying to tell others when you switch yours on or off?

Anti col on. From an engineer/mechanic's point of view. Means either, engine about to start or are running. Aircraft is about to move, e.g. tow or pushback, or just about any number of other hazardous activity is about to take place such as flaps moving or flight controls functioning.

For me, in any sized-plane, flashing beacon(s) mean "Caution - engine/props - keep away!" Either engine start is imminent, or they are still spooling down. But I wouldn't disagree with Turins "broader" warnings.

I know that on the Boeing flight line, strobes ON mean "engines running" (or imminent engines running).

or just doing a daily lights check! you'll also find all the other external lights on as well.

I'd be intrigued to see nav lights on an aircraft that wasn't electrically powered. How would they work? Candles?

Er, batteries?

The OP made it clear they were referring to an aircraft with APU running or connected to external elextrical power.

Some 747-400's have a Towing Bus. This is powered by the battery. This can power essential items for towing, such as nav lights (not red beacons or white strobes). This can be used when APU or tug power is not available for a tow.

I don't think many people seem to know how to activate it though. It involves selecting the battery ON, Standby Power OFF and a Towing Bus switch on the overhead panel ON.

Might have been in the old days Dave, but many modern Aircraft NAV Lights are powered on the ground by an AC BUS (e.g. Ground Service BUS).

No more flat batteries because Nigel forgot to turn off the lights.

I was taught power on/nav lights on, and I do recall this actually being somewhere on paper at my first airline, but not at the next two.

There is a big difference between GA aircraft which generally have DC nav lights, able to be powered by the battery, and transport category aircraft which have AC nav lights generally not able to be powered by the battery.

GA aircraft are normally electrically unpowered until engine start as you want to save the batteries. Transport aircraft are normally electrically powered the majority of the time even when parked up for some hours, only switching off when being put to bed for the night.

Then there is the tiger moth I used to fly which solved the problem by having no nav lights at all 😆😆😆

Thanks for all the responses... sounds like it is the industry norm, at least to a degree!

Our NAV lights are on 24/7! policy!

Helicopters are different in some respects (including public transport ones).

Red anti-collision lights must be selected on any time the aircraft is running. If they're on, don't approach the aircraft without clearance.

Nav lights will obviously also be on at night if the aircraft is manned. They may or may not be selected on by day.

Most helicopters don't have an APU (there are a few exceptions) and the lights are usually powered by DC from a battery bus., so the lights aren't generally left on if the aircraft isn't manned, to avoid flattening the battery..

Thanks also for the info about anti-col lights.