Position Lights in day time

[TE RANGI]

There does not seem to be a consensus as to whether nav/psn lights should be on or off during day time.

I've noticed it's not uncommon that two guys, same airline, same aircraft, adopt different policies. So this may not be stipulated or SOPs not too strictly adhered to.

Hardly a life threatening issue, I know, but just curious about fellow colleagues' views.

[Max Angle]

At bmi we leave them on all the time. Bit silly in my view but at least it saves having to remember to turn them on when it gets dark.

[ferrydude]

normally, the nav lights should be on anytime the aircraft is electrically powered as an indicator, irrespective of day-night .

[TE RANGI]

Thanks for your replies.

The legal requirement ICAO and JAR (and I believe FAR 91 as well) is to have nav/psn lights from SS to SR. In fact MELs usually permit dispatch with them inop in day time.

On my previous airline we were advised to turn them off in daylight/VMC on the 757 (I think they run on expensive inverters). On other types (Douglas) you keep them on all the time and the strobes start flashing when you rotate. On Buses they operate in conjunction with the logo lights.

Many German airlines (LH for one) keep them off during the day, and so do many British aircraft.

Our current SOPs just say "as req'd", so I'd like to know about your company policy.

[GlueBall]

...always ON.

[TopBunk]

Exactly what benefit does leaving them during daylight hours bring? My company subscribes to the 'as required' philosophy, and I turn them off during good viz in daylight hours on the basis that they serve no benefit to flight safety.

However, what I cannot understand in my company is the speed with which people turn off the wx radar. My personal thought is that the radar should be on at all times unless good clear visual conditions prevail, ie on always at night and in imc.

[square leg]

TopBunk, top marks except that when you descend from "VFR on top" into a layer of fog during the approach (thus becoming IMC) there would be no reason to turn the Wx radar ON, as there would be no replies anyway. But I guess you meant this in your statement.

[barberspole]

Is it not indicative of situational awareness whether position lights are required or not?

Airbus position lights are not exactly noticeable in daylight anyway; I think they are used out of habit rather than a conscious need.

[NigelOnDraft]

I often have them "on" in daylight, since I will have selected them on prior to the external check... particularly if the sector or duty period will end up in the dark.

Having turned them "on", I then either forget to turn them off, or don't bother anyway, since having established they work, turning them off then on is the best way to blow the bulbs!

NoD

[HOMER SIMPSONS LOVECHILD]

I remember the head of a large engineering outfit stating that the only reason the bulbs(sorry,"lamps") ever blew was because the bloody pilots kept switching the bloody things on and off all the time.Left them on ever since."Wasting electricity??" Get real!

[Lu Zuckerman]

Night lights are for kids.

I do not know if this applicable to commercial aircraft but on some US Air Force aircraft they had a rash of premature failures on high intensity position lights. The manufacturer investigated and found that the pilots were turning them on during the day. The light was designed to illuminate at a level above the ambient light and when it was turned on during the daylight it burned at maximum intensity resulting in premature failure of the light.

[ShyTorque]

Sun On = Lights OFF

Sun Off = Lights ON

[Dehavillanddriver]

The Australian regulations (CAR1988 195 and beyond) say that the lights must be displayed

(1) At night and in conditions of poor visibility,

Virgin Blue run the lights all the time. It is a reasonable assumption that IMC by day is a condition of low visibility.

[avoman]

A humble engineer here. I like to see position lights on at all times when the aircraft is on the apron and powered. My gut feeling entirely unsupported by any evidence, is that just maybe it might avert a tip or tail collision with those ground vehicles which seem magnetically drawn to collide with aircraft.
A single wingtip repair is worth a lot of bulbs! Furthermore I am the guy who changes your bulbs, and fixes your wingtips! I know which I prefer.
The simplest way is to leave lights on permanently.

[TE RANGI]

Thanks all.

For lack of a common procedure I keep them on at night, in IMC or at any time below 10000', especially for the reason that Avoman so aptly puts. Has anyone considered the ground traffic at MAD?

[whatunion]

To the engineer who leaves them on all the time I would remind him on some a/c you may fall into the trap that one of our engineers did and lead to a cancelled flight, A FLAT BATTERY!

Has anyone asked what value these lights are in flight, great on sailing ships but pretty pointless on jet a/c with strobe anti/colls

[BlueEagle]

whatunion

Think back to your 'Lights' exam, it is the position and relative bearing, (changeable), of the red, green and white position lights that tells you your position relative to the other aircraft and if a risk of collision is a factor or not.
Bright flashing strobes are excellent attention 'getters' but give no other clues.

[whatunion]

can you actually work all that out with a flashing anti coll on. must have been easy in DC 3 days! Prefer to stare at the TCAS!

Any light at a constant bearing gives quite a big clue!

PS probably better if no one thinks back to my lights exam!

[4MONU]

Me thinks that Lights, Radar and Speed Brakes are FREE, and better use them than be sorry.

But lots-a-people prefer to 'save' them for later when they might REALLY want to use them - mostly turns out too late !!

Some new cars now have headlights constantly ON - linked to the ignition.

[keithl]

ShyTorque The Sun may be on a two-position switch where you are, but round here it's on a rheostat!