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:ok: 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!:hmm:

[Lu Zuckerman]

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.

:E :E

[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]

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!

[chuks]

Position lights on in daytime make me think of that joke bumper sticker that reads, 'If you can read this you are too damn close!' If you can notice whether the position lights are on or off then you are very close indeed to another aircraft! Too close for it to matter much, I fear... but then there are people running around in catering trucks and suchlike, so I guess the lights 'on' option gets my vote.

In our outfit they are to be on per SOP, which relieves us of having to think for ourselves. Back when I used to be able to do that I think I left them off when in bright sunshine to save the bulbs but turned them on otherwise. Now I guess I would leave them on at all times as being a tiny fraction safer.

[Fragman88]

A previous operator I was with had 742/300's and 744's

On the Classic fleet, the lights were left on continuously to avoid thermal shock and `Save the bulbs'.

On the 744, the fleet practice was to turn them off in the daytime to------ you've got it, to `Save the bulbs'!

That's just aviation.

:ok:

[jpsingh]

I think the Australian Rules seem the most appropriate regarding the usage of Position Lights during night and conditions of poor visibility. As far Engineering is concerned, they can also put it on as required basis. Because soon enough someone from stores/ Acounts will come up with the data that by switching off the position lights during day they saved some thousands of Dollars on costs in a year........something akin to United or was it Delta saved $ 40,000 in a year by cutting out on Olives on their drinks !!!! :ok:

[AntiCrash]

A long time ago in a galaxy far away I was ldg. at MYGF in my trusty Twin Commanche. Sometime during the flight I must have turned on the nav lights and didn't catch it. Upon throwing out the gear I did not get the usual little green lights. I went through the checklist pulled back on the throttles, checkall the things you can think of, opened gear extension doors and all,followed up witha tower flyby and then found the @#(&(^ switch for the navlights "on". Autodim to indicator lights rendered the lights too dim to see a difference in the bright Bahamian sun. Best to check out particular airplane's quirks before assuming one way or the other is best.

We used to pull the bezels off the lights in the CV's to check the lights in the daytime. Landing gear up is not a career plus and you'll need 59.5" to taxi.

[Smokie]

Lites on the ground is a good indicator that "Power" is on, on the aircraft. If it is unattended the company engineers will probably investigate and shut it now if it is not due out for a few hours or whatever.

It also Saves the battery!!
As at night or during the day, if lites are still on although the GPU/APU etc are shut down; it is an indication of Power still on, albeit only the battery.

I think that makes sense???

[spannersatcx]

Fragman88, if that was a certain airline from the fragrant harbour, that was because on the 744 it was found that the lense covers were cracking due to the heat from the lamps with them left on 24/7. The lense covers are now made from a different spec material and are less prone to the effects of the heat generated by the lamps and generally don't crack anymore.

If you can't see a wingtip during daylight on the ground turning the pos lights on is'nt going to stop anybody driving into them!!!

[slamer]

I remember traveling through India, being amused at cars turning their lights off at intersections to save on electricity & bulbs. Where I live (not India) Motorcycles and Rental Cars have their lights "hot wired on" all the time. Everytime one of my home light-bulbs "blow" it's when I flick them on, maybe I should leave them going all the time!......whats my point!!..... it depends on your economics what you do.

My Company SOP is for Position lights to be on as an indication the a/c is powered, they remain on regardless, amongst the other things already described, it makes it particuarly easy to pick up a failed bulb on a walk-around, and extremely useful in contrasting and determining relative bearing and direction of other a/c, day and nite. especially on the rwy.
The Atmosphere I Operate in has a constantly changing viz from minute to minute, there is no way I am turning the Position lights on/off as I go into and out-of IMC or other areas of poor viz, "Set it and forget it" overall its gotta be safer.


PS; WHATUNION, Do you mean Cabin lights? have never heard of position lights powered from a "Hot bus" (standing-by to be corrected) therefore the problem is the Bat being left on, not the position lights which by that stage are your only chance to notice the a/c is still powered!

[DFC]

Everyone agrees that the regulations require the lights to be on during night time.

For the regulations, the start and end of night time at the aircraft position is determined at the surface. It also varies from country to country and at times of the year.....one country says 30 min after sunset until 30 min before sunrise, another says sunset to sunrise while yet another uses the first definition during the summer and the second one during the winter.

I have a distant memory of calculating the position of the aircraft at sunrise during a navigation exam but have never used the principle since.

So, for those who leave the lights off by day, when exactly do you turn on the lights and if it is when the sun sets at 35,000ft, isn't this after legal sunset (at the surface)?

Regards,

DFC