Aircraft Headlights,two questions.

[exswissair]

Just wondering why the aircraft industry have'nt started using High Intensity Discharge headlights (HID) on their aircraft like a lot of car manufacturing companies are now starting to?

Just imagine if the 787 had them we could tell from miles away its a 787.

My second question is,why do some QF aircraft have their headlights flashing when coming into land? Is this common practice? Oops that's three questions.

Perhaps AJ can help answer the second one.

[Jerrycobra Boeing]

hids, mabe it has to do with weight or rigulations, iono, and their called landing lights i believe, lol, and the hids would need to be big too

http://en.wikipedia.org/wiki/Aircraft_landing_lights

[v1images]

As the nose wheel lights are only used for taxying I dont think HID lights are of any use, I think they would be too bright, dont forget the lights are useless to the pilots while in the air.

I think some 737's have the 'flashing' lights that drop down from the wings when the landing gear is down, alternating from the left and right. I am sure there was an explanation somewhere but I cannot remember the reason. Possible aircraft recognition? I have also seen it on SWA and AWA 737's.

[Tanner_J]

It's all about safety...pretty sure that's why SWA has them...I thought it was the nose gear lights.

[MCM]

Some QF737's and the Dash 8's under various QF brands have occulting landing lights... They flash to aid aircraft visibility. If you've ever seen one approaching the airport to land, you'll notice you can see the aircraft from a lot further out... they really work!

They're usually on below 10,000ft.

As to why they dont' use that particular type of lamp? To get anything on an aircraft to be different it takes a lot of time and effort to get it approved. Do they have a particulally long life? And are they brighter than the ones that are already used on aircraft? Aircraft landing lights at the moment are not ordinary car headlights!

Aircraft Taxi Lights on the nosegear (on the 744) are a different story... they are not as bright and are designed for use when taxiing around... and to NOT blind other pilots and groundstaff at the airport. If they're too bright, it will destroy other people's night vision.

If the lamps are that good, then maybe one day you'll see them .

[G-DALE]

My second question is,why do some QF aircraft have their headlights flashing when coming into land? Is this common practice?

I believe it's named the 'Pulselight.' They're a common feature on aircraft operating into congested airports to enhance the ability of other traffic spotting you.

Another reason for them is that birds are apparently attracted to landing lights. If in danger most animals (especially birds) try to escape into the direction of the sun. If they can see the sun there can't be an obstacle or enemy inbetween.

If an aircraft has it's landing lights on then the bird would first try to escape in the direction of the 'sun,' until only in the very last moment it might realize that in fact the big bird behind the light also means danger. Hence why the Pulselight is not on steadily, but have a frequency which is changing all the time to prevent from being mixed up with the steadily shining sun.

Perfect example is driving at night with deer/rabbit crossing the road. When You switch to high beam, the deer/rabbit will freeze (so to speak) in the road. However when you dip the headlights and flash them a few times more often than not they'll run away.

Hope that helps.

Dale

[groundpounder]

The CRJ700/900 have HID's for their landing lights, along with Challenger 300's, Citations Mustang's, the A380, and I think Hawker 850's have them as at least an option.

[exswissair]

Some QF737's and the Dash 8's under various QF brands have occulting landing lights... They flash to aid aircraft visibility. If you've ever seen one approaching the airport to land, you'll notice you can see the aircraft from a lot further out... they really work!

They're usually on below 10,000ft.

As to why they dont' use that particular type of lamp? To get anything on an aircraft to be different it takes a lot of time and effort to get it approved. Do they have a particulally long life? And are they brighter than the ones that are already used on aircraft? Aircraft landing lights at the moment are not ordinary car headlights!

Aircraft Taxi Lights on the nosegear (on the 744) are a different story... they are not as bright and are designed for use when taxiing around... and to NOT blind other pilots and groundstaff at the airport. If they're too bright, it will destroy other people's night vision.

If the lamps are that good, then maybe one day you'll see them .

HID lights are supposed to last the life (10-15yr) of the vehicle.They use about 25watts of power as compared to their halogen counterparts 65watts once on.(mind you they need an igniter to start which takes a bit of juice) the heat generated is also less than halogens.

Thanks to all who answered about the flashing landing lights,and letting me know that some aircraft do have HID's