I have some questions about B747-400 landing lights. For instance, why are there four – two inboard and two outboard - and why does each light have its own switch?  

According to the FCOM, only the inboard lights should be switched on before takeoff and before landing. It doesn't mention the outboard lights at all. In practice, I see mostly inboard lights for takeoff and all four lights for landing. Occasionally, though, I see the reverse, all four lights for takeoff and only inboard lights for landing. I should mention  all these instances were in daylight with good visibility.

I have one question about the landing lights on Alaska Airlines B737-990 in the linked video. At 8:56:50, the landing lights appear to be flashing alternately left and right. Why would that be?

I didn't embed the video because it is almost 12 hours long. Does the length matter when embedding?

 

Edited March 30, 20242 yr by charliearon
embed video

Additional landing lights on aircraft that have them are usually pilot's discretion. Landing lights are to be set to on when cleared for takeoff and landing, and depending on the conditions or even just pilot's preference the additonal lights may be switched on at that point as well.

Alaska has pulse landing lights installed on their 737s which are what you see in the video. I guess the idea is to make others more aware of the plane taking off or landing by drawing attention to it thru the pulsating lights.

Embedding the video should not matter!

54 minutes ago, threexgreen said:

Additional landing lights on aircraft that have them are usually pilot's discretion. Landing lights are to be set to on when cleared for takeoff and landing, and depending on the conditions or even just pilot's preference the additonal lights may be switched on at that point as well.

I suppose my main question would be why separate switches for left and right? The A380, for example has two landing lights in each wing root and all four are on a single switch.

54 minutes ago, threexgreen said:

I guess the idea is to make others more aware of the plane taking off or landing by drawing attention to it thru the pulsating lights.

Well, in my case, it worked.

Edited March 30, 20242 yr by dmwalker

8 minutes ago, dmwalker said:

I suppose my main question would be why separate switches for left and right? It seems to be a Boeing feature. The A380, for example has two landing lights in each wing root and all four are on a single switch.

I don't know. Maybe it's to give pilots control over each light in case you want to operate them individually, like when flying through clouds or fog at night and all lights on is too bright, so you can switch some of them off.

I would imagine it's due to electrical connection.  If one switch on a bus fails you'd lose that light essentially.  If all landing lights are on a single switch, you'd lose all landing lights.  The outboard landing lights provide more lateral angled lighting, so it's probably not necessary to use them for landing.  Most operators I've seen online seem to use all of the landing lights for landing however.  It speaks to the nuance of SOPs in each country.  In the US, icing/wing lights are used with landing lights to provide more visibility to other aircraft.  In Europe, the practice in to not use icing/wing lights unless you are actually looking for ice or a wing/engine problem.  I have also heard that some European operators switch off landing lights soon after takeoff, whereas the US practice is on below 10,000.

In regards to the 737 Alaska lights, Alaska, Qantas, and probably some other operators have pulse lights installed for enhanced awareness for birds and other aircraft.  I do think I've seen a Southwest 737 with them in the past.  A good number of business jets have pulse lighting as well.  I don't believe anyone knows if they provide any enhanced safety, they're just an option.

When I was flying the 747 I used to put the inboard landing lights on below 10,000ft and then once I’d received landing clearance I’d also then  put the outboards on as a visual aide memoir I’d been cleared to land.

The landing lights on the 747 are on “low beam” normally , and switch to “full beam” once the wheels are down, they also have a much greater rate of climb than those on the 787 😉