Thursday, December 01, 2005

AE & AF - More Centre Row Lighting

AE lighting is at least 2400' of light bars leading up to the threshold, beginning with white bars, and then with the closest thousand feet being red bars, and then green bars that divide into a V right before the threshold. Fort McMurray has this kind of lighting on runway 25, so I'll remember Fort McMurrAE to remember the code. Unfortunately I don't have a picture of the approach to runway 25 at Fort McMurray at night, so this mnemonic won't work for you.

I have found a picture of type AF lighting, here. As you can see, there are bars running across the white lead in lights every five hundred feet (I'm not certain about the 500'). According to the notes here, at military airports, like Cold Lake, the green threshold lighting wraps around the end of the threshold but I'm tired from looking for pictures of Fort McMurray so I'm not going to find a picture of Cold Lake. AF lighting may or may not include SF lighting in the first 2000'.

The picture of AF lighting also shows PAPI lights, probably P3 for eye-to-wheel height up to 45'. That's the set of four lights you see either side of the runway, partway along the runway. Each light shines red through lower angles and white through higher angles such that if you are on the proper approach slope, you will see two white lights and two red lights, where if you are low you see more red lights and if you are high you see more white lights. In the winter, ice can form on the PAPI lights and act as a lens that refracts the light through the wrong angle, giving erroneous indications. To combat this problem, in the winter the airports are supposed to leave the PAPI lights on all the time to keep them warm, instead of hooking them to the ARCAL, but electricity is expensive, so you can't count on that.

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