Sunday, November 20, 2005

ARCAL and AS

There are a whole series of codes that on approach plates and in the CFS to designate aerodrome lighting styles. A pilot briefing an approach when poor visibility is expected will included in the briefing, "and we'll be looking for the AC lighting." Most of the time I go into airports I know already, so I know exactly what the lights will look like, so I don't know the codes all that well. Heck, there are individual airplanes around here that I can recognize in the dark, just by the position, flash frequency, and hue of their anti-collision lighting. But it would be good for me to memorize the codes for the aerodrome lighting types, so I don't have to look them up. I have, in a different area, been surprised by an unexpected set of lights. So today I'll educate myself.

At some aerodromes the pilots have to turn on the lights as we approach. We do this by clicking the microphone with the radio tuned to the same frequency on which we announce our presence to other traffic. A good rule is to turn on the lights when you believe yourself in sight of the aerodrome: the illumination zippering along the runway is a good confirmation that you are lining up for an approach to an aerodrome, and not an old bowling alley. The timer usually keeps the lights on for fifteen minutes, so you key the sequence again as you turn final. For departure, key the lights on before taxi--that tests that your radio is working--and just before starting the takeoff roll.

This pilot activated lighting is called ARCAL, which stands for Aircraft Radio Control of Aerodrome Lighting. We just pronounce it Arr-Kal, rhymes with "bar pal" and we rarely know the correct sequence, so we just click the microphone a whole lot of times to turn it on. This is supposed to be educational, though, so I'll try to come up with a way to remember. To activate Type J ARCAL, click the microphone five times within five seconds. This turns all the lights on for fifteen minutes. To activate Type K ARCAL, click the microphone seven times within five seconds. The trick with Type K is that they are special, like Special K, the breakfast cereal (that's our new mnemonic). If you click the button three more times while the lights are already on, you can turn them down to minimum intensity. Five clicks turns them to medium and seven clicks turns them back to high, and restarts the fifteen minutes of fame.

If the runway is equipped with runway identification lights, bright strobe lights on the corners of the runway, directed towards the pilot landing at that end, then the three click low-intensity setting, extinguishes those lights, called AS.

So that's my lesson for today. Type J ARCAL is the Junior sort that only turns on. Type K is the Special sort that can be turned to different intensities. And AS is the code for the runway identification lights because "as if I want bright strobes in clear weather on short final."

9 comments:

Lord Hutton said...

What if they turn off before you land? That would be a shocker, wouldnt it?

Peter said...

I'm sure here that only ATC can switch on the lights and set their brightness.....

A skill of telling aircraft by their lights is a skill I wish I had..

Anoynmous said...

The airport where my father's Ercoupe was based had incendiary runway lighting. If a pilot planned to be landing there after dark, one made arrangements for someone living nearby to light the smudge pots at the corners of the strip.

Aviatrix said...

"What if they turn off before you land?"

That's why you re-key the sequence on final, to make sure they stay on.

"one made arrangements for someone living nearby to light the smudge pots at the corners of the strip"

That sort of thing is legal in Canada, too.

"A skill of telling aircraft by their lights is a skill I wish I had."

It's not so much a skill as evidence of having been somewhere too long, like being able to recognize your roommates by the sound of their key in the lock. And part of it is of course knowing who is due back at what time.

Traytable said...

Ha, that's weird, in Aus we just call it PAL.

I've heard some great stories from the RFDS (Royal Flying Doctor Service) about some landings to pick up crash victims....

car headlights, 44 gallon drums with fires in, toilet rolls soaked in avgas, if you can make light with it, they've used it!!!

I think there's some guidelines but I figure they have some sort of exemptions, as in the mercy mission rule...

And as far as I remember, PAL here is usually three clicks three seconds apart per click, on the MBZ frequency. Some airports also use PAL out of tower hours, and the ones I've used you could control the apron and taxiway lights also...

Lost Av8r said...

" What if they turn off before you land? That would be a shocker, wouldnt it?"

I believe the lights flash once, two minutes before they will turn off.

Aviatrix said...

Don't count on the flash. From the CFS: "some systems will indicate when the duration period is over by flashing once and then remaining on for a further 2 minutes before extinguishing completely. Other systems offer no indication that the period is ending."

espnapnuts said...

You probably wont be on approach for 15 minutes. Thats an awful lot of time for an approach to a runway. If you are 5 miles out and you cycle the lights you have plenty of time to get down safely. This system works ive used it before and its not too different from most small airports with pilot controlled lights in the states.

Mike friesen said...

Where I fly all the aerdromes have ype k lighting but the dont all work the same. All the vasis dim but the edge lights at some airport dim as well making it very difficult to make out the runway because the vasis are blinding, even on low, 3 clicks. Some runways just the vasis dim and the runway edge lights stay bright. This is much better.