Airport Landing Lights

May 31, 2004 8:51 AM

Airport landing lights. Anyone care to explain them to me? (more inside)

I'd love to know the significance of landing lights at an airport and the surrounding areas. Specifically, I want to know what the large scale installations several miles out of an airport are for. These are generally red lights, on several columns 100ft+ high, spaced out over 100ft+.

I've driven by a series of these many times but can't figure out what the pilots use them for. They seem too far away from the airport to be part of the infield lighting system. I once thought they could be a visual reference for jetways, but quickly realized that that makes little sense.

Anyways, does anybody know anything about these or have a decent websource to point me to?

posted by smcniven to travel & transportation (13 comments total)

Here is the official government information on Airport lights.

However, if you are seeing red lights several miles away from an airport, they are most likely just indicating obstructions (like cell phone towers, etc...) and aren't part of any navigation scheme.
posted by reverendX at 9:22 AM on May 31, 2004

oh, I just realized you are from canada... there might be some slight differences... any Canadian pilots care to comment?
posted by reverendX at 9:23 AM on May 31, 2004

My guess is that these are approach lights, for use when visibility's not that good. A modern jetliner can do zero-visibility instrument landings, but the airport is designed to safely handle airplanes with less elaborate equipment or equipment failures.

(On preview, what reverendX said.)
posted by hattifattener at 9:26 AM on May 31, 2004

In this day and age, wouldn't it be likely to have landing lights adhere to international standards?
posted by Fupped Duck at 9:29 AM on May 31, 2004

reverendX: Normally I would dismiss them as comm towers etc... but when you drive by them there are about 6-10 towers in a straight line, all identical. In the case of my specific example (Ottawa airport) there is another such strucutre within eyesight of the first one.

Perhaps it's a visual cue to the holding pattern area? or a long range line up to the runway (although like hattifattener indicates most commercial planes would have ILS equipment).

One possible clue/info tidbit: Ottawa's airport is also used by the Armed Forces (mostly Challengers/Airbuses but also Tudors and CF/A-18s from time to time). Perhaps it's a military requirement?
posted by smcniven at 9:34 AM on May 31, 2004

Radio/Communication towers?
posted by BlueTrain at 9:45 AM on May 31, 2004

BlueTrain: don't think so as the lights don't flash as comm towers lights would normally do. No, think of this as a large rectangle reaching into the sky with red lights edges and lines/columns that don't flash.
posted by smcniven at 10:01 AM on May 31, 2004

Is the airport in Ottawa built on a hill? Yeager Airport in Charleston, WV, is built on top of a small mountain, and part of the glideslope for the runway approach is built on tall towers like the ones you describe. (At least, I think it's part of the glideslope. Yeager apparently has a few "issues" and the towers I remember might be part of some other ad hoc system to make the terrain usable as an airfield.)
posted by arco at 10:47 AM on May 31, 2004

I know exactly what smcniven is talking here. Here in Atlanta, there are a lot of those around the airport. Pure speculation, but my guess is a reference point so pilots know where to land. Also could be a reference point for circling patterns, of which there are a lot of at Hartsfield Int'l.
posted by jmd82 at 11:20 AM on May 31, 2004

They are simply visual aids, much the same as the lead lights for bar entrances (not that kind of bar) that boats use to line themselves up with the entrance. If the visibility is poor or it is dark, the pilot may not be able to see the runway, but he can line up with the row of lights and know that he/she is heading in the right direction and can also gauge the start of the runway by where the rows of lights end.
posted by dg at 3:36 PM on May 31, 2004

dg hit it. All I have to add is my father was once an private pilot. He flew a single prop gruman (it was kinda like a flying VW bug.) Anyway the lights helped orientate the pilots perspective to the landing strip. The red and white lights where arranged so that one could judge the altitude of the plane from the arrangement of the lights.

"White over white, just right"

"Red over red, you're dead"

Something like that.
posted by elwoodwiles at 5:42 PM on May 31, 2004

Er, that's red over white, for certain. Dad was talking about VASI lights (Visual Approach Slope Indicator), where white/white means you're above the glidepath, red/white means you're in it, and red/red means you're below it.

There are lots of lighting systems out there, on all different parts of busy runways. The ones that extend off the ends of the runways are approach lighting systems, and generally they convey information about the orientation of the centerline, the distance to the runway threshold, and so forth.

Even though many aircraft are instrumented to land in zero visibility conditions, traditional instrument landings involve a moment at which the pilot looks up from the instruments and verifies that yes, there really is a runway down there, and we're in good shape to land on it. Approach lighting systems can help with these sorts of decisions. (Disclaimer: I'm a mere six hours into my VFR training and can't speak about instrument flying with much authority.)

This quote from a Feb. 1999 AOPA Pilot magazine article lists some of the various approach and runway lighting systems. You can probably google them to see what they look like:

Abbreviations for Airport and Approach Light Systems

ALSF-1 = Approach Lighting System with Sequenced Flashing Lights

ALSF-2 = Approach Lighting System with Sequenced Flashing Lights

MALS = Medium Intensity Approach Lighting System

MALSR = Medium intensity Approach Lighting System w/ Runway alignment indicator lights

ODALS = Omni-Directional Approach Lighting System

SALS = Short Approach Light System

SSALS = Simplified Short Approach Light System

SSALSR = Simplified Short Approach Light System w/ Runway alignment indicator lights

LIRL = Low Intensity Runway Lights

MIRL = Medium Intensity Runway Lights

HIRL = High Intensity Runway Lights

RAIL = Runway Alignment Indicator Lights

REIL = Runway End Identifier Lights

And that excludes experimental lighting systems, which do exist at some airports.
posted by tss at 9:50 PM on May 31, 2004

Yes, there are international standards.
posted by dhartung at 10:34 PM on May 31, 2004