The Lights That Extend Beyond the Runway-- What Are They Called?


I drive past two sets of them on the way home from work every night, and they fascinate me. When I’m perpendicular to them, the lights on each tower seem to flash almost (almost) simultaneously, but when they pilot approaching the runway sees them, they flash in sequence.

Anyway, do they have an official name besides “runway lights on towers”?

Approach lights

The ones you see flashing are sequential strobes, nicknamed “the rabbit”, pointing directly at the runway and in line with it. They’re most likely the first ones you’ll see in very low visibility conditions, but can be distracting or blinding otherwise, so it’s not uncommon for a pilot to ask the tower to “kill the rabbit”. Other approach lights are on continuously.

Obligatory Elmer Fudd reference.

If one is making an instrument approach (in the clouds), there is a minimum descent altitude (MDA) for each approach. Thou shalt not descend below the MDA unless thou hath the “runway environment” in sight. Those lights are part of the runway environment. Once you see 'em, you can descend below the MDA.

What? So in the movie Die Hard 2, where the terrorists tamper with the radar systems that allow for descent guidance, and kill the runway lights, planes would really not have been able to land?

You missed the point. If you’re on an instrument approach, you can not descend below the minimum-descent-height (aka decision height) unless you can see the runway environment. Lights or no lights, if you can see the runway, then you have the runway environment in sight. But if the weather is foggy and the lights are working, then the runway environment is visible 1/2 mile before you get to the runway itself.

The minimum descent altitude and decision height are not the same thing. A non precision approach has no glide slope and has an MDA. You may not descend below the MDA until visual with the runway, it is a hard floor. A precision approach, such as an ILS, has a decision altitude but no MDA. The decision altitude is the altitude at which you must decide whether you can land or not. Because the decision is made at the DA and you are descending, it is accepted that you will descend below the DA in the process of conducting a missed approach. On some ILS approaches that have a very low DA, you may even touch down on the runway as you go around.

with a CAT -3B system you can pretty much take it to the runway.

OP answer: “Flaming wreckage.”