91.175 (c) are RW edge lights = "runway

[flyboy321]

In part 91.175 (c) it says you can use "runway lights" to decend below MDA (DH)....So, what EXACTLY constitutes "runway lights" (i.e. runway edge lights, centerline lights, etc...)?
- Please refrence.....

Thanks

 

[tarp]

This must be some airline interview question for somebody who is hiring......

The best answer is "nobody knows".

It's one of the beautiful things about the law and regulations - every once in a while there's a hitch. Open to interpretation, use pilot judgement, etc, etc.

The common law, IMHO, is that the framers meant to say Runway Edge lights. i.e. that you can determine its a runway by seeing the field of lights such that you see BOTH edges of the runway.

CL's (centerline lights) by themselves are worthless. They do not describe a "box" of lights. They are a string of lights. One string does not a runway make. Same goes if you can only see one string (or side) of the runway edge lights. Are you going to descend into the leftside only lights? Are these the left side lights or the parallel interstate next to the airport?

The reason interviewers ask questions like these is to see how you are thinking.

I was working with an Instrument student the other day and we were talking about this rule. I thought back over my nearly 30 yrs in aviation and realized I've shot about 12 approaches to real minimums and used the "lights" call about 2 of those. At 200ft above terra firma, my self preservation mode has me pushing those throttles/TL's forward - only a compelling view of something very recognizable as a runway is going to make me go down further.

So now go back to the question. I'm in V-V001 conditions, I'm 100ft above the ground because I did see the Approach light field, moving forward I see one-half the runway as defined by that I can see 3 CL's and 2 RE lights on the right side? Do I land? Have I seen enough to comfortably put the bird down or do I bug out since I don't have the left edge lights?