When can I descent below the MDA if the approach light system does not have red terminating bars? Specifically, I'm a little confused about Sec 91.175(c)(3)(i) which states:


  The approach light system, except that the pilot may not descend below
  100 feet above the touchdown zone elevation using the approach lights
  as a reference unless the red terminating bars or the red side row
  bars are also distinctly visible and identifiable.


From what I understand, I'm allowed to descend up to 100ft above the touch down zone elevation (TDZE) if I'm able to see and identify the red terminating bars on the approach light systems (ALS).

However, what happens when the ALS does not have the red terminating bars (for e.g. MALSR and MALSF)? Do I maintain my MDA even if I have part of the ALS in sight?
You can descend down to 100ft above TDZE if you have any ALS in sight. You need an ALS with red lights (ALSF I &amp; II) to go below that.

Red terminating bars/red side row bars help you find the threshold. Think of an ALS with red lights as being in the same category as Runway/lights/markings, Threashold/lights/markings, Touchdown Zone/lights/markings, VASI/PAPI, and REIL. Any other type of ALS (MALSR, MALSF, etc.) has the 100ft above TDZE restriction put on it when it is the only thing you can see.

@mins linked to a couple of helpful articles in the comments.