# Key Takeaways - To descend below [[DA]]/[[DH]]/[[MDA]], must have three things: 1. Continuously in a position to land with normal rate and normal maneuvers^[This is where a [[VDP]] can help] 2. Sufficient visibility for this [[IAP]]^[For an example of not having this, see [this video](https://youtu.be/XHJx7iJQnfY?si=Pg5WdNkiDpXl95IL)] 3. At least 1 of 12 allowed visual references - The 12 visual references can be grouped as: 1. Other Lights: 1. **[[ALS]]**, but only to [[TDZE]]+100' unless red terminating bars in sight 2. **[[REIL]]** 3. **[[VGSI]]** 2. **Threshold**, threshold markings, or threshold lights 3. **Touchdown zone**, touchdown zone markings, or touchdown zone lights 4. **Runway**, runway markings, or runway lights > [!tip] Sometimes summarized as "Paint, Pavement, and Lights" # Details ## Approach Lighting System The [[ALS]] can be used to descend to [[TDZE]]+100', until the red terminating bars or side row bars are in sight. ![[ALS#^image]] ## Runway End Identifier Lights ![[REIL#^image]] ## Visual Glideslope Indicators ![[VGSI#^image]] ## Threshold, Markings, Lights > [!example] By <a href="//commons.wikimedia.org/wiki/User:Tupungato" title="User:Tupungato">Marek Slusarczyk</a>, <a href="https://creativecommons.org/licenses/by/3.0" title="Creative Commons Attribution 3.0">CC BY 3.0</a>, <a href="https://commons.wikimedia.org/w/index.php?curid=148678841">Link</a> > <a href="https://commons.wikimedia.org/wiki/File:15_Bristol_Airport_sloped_runway_with_runway_lights_in_early_morning_-_Bristol_UK.jpg#/media/File:15_Bristol_Airport_sloped_runway_with_runway_lights_in_early_morning_-_Bristol_UK.jpg"><img src="https://upload.wikimedia.org/wikipedia/commons/1/19/15_Bristol_Airport_sloped_runway_with_runway_lights_in_early_morning_-_Bristol_UK.jpg" alt="15 Bristol Airport sloped runway with runway lights in early morning - Bristol UK.jpg"></a> ## Touchdown Zone, Markings, Lights > [!example] From [[AIM 2]]-3 > ![[Precision Instrument Runway Markings.jpeg]] ![[TDZL#^image]] ## Runway, Markings, Lights > [!example] By <a href="//commons.wikimedia.org/wiki/User:Asurnipal" title="User:Asurnipal">Asurnipal</a> - <span class="int-own-work" lang="en">Own work</span>, <a href="https://creativecommons.org/licenses/by-sa/4.0" title="Creative Commons Attribution-Share Alike 4.0">CC BY-SA 4.0</a>, <a href="https://commons.wikimedia.org/w/index.php?curid=61703632">Link</a> > <a href="https://commons.wikimedia.org/wiki/File:Bettona-Aeroporto_dell%27Umbria_-_Perugia_San_Francesco_d%27Assisi.jpg#/media/File:Bettona-Aeroporto_dell'Umbria_-_Perugia_San_Francesco_d'Assisi.jpg"><img src="https://upload.wikimedia.org/wikipedia/commons/e/e8/Bettona-Aeroporto_dell%27Umbria_-_Perugia_San_Francesco_d%27Assisi.jpg" alt="Bettona-Aeroporto dell'Umbria - Perugia San Francesco d'Assisi.jpg"></a> # Additional Resources - [[FAR 91.175 IFR Takeoff and Landing]] - [[AIM 2]] #concept