Final answer:
To secure the MD-1 emergency oxygen cylinder pocket during installation, a Square knot is used for its reliability and strength.
Step-by-step explanation:
The type of knot used to secure the MD-1 emergency oxygen cylinder pocket when installing it is a Square knot. A Square knot, also known as a Reef knot, is commonly used for joining two ends of a rope or cord such that they will secure something. The square knot is known for its simplicity and strength when under tension, making it ideal for securing equipment in place. When tying this knot, it's important to ensure that the ends of the rope are of equal length and that the knot is tightened properly to prevent slipping.