Performance standards. The specifications that define the minimum performance and safety standards for certificating parachutes. There are three standards that have been used or are in use: NAS-804, AS-8015A, and AS-8015B.

Permeability. The mass rate of flow or the volume rate of flow per unit projected area of cloth for a prescribed pressure differential. In the U.S., permeability is measured in cubic feet of air through one square foot per minute at ½" of water pressure. Sometimes confused with porosity.

Personnel parachutes. Parachutes designed expressly for human use as opposed to cargo drops or aircraft deceleration.

Piggyback. A single harness, dual parachute system used for intentional parachute jumping where both parachutes are mounted on the back of the jumper.

Pilot chute assist system. A connection of breakcord or Velcro® between the static line and the pilot chute of a sport parachute, which pulls the pilot chute out of the pack and then separates.

Pilot chute. A small parachute used to accelerate deployment; constructed in much the same manner as the main canopy and from similar material. Some types of pilot chutes are equipped with a spring-operated, quick-opening device. The frame is compressed so as to open immediately when released from the pack.

Pin protector flap. A flap that covers the locking pins and cones to prevent the pack from being opened by any means other than the ripcord.

Pleat. A fold sewn in the fabric.

Pocket ripcord handle. Elastic or spring-edged pocket that holds ripcord handle in an accessible position on the harness. The chest-type pocket consists of a piece of straight elastic webbing serving the same purpose.

Porosity. The ratio of void or interstitial area to total area of a cloth expressed in percent. The ratio of open space to covered area of a drag surface. Used for ring slot, ribbon, ring sail, and rotafoil canopies. Not to be confused with permeability.

Premature opening. Any accidental opening of the parachute prior to the intended time.

Prepack inspection. The inspection made on the parachute prior to its packing.

Presser foot. The part of the sewing machine above the feed dog that holds the fabric in place.

Preventative maintenance (PM). The systematic care, servicing, and inspection of equipment and facilities for the purpose of maintaining them in a serviceable condition and detecting and correcting incipient failures. Simple or minor preservation operations and the replacement of small standard parts not involving complex assembly operations.

Proof load. The testing of an item for conformance with strength requirements.

Proper layout. Process by which the canopy and suspension lines are arranged on the packing table for inspection and packing.

Pull the dot. A particular type of snap fastener that can only be opened or closed by pulling in one direction designated by an indented dot on the button.

Pull-up cords. Nylon cords of varying length used to pull up the sides and ends of the container flaps over the container cones and to pull the cones through the grommets. They are also used to pull the suspension lines into place in some types of containers.

Quality control. A method of describing the inspection and test procedures necessary to ensure that each article produced conforms to the type design and is in a condition for safe operation.