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PAPI (Precision Approach Path Indicator)	Provide visual guidance for pilots during landing. It consists of four lights that display either red or white, indicating whether the aircraft is too high, too low, or on the correct glide slope for landing.
Parasitic Drag	Parasitic drag is a form of aerodynamic resistance that occurs when air interacts with an aircraft's surface. It includes form drag, skin friction, and interference drag, increasing fuel consumption and reducing efficiency. Designers minimize parasitic drag through streamlined shapes, smooth surfaces, and retractable landing gear.
Payload	Payload refers to the total weight of passengers, cargo, and baggage that an aircraft can carry, excluding fuel and the aircraft’s own weight. Airlines optimize payload capacity to maximize profitability while ensuring the aircraft remains within safe operational limits.
Phugoid Oscillation	A phugoid oscillation is a long-period flight dynamic motion where an aircraft alternates between climbing and descending without significant changes in angle of attack. These oscillations are caused by a balance between kinetic and potential energy, and pilots often correct them with slight pitch adjustments.
Pitot Tube	A pitot tube is a crucial airspeed measurement device on an aircraft. It measures dynamic pressure from the oncoming airflow, converting it into airspeed readings for pilots. The tube must be heated in cold conditions to prevent ice blockages that could lead to erroneous readings.
Pitch Angle	Pitch angle refers to the angle between an aircraft’s nose and the horizon. Positive pitch angles indicate an upward climb, while negative pitch angles represent descent. Proper pitch control is essential for takeoff, cruising, and landing maneuvers.
Pilot in Command (PIC)	The Pilot in Command is the individual legally responsible for the safe operation of an aircraft during a flight. The PIC has the final authority over all flight decisions, ensuring adherence to aviation regulations and responding to any in-flight emergencies.
Pilot-Induced Oscillation (PIO)	PIO occurs when a pilot unintentionally amplifies control inputs, causing the aircraft to oscillate. It can result from overcorrections or delays in response. Advanced fly-by-wire systems and pilot training help mitigate the risks associated with PIO.
Pilot Weather Report (PIREP)	A PIREP is a real-time weather report submitted by pilots in-flight. It provides information on turbulence, icing, and visibility conditions, helping other pilots and meteorologists refine forecasts.
Pilot's Operating Handbook (POH)	The POH is a manual provided by aircraft manufacturers detailing operational procedures, performance data, emergency procedures, and weight/balance information. It serves as a crucial reference for pilots.
Piston Engine	A piston engine, also known as a reciprocating engine, is commonly found in general aviation aircraft. It converts fuel combustion into mechanical motion using pistons and crankshafts. Piston engines are widely used in small propeller-driven planes due to their reliability and efficiency at lower altitudes.
Pitot-Static System	The pitot-static system provides airspeed, altitude, and vertical speed data to an aircraft’s instruments. It consists of pitot tubes and static ports, both of which must remain unobstructed for accurate readings.
Plenum Chamber	A plenum chamber is an enclosed space in an aircraft engine designed to evenly distribute airflow to the intake manifold or combustion chamber. It helps maintain consistent pressure, improving engine performance and fuel efficiency.
Power-Off Stall	A power-off stall occurs when an aircraft stalls during a glide or landing approach with reduced engine power. Pilots train in power-off stalls to practice recovery techniques for real-world scenarios.
Power-On Stall	A power-on stall occurs when an aircraft stalls with the engine at high power, typically during takeoff or climb. Recognizing and recovering from power-on stalls is a key part of pilot training.
Preflight Inspection	A preflight inspection is a thorough check performed by pilots before every flight. It includes examining the aircraft's structure, controls, fuel, and instruments to ensure airworthiness and safety compliance.
Pressure Vessel (Aircraft Cabin)	A pressure vessel is the sealed portion of an aircraft designed to maintain cabin pressure at high altitudes. It protects passengers and crew from the effects of low atmospheric pressure.
Primary Flight Display (PFD)	The PFD is an advanced digital screen in modern aircraft cockpits that combines crucial flight data, including attitude, altitude, airspeed, and heading, into a single interface. It enhances situational awareness and reduces pilot workload.
Propeller Blade Angle	The propeller blade angle determines the amount of thrust generated by a propeller. Adjustable-pitch propellers allow pilots to optimize efficiency for different flight phases, such as takeoff, cruising, and landing.
Propeller Governor	A propeller governor automatically adjusts the propeller blade pitch to maintain a set RPM. It ensures optimal performance by balancing thrust output with engine power demands.
Propeller Overspeed	Propeller overspeed occurs when the propeller RPM exceeds safe operating limits, potentially causing structural damage to the engine or propeller. Governors and engine controls prevent excessive speeds by regulating pitch.
Prohibited Airspace	Prohibited airspace is a restricted area where civilian aircraft are not allowed to enter due to security, military operations, or government restrictions. Violations can result in interception by military aircraft.
Propellant	Propellant refers to the fuel and oxidizer used in rocket or jet propulsion. It generates thrust by expelling high-speed exhaust gases, crucial for space exploration and high-performance military aviation.
Pusher Propeller Configuration	In a pusher propeller configuration, the propeller is mounted at the rear of the aircraft, pushing rather than pulling it forward. This design reduces aerodynamic drag and enhances fuel efficiency.
Pushback Procedure	Pushback is the process of moving an aircraft backward from the gate using a ground tug. It is essential at large airports where aircraft need assistance maneuvering out of tight spaces.
Pylon (Aircraft Component)	A pylon is a structural support that connects engines, weapons, or fuel tanks to an aircraft’s fuselage or wings. Proper pylon design minimizes aerodynamic drag and enhances stability.