How the PITOT - STATIC system works (Private Pilot Ground Lesson 31)

Summary

This pilot training video delves into the workings of pedostatic instruments, crucial for flight navigation. It explains the function of the airspeed indicator, altimeter, and vertical speed indicator, which rely on air pressure from the pitot tube and static port. The video clarifies the concepts of static, dynamic, and total air pressure, and how these instruments can be affected by blockages or errors in the system. It also offers solutions for dealing with clogged ports, ensuring accurate flight data for safer flying.

Takeaways

• 🌀 The lesson discusses pedostatic instruments, which are the airspeed indicator, altimeter, and vertical speed indicator, using air pressure for flight information.
• 📡 These instruments receive air pressure data from the pitot tube and static port, which are crucial for accurate flight data.
• 🌪️ Air pressure types involved are static air pressure (ambient), dynamic air pressure (impact from air molecules on a moving object), and total air pressure (combination of static and dynamic).
• 📍 Static air pressure is measured in inches of mercury, with an average of 29.92 inches at sea level, decreasing by one inch per thousand feet above sea level.
• 🛫 The altimeter uses static pressure to provide altitude readings, with static ports usually placed on the side of the aircraft to avoid wind influence.
• 🔄 The vertical speed indicator senses pressure differences during climb or descent, providing readings in feet per minute.
• 🚀 The airspeed indicator measures the ram air through the pitot tube and offsets it with static air from the static port to determine airspeed accurately.
• ⚠️ The angle of the pitot tube can affect the airspeed indicator's accuracy, and manufacturers provide correction charts in the Pilot Operating Handbook (POH).
• 💧 The pitot tube has a 'weeping hole' to prevent water from clogging it, and heating elements can melt ice to avoid blockages.
• 🚨 If the pitot tube or static port is clogged, it can cause inaccurate readings in the airspeed indicator, altimeter, and vertical speed indicator.
• 🔄 In case of a clogged static port, newer training aircrafts may have an alternate static source to provide less accurate but usable data.
• 🔮 As a last resort, breaking the glass on a static instrument, preferably the vertical speed indicator, can provide some data in an emergency situation.

Q & A

What are the three primary flight instruments discussed in the script that use air pressure?

The three primary flight instruments discussed are the airspeed indicator, the altimeter, and the vertical speed indicator.

What are the three types of air pressure mentioned in the script?

The three types of air pressure mentioned are static air pressure, dynamic air pressure, and total air pressure.

What is static air pressure, and how is it measured?

Static air pressure, also known as ambient air pressure, is the pressure caused by the atmosphere. It is always present, whether the airplane is stopped or moving, and is measured in inches of mercury.

How does the static air pressure change with altitude?

The static air pressure decreases with increasing altitude, reducing by one inch of mercury for every thousand feet above sea level.

What is dynamic air pressure, and how does it relate to the aircraft's speed?

Dynamic air pressure is the pressure created on an object, like an airplane, as it moves through the air. It is directly related to the speed at which the aircraft is flying.

What is total air pressure, and why is it important for the pedostatic system?

Total air pressure is a combination of dynamic and static air pressure. It is important for the pedostatic system because it helps in accurately measuring the airspeed of the aircraft.

How does the altimeter use static pressure to provide altitude readings?

The altimeter uses a static port to sense the static pressure outside the aircraft. Since the static pressure changes with altitude, the altimeter can provide an altitude reading based on these changes.

What is the function of the vertical speed indicator, and how does it work?

The vertical speed indicator measures the rate of climb or descent of the aircraft. It allows air to escape or come in through a small hole vented through the static port, sensing pressure differences as the aircraft climbs or descends, and provides a reading in feet per minute.

How does the airspeed indicator measure airspeed, and what role does the pitot tube play?

The airspeed indicator measures the ram air that comes from the relative wind through the pitot tube. It also takes static air from the static port to offset any static air that might come in through the pitot tube, ensuring an accurate airspeed measurement.

What could potentially cause errors in the pedostatic instruments, and how can they be mitigated?

Errors in the pedostatic instruments could be caused by the pitot tube or static port getting clogged with bugs, mud, ice, or if water freezes in the pitot tube. These can be mitigated by using a heating element to melt ice or by using an alternate static source if available.

What is the 'weeping hole' on the pitot tube, and why is it important?

The 'weeping hole' is a small drain hole on the back of the pitot tube. It is important because it allows water that enters the front of the pitot tube to drain out, preventing clogging.

What should a pilot do if the static port gets clogged during flight?

If the static port gets clogged, the pilot can use an alternate static source if available, or as a last resort, break the glass on one of the static instruments, preferably the vertical speed indicator, to allow some form of pressure sensing.