Introduction to Aviation

Resource personAli Khalid

Department of Aviation Management & Technology Superior University, Lahore.

Learning Objectives

By the end of this session , you will be able to:

Understand the basics of aircraft instruments .

Instrument

What is an instrument ???

A mechanical implement or tool, esp one used for precision work.

In other words we can say that we use instruments (of any type) to measure something more accurately?

Any example ?

Instruments

Thermometer is an instrument?

Yes, because we measure temp through It more precisely

Similarly watch is also an instrument used For measuring time.

Intro to aircraft instruments The use of instruments as an aid to flight

enables the pilot to operate the airplane more precisely, and therefore, obtain maximum performance and enhanced safety.

This is particularly true when flying greater distances

Aircraft instruments

Since the beginning of manned flight, it has been recognized that supplying the pilot with information about the aircraft and its operation could be useful and lead to safer flight.

The Wright Brothers had very few instruments on their Wright Flyer, but they did have an engine tachometer, an anemometer (wind meter), and a stop watch.

Aircraft instruments

From that simple beginning, a wide variety of instruments have been developed to inform flight crews of different parameters. Such as altitude, heading etc

Instrument systems now exist to provide information on the condition of the aircraft, engine, components, the aircraft’s attitude in the sky, weather, cabin environment, navigation, and communication.

Aircraft instruments

various instrument panels from the Wright Flyer to a modern jet airliner are shown below

Types of system

There are usually two parts to any instrument or instrument system.

One part senses the situation and the other part displays it.

In analog instruments, both of these functions often take place in a single unit or instrument. These are called direct-sensing instruments.

Types of sys

Remote-sensing requires the information to be sensed, or captured, and then sent to a separate display unit in the cockpit.

Ways to transfer information The relaying of important bits of information

can be done in various ways :

Electricity is often used by way of wires that carry sensor information into the cockpit.

pneumatic lines are used.

More efficient information transfer has been accomplished via the use of digital data buses.

Classifying Instruments

There are three basic kinds of instruments classified by the job they perform: flight instruments, engine instruments, and navigation instruments.

Flight Instruments

The instruments used in controlling the aircraft’s flight attitude are known as the flight instruments.

There are basic flight instruments, such as the altimeter that displays aircraft altitude; the airspeed indicator; and the magnetic direction indicator, a form of compass.

Basic T arrangement

Additionally, an artificial horizon, turn coordinator, and vertical speed indicator are flight instruments present in most aircrafts.

Engine Instruments

Engine instruments are those designed to measure operating parameters of the aircraft’s engine(s).

These are usually quantity, pressure, temperature indications and engine speeds. We measure the above mentioned parameters through these instruments.

The most common engine instruments are the fuel and oil quantity and pressure gauges, tachometers, and temperature gauges.

Navigation Instruments

Navigation instruments are those that contribute information used by the pilot to guide the aircraft along a definite course.

It includes compasses of various kinds, some of which use the radio signals to tell pilot a specific course while flying the aircraft en route from one airport to another.

Other navigational instruments are designed specifically to direct the pilot’s approach to landing at an airport.

contd

A few years back Radios and instruments sending locating information via radio waves to the ground but those systems are now overcome by the more advance technology of Global position systems (GPS) which uses satellites to pinpoint the location of the aircraft via geometric triangulation.

Pitot-Static Systems

Some of the most important flight instruments derive their indications from measuring air pressure.

Gathering and distributing various air pressures for flight instrumentation is the function of the pitot-static system.

The pitot-static system is a combined system that utilizes the static air pressure, and the dynamic pressure due to the motion of the aircraft through the air.

It is widely used to determine the airspeed of an aircraft and to measure air velocity.

Pitot system

The altimeter, airspeed indicator, and vertical speed indicator are the three most common pitot-static instruments.

contd

The pitot-static tube is mounted on the outside of the aircraft at a point where the air is least likely to be turbulent or where the air pressure is likely to be the highest.

examples

Cutaway

Static vents

The static pressure is obtained through a static port.

Separate static vents are used to collect static air pressure information. Usually, these are located on the side of the fuselage.

Fuction

To capture impact air pressure and static air pressure and direct them to the proper instruments.

As this tube contains fluid (air), a pressure can be measured; the moving air is brought to rest as there is no outlet to allow air to continue.

This pressure of the air, also known as the total pressure or (particularly in aviation) the pitot pressure.

Calculation

total pressure = static pressure + dynamic pressure

So dynamic pressure = total pressure – static pressure

Air Data Computers (ADC)

High performance and jet transport category aircraft pitot-static systems may be more complicated.

These aircraft frequently operate at high altitude where the ambient temperature can exceed 50 °F below zero.

Airflow around the fuselage changes, making it difficult to pick up consistent static pressure inputs.

Therefore the use of an air data computer (ADC) is common for these purposes on high-performance aircraft

Moreover, modern aircraft utilize digital air data computers (DADC). The conversion of sensed air pressures into digital values makes them more easily manipulated by the computer to output accurate information.