Cockpit Instruments

Instruments in an aircraft’s cock­pit show the pilot what is hap­pening to the aircraft and how well it is flying. The instruments are especially important when a pilot cannot see the ground because of cloud, fog, or dark­ness. They enable a pilot to keep an aircraft flying safely in the right direction. The instruments also can warn pilots of dangers, such as fire in an engine or flying too close to the ground.

Glass Cockpits

Modern cockpits often have several screens, like computer screens, which combine the functions of many separate instruments. This kind of cockpit is called a glass cockpit.

There are three types of screens in a glass cockpit. The first is the primary
flight display, which shows the airspeed, altitude, heading, and vertical speed. There is a primary flight display in front of each pilot.

The next screen is the navigation display, which shows the aircraft’s posi­tion and course. The picture from the aircraft’s weather radar also can be

TECH^TALK

There are seven basic flight instru­ments in an airplane:

• Airspeed indicator shows an aircraft’s speed compared to the surrounding air.

• Altimeter shows an aircraft’s height above sea level, or altitude.

• Attitude indicator shows an aircraft’s attitude (the way it is pointing) compared to the horizon.

• Magnetic compass shows an aircraft’s heading (direction).

• Heading indicator also shows heading but works in a different way from the magnetic compass.

• Turn and bank indicator shows if an aircraft is turning correctly.

• Vertical speed indicator shows how fast an aircraft is climbing or descending.

The magnetic compass works by sensing the direction of Earth’s mag­netic field. It works fine in steady flight, but it can be unreliable if the plane is climbing, diving, or turning.

The heading indicator (which is based on a gyroscope) is used to double-check it.

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shown on this screen. A small business jet might have one navigation display in the middle. A larger airliner may have a separate navigation display in front of each pilot.

The third type of screen is linked to the engine indicating and crew alerting system (EICAS). It shows engine infor­mation and emergency warnings. In addition, an aircraft’s flight computer has its own small screens.

A glass cockpit can greatly reduce the number of instruments and controls. The glass cockpit of the Boeing 747-400 has 365 instruments and switches – about 600 fewer than the cockpits in earlier 747s. A glass cockpit also has a basic set of old-style instruments to provide an emergency backup if the cockpit screens fail.

Glass cockpits have proved to be so reliable and effective that spacecraft now have them as well. The Space Shuttle and Soyuz spacecraft are fitted with their own glass cockpits.