What are the main aircraft instruments and what do they do?
The main aircraft instruments show airspeed, attitude, altitude, turn, heading and vertical speed. Together, these primary flight instruments tell the pilot how the aircraft is moving and oriented. Engine, fuel, navigation and system instruments show powerplant health, fuel state, position, aircraft configuration and developing faults.
For Aviation & Real-World Flying, we separate the six primary flight indications from the supporting instruments. The exact panel, sensors and power sources vary by aircraft, but the information pilots need remains broadly the same.
What are the six primary flight instruments?
The traditional aircraft six-pack consists of the airspeed indicator, attitude indicator, altimeter, turn coordinator, heading indicator and vertical-speed indicator.
| Instrument | What it shows | What pilots must remember |
|---|---|---|
| Airspeed indicator | Indicated airspeed derived from pitot and static pressure, usually displayed in knots. | Indicated airspeed is not the same as true airspeed or groundspeed. Its coloured arcs and markings identify operating ranges and limitations. |
| Attitude indicator | Aircraft pitch and bank relative to the horizon. | It shows attitude, not flight path. An aircraft can be nose-up while descending if it lacks sufficient airspeed or power. |
| Altimeter | Altitude calculated from static air pressure. | The barometric setting must be correct. A conventional altimeter does not directly show height above the ground. |
| Turn coordinator | Direction and approximate rate of turn; its inclinometer ball shows slip or skid. | The miniature aircraft is not an attitude display. Some panels use a turn-and-slip indicator instead. |
| Heading indicator | Aircraft heading on a stable directional display. | An unslaved gyroscopic instrument drifts and must be checked against the magnetic compass. Heading also differs from ground track when wind is present. |
| Vertical-speed indicator | Rate of climb or descent, normally in feet per minute. | Traditional units lag behind the aircraft's actual movement, so chasing the needle causes poor altitude control. |
On a conventional panel, the top row is normally airspeed, attitude and altitude; the lower row is turn, heading and vertical speed. Simmers can compare that arrangement using our examples of MSFS aircraft fitted with steam-gauge panels.
What other aircraft instruments are essential?
Engine, navigation and system instruments are essential because the six-pack cannot show powerplant condition, position, fuel state or equipment faults.
| Instrument group | Typical indications | Purpose |
|---|---|---|
| Magnetic compass | Magnetic heading | Provides a basic heading reference, but is subject to deviation, dip, acceleration and turning errors. |
| Engine instruments | RPM, manifold pressure, oil pressure, oil temperature, fuel flow, torque, N1/N2, EGT or ITT | Show power output and engine health. The exact set depends on whether the aircraft has a piston or turbine engine. |
| Fuel instruments | Tank quantity, fuel pressure, flow and used fuel | Help monitor supply and consumption. Fuel gauges do not replace pre-flight measurement and fuel planning. |
| Navigation instruments | CDI, HSI, bearing pointer, distance, GNSS position and moving map | Show course guidance, position and progress along a route. |
| System instruments | Electrical load and voltage, hydraulic pressure, vacuum or suction, cabin pressure, gear and flap position | Confirm that aircraft systems are operating and configured correctly. |
| Warning displays | Warning, caution, advisory and status messages | Draw attention to faults or configurations requiring action. |
For a familiar light-aircraft example, our panel-by-panel explanation of a Cessna 172 shows how the primary instruments sit alongside engine gauges, switches and controls.
How do glass cockpit instruments differ?
Glass cockpits combine the same fundamental information on electronic displays instead of assigning one mechanical gauge to each measurement.
A primary flight display normally places attitude in the centre, airspeed on the left, altitude and vertical speed on the right, and heading or track along the bottom. It may also show flight-director commands, navigation guidance, trend predictions and autopilot mode annunciations. A multifunction display commonly carries the moving map, traffic, weather, engine data and system pages.
This consolidation improves presentation but can concentrate several indications on one display or data source. Aircraft therefore use warning flags, reversionary modes and standby instruments according to their design. Airliner presentation adds more automation and mode information; our guide to reading conventional indications on an Airbus A320 PFD explains a typical example.
What happens when an aircraft instrument fails?
Instrument failures often affect groups of indications because several instruments may share the same pressure source, electrical bus, air-data computer or attitude sensor.
| Failure source | Likely clues |
|---|---|
| Pitot blockage | The airspeed indication becomes unreliable. With the pitot inlet blocked but its drain open, it may fall towards zero; if pressure is trapped, it can change incorrectly with altitude. |
| Static blockage | The altimeter may freeze, the vertical-speed indicator settles near zero, and the airspeed indicator develops altitude-dependent errors. |
| Gyro or vacuum failure | On many traditional light-aircraft installations, the attitude and heading indicators may topple, drift or respond sluggishly. The affected instruments depend on how that aircraft powers them. |
| Electrical failure | Electronic displays, navigation equipment and electrically powered gyros may be lost. Battery, standby and essential-bus arrangements differ between aircraft. |
| Air-data or attitude-sensor fault | A glass cockpit may flag several values as invalid, display warning crosses or transfer information to another screen. |
A believable but frozen instrument can be harder to identify than a blank display. Pilots detect it by cross-checking independent indications: pitch attitude should agree with airspeed and vertical-speed trends, while heading changes should agree with the compass and turn indication.
Which aircraft instrument readings are commonly misunderstood?
The most common mistakes come from treating related measurements as interchangeable.
- Indicated airspeed is not groundspeed. Wind changes groundspeed, while altitude and temperature affect the relationship between indicated and true airspeed.
- Altitude is not height above terrain. A pressure altimeter normally references a pressure datum, not the ground directly below the aircraft.
- Heading is not track. Heading is where the nose points; track is the path made over the ground.
- The inclinometer ball is not a bank indicator. It shows whether a turn is coordinated, slipping or skidding.
- The vertical-speed indicator should not be chased. Confirm a climb or descent using attitude, altitude trend and airspeed as well.
- A glass display does not make every source independent. Multiple values can originate from one air-data computer or attitude and heading reference system.
Exact limitations, standby arrangements and failure procedures vary even between variants of the same aircraft. For real flight, the approved flight manual, operating handbook and aircraft checklist take precedence over any generic instrument description.