Basic Flight Instruments
In this article I will show you the basic flight instruments, that are found in almost every airplane.
The Attitude Indicator
The attitude indicator or artificial horizon shows the orientation of the airplane relative to the earth. The upper half of the attitude indicator is blue, just like the sky (unless you fly in Belgium), the bottom is brown like the ground. The thin white line between these colours is the artificial horizon. The attitude indicator indicates pitch (up and down) and bank (rolling left and right). The pitch angle is indicated by the horizontal white lines above and beneath the artificial horizon with values in degrees. The bank angle is indicated by the arrow and small white lines at the top of the attitude indicator and by the white lines at different angles in the brown part of the attitude indicator, also in degrees.
Some examples:
The left attitude indicator on the picture above shows an airplane that is banking 5° to the left.
The middle attitude indicator shows an airplane that is banking 5° to the right.
The right attitude indicator shows an airplane that is flying straight and level. This means that the airplane doesn’t climb or descent and doesn’t bank to the left or right.
The Altimeter
The altimeter displays the altitude on which the airplane is flying, usually in feet or meters. The altimeter measures the local barometric pressure and shows it as an altitude above sea level. To obtain accurate and correct information, the altimeter must be calibrated according to the temperature and the movement of pressure systems in the atmosphere. You can do this with the knob on the left side of the altimeter.
- How to read the altimeter.
The altimeter has 2 hands and a dot representing the airplane’s height. The shorter, thicker hand represents altitude in thousands of feet. The long, thin hand represents the airplane’s altitude in hundreds of feet.
The easiest way to read an altimeter is to read it just like you would read a clock. For example, if Altimeter A were a clock, what time would it read? It would read 3 o’clock. Since Altimeter A isn’t a clock, it shows an altitude of 3000 feet. The long (hundreds) hand points to zero hundred feet and the medium (thousands) hand points to 3000 feet.
If altimeter B were a clock, what time would it say? It would read 3:30, or half past 3 o’clock. As an altimeter, it reads half past three thousand, or 3500 feet. The long (hundreds) hand points to 500 feet and the medium (thousands) hand points to between 3000 and 4000 feet. Thus, the altitude is 500 feet past 3000 feet (3500 feet).
What time would it be if Altimeter C were a clock? It looks like it would be somewhere around a quarter to seven. More precisely, the long (hundreds) hand shows 800 feet, and the medium (thousands) hand points to a little shy of 7000 feet. Therefore, the altimeter reads 800 feet past 6000 feet (6800 feet).
What time is it at Altimeter D? It looks like 3:00, but take a closer look at the very small dot. This dot points a little past a value of 1, meaning you need to add 10.000 feet onto the value shown by the altimeter’s medium and long hands. Thus, altimeter D indicates an altitude of 13.000 feet.
The airspeed indicator
This instrument shows the airspeed, typically in knots, to the pilot. The airspeed is relative to the surrounding air, so the airspeed is found by measuring the ram-air pressure in the pitot tube. The indicated airspeed must be corrected for air density (which varies with altitude, temperature and humidity) in order to obtain the true airspeed, and for wind conditions in order to obtain the speed over the ground.
The heading indicator
The heading indicator displays the heading of the aircraft. There are 360 degrees, the north is on 0°/360°, the east is on 90°, the south is on 180° and the west is on 270°. Most jet aircraft have a Horizontal Situation Indication (HSI) instead of a heading indicator. The HSI displays the heading, but provides also assistance with navigation.
Turn coordinator
This instrument displays the direction and rate of roll while the aircraft is rolling. The internally mounted inclinometer (the black dot in the white place) shows the ‘quality’ of the turn (coordinated or uncoordinated).
Vertical speed indicator
The vertical speed indicator or variometer senses changes in air pressure, and displays that information as a rate of climb or descent in feet per minute. If the airplane is flying straight, the white hand stands on zero.
Sources: FAA, FSX learning centre
