Anyone who has had the privilege of entering the cockpit of a transatlantic jumbo jet will be familiar with the overwhelming sight of the instrument panel before the pilots. It's hard to imagine what so many instruments could mean, and one can only feel respect and admiration for any pilot who can decipher them. But these are not basic instruments. They represent a highly sophisticated compilation of technical instruments which are not required in a humble recreational aircraft. In fact, the most basic aircraft of all, the ultralight airplane, needs only three instruments the air speed indicator, the variometer, and the altimeter.
The air speed indicator is vitally important to the safe operation of any aircraft. The new pilot quickly learns that air speed is a matter of life and death, because once it falls below the stall speed of the craft, the plane stops flying and, whatever the altitude, it's only a short trip to the ground. The pilot must be keenly aware of his aircraft's stall speed and stay well above it. Stall speeds tend to be very low in ultralight aircraft, less than 30 miles per hour, so the pilot must keep a careful eye on the air speed indicator at all times. The instrument does not read the aircraft's speed in relation to the ground, but only in relation to the air mass in which it is flying. An ultralight airplane facing a 35 mile per hour wind, and showing an air speed of 35 miles per hour, for example, will appear to be stationary to an observer on the ground.
Once in the air, the pilot needs to establish level flight by reducing the throttle setting. The aircraft will gradually stop climbing as the power is cut back, but reference to the variometer reading is needed to ensure that level flight is maintained. The variometer is sometimes called the vertical speed indicator, because its function is to show whether the plane is rising or falling. It reads in feet per minute. A plus reading indicates that the plane is rising and a negative reading shows the rate of fall. For level flight, the pilot must maintain a reading of zero.
All pilots need to know the exact altitude at which they are flying because air regulations stipulate specific altitudes according to direction and land features. This is particularly important for recreational aircraft pilots. Ultralight airplanes normally fly below 5000 feet and obstacles such as radio towers can be a problem to pilots who are not properly aware of altitude. A good, accurate altimeter is needed for safety. Altimeters generally read in hundreds of feet and should be set to sea level in most aircraft. However, ultralight pilots who do not travel far from base often set their altimeters to zero at ground level before take off. This allows for convenient reading and comparison of local obstacles indicated on aviation maps.
These are the three most basic and essential instruments for recreational flying. Other instruments such as compass for exact heading, engine temperature, slip and roll indicator, etc. can easily be added if desired. In general, the more sophisticated the aircraft, the more instruments it requires.