by Jonathan M. Stern
Ground Reference Maneuvers
My flight students often questioned the need to do clearing turns before maneuvers...until the clearing turns themselves revealed aircraft dangerously close to us.
Ground reference maneuvers are performed closer to the ground than are stalls and slow flight practice. Accordingly, you need to stay in the practice area but descend to an altitude 800 feet above the ground, which is approximately 1,400 feet.
You can perform descents with or without power. A descent made with power off (at idle or after an engine failure) is called a glide, In a glide, the power is fixed, albeit at zero, so pitch must be used to control airspeed.
The aerodynamics of the Cessna 182RG are such that the greatest horizontal distance (assuming no wind and a fully loaded airplane) is achieved with an indicated airspeed of 80 knots. In these conditions, the airplane glides 10 nautical miles from 6,000 feet of elevation. Any change in pitch that results in a higher or lower indicated airspeed, however, decreases the distance that the airplane will glide (see Figure 5.1).
Figure 5.1. Any speed higher or lower than the best glide speed reduces the distance that the airplane can cover without power.
In other words, avoid the instinct to stretch the glide by raising the nose. Such action shortens the glide distance.
To enter a power off descent from cruising flight, perform the following steps:
- Reduce the throttle to idle power.
- Enrich the mixture as required (you still have the mixture control de-selected).
- Maintain altitude by increasing control yoke back pressure while the airspeed bleeds off toward best glide speed.
- As the airplane reaches the best glide speed, release the back pressure on the control yoke just enough to allow the airplane to establish the nose low attitude that will maintain the best glide speed.
- Adjust pitch as necessary to maintain the best glide speed.
When approaching the desired altitude, the leveloff procedures must be initiated, usually 50 to 100 feet before reaching the desired altitude. First, the power should be advanced to cruise flight setting. Increasing the power causes the nose to rise, and it may be necessary to apply some forward pressure on the control yoke to complete the descent. Use pitch control to maintain the desired altitude, and make any necessary adjustments to the throttle and mixture controls.
Reset the Airwork situation and practice a gliding descent. For additional instruction and practice of descents, select "Lesson 7—Slow Descents" from the Options/Flight Instruction menu (Basic Category).
Ground reference maneuvers are beneficial for teaching pilots to observe, understand, and analyze the effects of wind while controlling the airplane. Although there are numerous varieties of ground reference maneuvers, we will try three: rectangular course, s-turns across a road, and turns about a point. For each of them, go ahead and program winds aloft into the simulation.
To do so, follow these instructions:
- Select the Airwork situation from the Options/Situation menu.
- Select the World/Weather menu.
- Select Winds/Winds Aloft.
- Create a wind layer with a 700' base and a 5,000' top.
- Set wind direction to 270°.
- Set wind speed to 30 knots.
- Press Enter twice.
- Save the revised situation as Windwork.