and deflecting the right or left trailing edge of the parafoil—by moving the steering bars with the feet—which turns the aircraft right or left. Flaring is generally used to make fine adjustments in altitude when flying close to the ground and, in particular, when landing. In a powered parachute, flaring refers to pushing on both of the steering bars simultaneously, which causes the left and right trailing edges of the canopy to be pulled downwards at the same time. The result of this is that the airframe moves forward of the wing (on the transverse axis), airspeed is reduced, the angle of attack increases, and the aircraft temporarily gains additional lift. Done properly, the primary benefit of this maneuver is that it softens a landing (and especially an engine-out landing) within the last few feet off the ground. The power-off glide ratio of a PPC ranges from 3:1 to 6:1. Glide ratio varies depending on the chute size and shape. Engine-off landings are generally safe, provided that the aircraft is within glide range of a suitable landing zone and the pilot is properly trained in the use of proper flaring technique. Although possible, it is difficult to cause the aircraft to get into a dangerous attitude, stall, or chute collapse by means of pilot control inputs. Chute collapse is considered by many pilots to be virtually impossible with square wings. The wing is more likely to collapse with the more maneuverable, but inherently less stable, elliptical wing, but such collapses are normally followed by an immediate reflation and often go unnoticed by the pilot. In the rare circumstances where an elliptical wing collapses, the collapse is caused either by some extreme adverse meteorological condition or by pilot error. The FAA reports that over 80 percent of all aviation accidents are due to pilot error. Inflatable ram-air elliptical wings can have upward of 30 individual cells whereas square wings typically have fewer than 13 cells. The main hazards one faces while flying a PPC are associated with wind and obstacles. Flight should not be attempted in winds exceeding 10–15 mph or in gusty conditions. Wind hazards include terrain-induced air disturbances called rotors (it is advisable to stay upwind of trees, mountains, and other obstacles that disturb the flow of the wind). Wake turbulence created by the passage of other aircraft (referred to as "wingtip vortices"), especially aircraft that are heavy, aerodynamically