• The radius of the turn and the path of the  powered parachute over the ground should be  easily noted and changes planned and effected  as circumstances require. • Drift should be easily discernable, but not tax  the student too much in making corrections. • The altitude should be low enough to render  any gain or loss apparent to the student, but  in no case closer than 500 feet to the highest  obstruction or lower then 200 feet above the  ground. a straight course to that point without drifting. How- ever, if the river were flowing swiftly, the water cur - rent would have to be considered. That is, as the boat  progresses forward with its own power, it must also  move upstream at the same rate the river is moving  it downstream. This is accomplished by angling the  boat upstream sufficiently to counteract the down - stream flow. If this is done, the boat will follow the  desired track across the river from the departure point  directly to the intended destination point. Should the  boat not be headed sufficiently upstream, it would  drift with the current and run aground at some point  downstream on the opposite bank. [Figure 9-1] During these maneuvers, both the instructor and the  student should be alert for available forced-landing  fields. The area chosen should be away from com - munities, livestock, or groups of people to prevent  possible annoyance or hazards to others. Due to the  altitudes at which these maneuvers are performed,  there is little time available to search for a suitable  field for landing in the event the need arises. As soon as a powered parachute becomes airborne,  it is free of ground friction. Its path is then affected  by the air mass in which it is flying; therefore, the  powered parachute (like the boat) will not always  track along the ground in the exact direction that it is  headed. When flying with the longitudinal axis of the  powered parachute aligned with a road, the powered  parachute may get closer to or farther from the road  without any turn having been made. This would indi- cate the air mass is moving sideward in relation to the  powered parachute. Since the powered parachute is  flying within this moving body of air (wind), it moves  or drifts with the air in the same direction and speed,  just like the boat moved with the river current. [See  Figure 9-1] Whenever any object is free from the ground, it is  affected by the medium with which it is surrounded.  This means that a free object will continue to move in  its current direction and speed unless acted upon by  another force. For example, if a powerboat is cross- ing a river and the river is still, the boat could head  directly to a point on the opposite shore and travel on  Drift and Ground Track Control Figure 9-1. Wind drift.  9-2