Some operations such as search and rescue, fire patrol, and wildlife management will require flying closer to the ground. Recreational pilots may also want to make scenic flights in mountainous areas or land at mountain airports. These operations can be accomplished safely, provided that the pilot has undergone the proper training. A fundamental rule of mountain flying is that pilots should always remain in a position where they can turn toward lower terrain. Canyons should be flown downstream rather than upstream—enter from the top at an altitude above the highest point and then fly down the canyon toward the lower elevation. Flying up a canyon is like driving the wrong direction on a freeway. Divide the canyon into thirds and fly along one side—never in the middle. In addition to exposing you to shear turbulence, the middle of the canyon will place you in a poor position to turn around and make a course reversal. Slowing down and even adding flaps will greatly reduce the turn radius if it becomes necessary to reverse course. Turning radius increases with the square of the speed (turning radius at 70 knots is 436 feet; at 140 knots it is four times greater—1,744 feet). Begin the turn with an aggressive bank while keeping the nose down to avoid a stall. You can always moderate the amount of bank once you've turned partially around. If you're not aggressive from the start, you can find yourself out of room to complete the maneuver on the other side of the canyon. Fly along the sunny side of the slope in calm winds to take advantage of rising air currents heated by the sun. Fly on the downwind side of a canyon in strong winds to avoid rotors and turbulence. Climb gradients for small aircraft in mountainous areas will typically range from 100-200 feet per nautical mile depending on the groundspeed. If in doubt about your ability to clear terrain, turn around.