The steep spiral is a performance maneuver that rapidly dissipates substantial amounts of altitude while remaining over a selected spot. It would be practically used for effective for emergency descents or landings.

In practical terms, mastery of the steep spiral improves a pilot's confidence in his or her ability to execute a rapid loss of altitude in order to execute an emergency descent or off-airport landing. However, is is distinct from the maximum-speed Emergency Descent maneuver in the Commerical/CFI ACS.

The steep spiral improves pilot techniques for airspeed control, wind drift control, planning, orientation, and division of attention.

Performance and Ground Reference: The steep spiral is categorized as a performance maneuver, but it also is a ground reference maneuver, because it requires varying bank angles to make a desired ground track.

Similar to turns around a point: In a steep spiral, the pilot maintains a constant radius around a surface-based reference point while rapidly descending.

Three complete turns: At least three 360° turns are completed in the maneuver, terminating no lower than 1,500 AGL.

Constant-radius turns: With idle power and bank less than 60°, a constant-radius turn is accomplished by correcting for wind drift.

• Use steeper angles as the airplane turns into a headwind and shallower angles when the airplane has a tailwind.

Not really a "spiral": A "spiral" is a curve that emanates from a point and moves further away as it revolves around a point. This maneuver requires three constant-radius turns.

Airspeed at or below Va: Use an airspeed that is at or below maneuvering speed during the maneuver. Before introducing the bank, you can slow the aircraft to its best glide airspeed (Vg).

Ground reference selection: The ground reference's initial position should be near the main gear (in a high-wing airplane), or directly in front of the wing (in a low-wing airplane).

Constant airspeed: Maintaining a constant airspeed throughout a steep spiral is an important skill, since airspeed tends to fluctuate as the bank angle changes.

Expect to vary pitch: A constant airspeed will require pitching up when the bank is steep and pitching down when the bank is shallow.

Division of attention: The pilot can expect to divide his or her attention between the instruments and the flight environment.

The reference point moves away: Since the goal is constant-radius turns (concentric circles), the ground reference will move away from the airplane reference. Otherwise, each radius will become smaller as the airplane approaches the surface.

Wind direction can vary: Expect the wind direction and velocity to change during the descent through different altitudes.

Clear the engine: During a steep spiral, the throttle should be periodically advanced to normal cruise power and sustained for a few seconds.

• Operating the engine at idle speed for any prolonged period during the glide may result in excessive engine cooling, spark plug fouling, or carburetor ice.
• A cylinder head temperature gauge can provide the pilot with insight on engine cooling.

Roll out on reference or heading: After three turns, the pilot should roll out toward a definite object or on a specific heading, recovering to a wings-level glide with no change in airspeed, followed by normal cruise flight, landing at an airport, or simulating an off-airport landing.

Procedure

• Determine wind direction
• Start procedure on a downwind heading
• Apply carb heat
• Close throttle
• Pitch and trim for best glide (Vg)
• Reduce pitch attitude
• Airspeed at or below Va
• Steep bank (not to exceed 60¡)
• Establish a constant radius turn, adjusting bank to correct for wind drift
• Maintain constant airspeed with pitch adustments
• Evaluate groundspeed with GPS
• Advance throttle at each 360¡ position
• After three turns, roll level at a heading or outside reference
• Glide wings level at Vg airspeed

Common Errors

Common errors when performing steep spirals include:

• Not clearing the area
• Inadequate pitch control on entry or rollout
• Gaining altitude
• Not correcting the bank angle to compensate for wind
• Poor flight control coordination
• Ineffective use of trim
• Inadequate airspeed control
• Becoming disoriented
• Performing by reference to the flight instrument rather than visual references
• Not scanning for other traffic during the maneuver
• Not completing the turn on designated heading or reference

Completion Standards

Commercial Pilot & CFI Airmen Certification Standards (ACS)

• Select an altitude sufficient to continue through a series of at least three 360° turns.
• Establish and maintain a steep spiral, not to exceed 60° angle of bank, to maintain a constant radius about a suitable ground reference point.
• Apply wind drift correction to track a constant radius circle around selected reference point with bank not to exceed 60° at steepest point in turn.
• Divide attention between airplane control and ground track, while maintaining coordinated flight.
• Maintain the specified airspeed, ±10 knots, rolls out toward object or specified heading, ±10°.