Lesson Plan
Performance Maneuvers: Steep Spiral
Purpose
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.
Elements
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.
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.
Constant airspeed: Maintaining a constant airspeed throughout a steep spiral is an important skill, since airspeed tends to fluctuate as the bank angle changes.
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.
Procedure
- Apply carb heat
- Close throttle
- Pitch and trim for best glide (Vg)
- Reduce pitch attitude
- Bank (not to exceed 60°)
- Establish a constant radius turn, adjusting bank to correct for wind drift
- Maintain constant airspeed
- 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 Practical Test Requirements
- Determine a ground-reference point and reference abeam
- Perform three 360° turns
- Manage a turn around the point with necessary wind-drift correction
- The bank should not exceed 60° (although a spirited maneuver will exceed 50°)
- Maintain ±10 knots airspeed
- Exit the maneuver ±10° entry heading after three complete rotations
More Information
More details are available in the Airplane Flying Handbook
Lesson Plan Checklist
Steep Spiral