Minimum Contollable Airspeed

Teaching and Learning Flying - Private Pilot, Single-Engine Airplane

Minimum Controllable Airspeed

DEFINITION

Minimum controllable airspeed (MCA) is the slowest airspeed at which straight and level controlled flight can be maintained. This is usually within +5 knots of stall speed. At MCA, any further increase in load factor or angle of attack or loss of power will result in a stall.

SAFETY FACTORS

Begin the maneuver above 2,000 feet AGL to allow altitude for safe inadvertent stall recovery
Lights ON and CLEAR area with two 90o turns, left and right
After power reduction during entry, adjust mixture rich and prop in high RPM
Monitor carburetor temperature and CHT
Divide attention between outside and instrument references and watching for traffic

TOLERANCES

Student explains flight characteristics and controllability associated with flight at MCA
Selects an entry altitude above 1,500 feet AGL (>2000 feet AGL)
Establishes and maintains coordinated flight at MCA in SLF and level turns in specified configurations and bank angles
Private Pilot PTS:
- airspeed +5, -0 knots
- altitude +/-100 feet
- heading +/-10o
- bank angle +/-10o
Commercial Pilot PTS:
- airspeed 5 +/-5 knots above stall speed
- altitude +/-50 feet
- heading +/-10o
- bank angle +/-5o

OBJECTIVES

To develop the student's sense of feel and ability to use the controls correctly, and to improve proficiency and safety in performing maneuvers in which very low airspeeds are required
To develop the student's ability to determine the characteristic control responses of an airplane in order to avoid stalls during flight at the slower airspeeds used for takeoffs, climbs, and landing approaches

PROCEDURES

PREFLIGHT
- Discuss definition, tolerances, objectives of flight at MCA
- Discuss elements of flight at MCA
  - Safety factors
    - Altitude for stall recovery above 1,500 feet
    - Aircraft configured for recovery (mix RICH, prop IN HIGH RPM)
  - Draw and explain power vs airspeed curve
    - Maximum endurance speed
    - Region of reverse command
  - Entry and recovery technique
INFLIGHT
- Demonstrate flight at MCA
  - Cessna TR182, N6209T:
  - Above 2,000 feet
  - Lights ON; CLEAR area
  - During second clearing turn, retard throttle gradually to <15 in. MP while gradually raising nose to maintain altitude
  - Mixture rich; prop control advanced to high RPM
  - Check carburetor temperature and cylinder head temperature
  - Configure airplane as desired as airspeed slows
    - Gear down < 140 KIAS
    - Flaps 10o < 140, 20o < 120, and full < 95 KIAS
    - Trim for 45-50 KIAS
  - Add power as needed to maintain altitude
  - Simplified, one power step,"left to right" slow flight technique:
    - Gear down < 140 KIAS
    - Check carb temp
    - Power back to 19 in. MP
    - Prop IN HIGH RPM
    - Mixture RICH
    - Flaps extended one notch at a time as above
  - Turns may require slight increase in power
  - Re-establish cruise:
    - Confirm: mix RICH, prop IN HIGH RPM
    - Power to 30 in. MP
    - Flaps up to 20o, and gear up
    - Flaps up 10o, 0o
    - Readjust MP, RPM , mixture
- Instructor coaches student practice
POSTFLIGHT
- Instructor critiques student performance

COMMON ERRORS

Failure to establish specified configuration
Improper entry technique
Failure to establish and maintain the specified airspeed
Excessive variation of altitude, heading and bank
Rough or uncoordinated control technique
Faulty trim technique
Unintentional stall
Inappropriate removal of hand from throttle
Allowing torque to pull airplane off desired heading

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