Slow Flight

OBJECTIVE: To develop the pilot’s sense of feel and ability to use the flight controls correctly, and to improve proficiency in maneuvers that require slow airspeeds. 
ELEMENTS
Relationship of configuration, weight, center of gravity, maneuvering loads, angle of bank, and power to flight characteristics and controllability
Relationship of the maneuver to critical flight situations, such as go-around
Performance of the maneuver with selected landing gear and flap configurations in straight-and-level flight and level turns
Specified airspeed for the maneuver
Coordination of flight controls
Trim technique
Recovery to cruise flight

COMPLETION STANDARDS
  • Exhibits knowledge of the elements related to maneuvering during slow flight 
  • Selects an entry altitude that will allow the task to be completed no lower than 1500 feet AGL 
  • Establishes and maintains an airspeed at which any further increase in angle of attack, increase in load factor, or reduction in power, would result in an immediate stall 
  • Accomplishes coordinated straight-and-level flight, turns, climbs, and descents with landing gear and flap configurations 
  • Divides attention between airplane control and orientation 
  • Maintains the specified altitude, ±100 feet; specified heading, ±10°; airspeed, +10/−0 knots; and specified angle of bank, ±10° 

COMMON ERRORS
  • Failure to establish specified gear and flap configuration 
  • Improper entry technique 
  • Failure to establish and maintain the specified airspeed 
  • Excessive variations of altitude and heading when a constant altitude and heading are specified 
  • Rough or uncoordinated control technique 
  • Improper correction for torque effect 
  • Improper trim technique 
  • Unintentional stalls 
  • Inappropriate removal of hand from throttles 
  • Failure to adequately clear the area 
  • Inadequate back-elevator pressure as power is reduced, resulting in altitude loss 
  • Excessive back-elevator pressure as power is reduced, resulting in a climb, followed by a rapid reduction in airspeed and “mushing” 
  • Inadequate compensation for adverse yaw during turns 
  • Fixation on the airspeed indicator 
  • Failure to anticipate changes in lift as flaps are extended or retracted 
  • Inadequate power management 
  • Inability to adequately divide attention between airplane control and orientation 
THINGS TO REMEMBER
  • How slow flight relates to airspeeds required for landings 
  • Trim to ‘Hands Off’ 
  • Maximum nose up trim is minimum sink speed in several trainers 
  • Watch the VSI. As the airspeed falls, the VSI will begin a downward motion. Once this happens, add the first notch of flaps. That will cause the aircraft to balloon upwards, but eventually the speed will decrease again and a downtrend will develop in the VSI. Each time this happens add another notch of flaps until you get to full flaps (note the lack of trim change required). 
  • Maneuver can lead to a normal fear response, allow the student to be in full control of the aircraft and slow as much as is slightly uncomfortable, and keep working at it until they are able to do the standard comfortably. 
  • Considerations for vertical maneuvering 
  • Pitch to hold vertical speed (VSI, then ALT) and power to modify airspeed while entering slow flight. 
  • In maneuver, pitch to control airspeed, power to control VSI then altitude.
  • Power changes: adding power slows aircraft, must use pitch to maintain. 
  • Many pilots have a misconception about the desired airspeed; they think the airspeed is at 1.2 Vs1, +10/-5 KIAS, and it is not. The PTS calls for airspeed right at the edge of stall, in all configurations. In most light aircraft this is slower than full-flaps normal approach airspeed. 
  • Most people do not take advantage of the natural trim tendencies of the airplane, and they work way to hard, trimming up as we slow down, and then back down again when adding flaps and power. In the end, the net trim change is very small. 
  • Goal is to be better than minimum FAA standards. Be able to precisely control aircraft in slow flight, up to 30° of bank with a level altitude. 

Instructor: Distract student during pre-solo slow flight practice. The goal is to get the student to inadvertently stall the aircraft and recover despite their surprise. If they can't recover, they are not ready to solo. 


TRICKS
  • This procedure gets you into the maneuver with very little trim change. The downward trim changes caused by the decreasing airspeed are offset by the upward trim changes created by the flaps and power.
  • Yes it takes longer; that’s OK. There is no time limit in the PTS for setting up minimum controllable airspeed (MCA). Don’t rush it; that’s when you will screw it up.
  • Once in MCA, control airspeed with pitch and vertical speed with power. To change/correct altitude, use power changes.
  • Exaggerate rudder inputs when rolling the airplane. Adverse yaw is more pronounced at low airpseeds. 
  • When maneuvering, pitch or roll the aircraft very slowly. While the inertia of the aircraft is unchanged, the aerodynamic stabilizing forces are decreased at the low airspeed, and there is a tendency to overshoot pitch and bank changes; especially true in roll, since adverse yaw is more pronounced; roll will be very sluggish. If you ever get it rolling fast, it will be hard to stop it smoothly or close to where you want it. Better to never let it get moving that fast in the first place. 
  • For turns, add some power if the bank is greater than 10°. Learn what power setting it takes to maintain 0 VSI, at 1.2 Vs1 and MCA, in 10°, 20° and 30° banks. Remember to take the power back out as you roll out. 
  • Ask pilot: In MCA, when will the pitch attitude in level flight be higher: MCA in a clean or landing configuration? 

STUDY
  •  “Airplane Flying Handbook” Ch. 4

Slow Flight Procedure

  • Clearing Turns 
  • Execute pre-landing checklist, hold the flaps for now 
  • Choose a visual reference on the horizon; point it out and align the aircraft with it 
  • Reduce power (or, in complex aircraft, extend landing gear) 
  • Larger power reduction make this harder maneuver 
  • In most trainer aircraft ~ 1800RPM-2000RPM 
  • Remind pilot to change rudder pressure for 0 rate of turn 
  • Pitch and trim for 0 VSI, hands off 
  • When back pressure substantial, release tiny bit 
  • First notch of flaps (relieves back pressure) 
  • Move elevator to maintain level (0 VSI) 
  • Pitch down, then up for zero rate of climb 
  • As speed decreases, flaps second setting to relieve back pressure 
  • As speed decreases, flaps third setting to relieve back pressure 
  • Continue backpressure at zero rate of climb until stall 
  • Add power (~2200-2300 RPM) that gives level flight 
  • Maintain pitch at level, rudder for zero rate of roll 
  • TRIM for zero rate of climb, TRIM rudder at zero rate of roll 
  • Recover with full power and reversing the process 
  • Complete Cruise Checklist