The following stories from the February 8, 2008, edition of AOPA ePilot were provided to AOPA members who expressed an interest in the particular subject areas. Any AOPA member can receive information tailored to their areas of interest by updating their preferences online.
My ePilot - Student Interest, Training Tips
IN-FLIGHT FLAP RETRACTION?
The Feb. 1 "Training Tip" discussed the timing of flap deployment for landings. If flaps are deployed too much or too soon, why are you advised not to retract them to correct the situation? The risk is that retracting flaps at low altitude and low airspeed can dangerously destabilize the approach by generating temporarily high sink rates and bringing the aircraft closer to a stalled angle of attack. This question is often encountered when a student pilot adds flaps on final approach, then realizes that the new glide angle is too steep. "Never retract the flaps to correct for undershooting since that will suddenly decrease the lift and cause the airplane to sink even more rapidly," cautions Chapter 8 of the Airplane Flying Handbook .
Adding power to shallow the glide angle is the remedy of choice. If it's too late for that, go around. Remember, however, that a similar risk must be taken into account during the go-around, so follow your aircraft's recommended procedure exactly.
To help you understand the risk of retracting the flaps, consider the effect flap retraction has on stall speed, explained in AOPA Air Safety Foundation Executive Director Bruce Landsberg's instructional article on the AOPA Flight Training Web site. "If the pilot retracts the flaps too quickly, there is usually a sinking spell and sometimes a stall; so, adding just enough back pressure to keep from sinking is something else to add to the skills list. On the Beech V35 Bonanza, the stall speed increases by about 12 knots as the flaps come up. On the Cessna 172, it's around seven knots; on the Piper Arrow, it's about five knots."
Are there exceptions? One might be the unlikely case of an engine failure on final with full flaps. "Yes, the flaps can and probably should be retracted at such a time, but some pilots might have difficulty coping with the unexpected trim change and momentary increase in sink rate that would occur at such a critical time," wrote AOPA Pilot columnist Barry Schiff in a "Proficient Pilot" column discussing how and when to use full flaps.
Flaps make landings easy and accurate, but don't make a bad situation worse by improvising with their use!
My ePilot - Training Product
ASA OFFERS 'HOODWINK' VIEW-LIMITING DEVICE
A new view-limiting device for instrument training is available from Aviation Supplies and Academics. The Hoodwink is a collapsible hood that folds to the size of a change purse and easily fits in a pocket. To unfold, simply remove it from the carrying pouch and the metal frame springs open, making the hood ready for use. The small hood resembles a baseball hat with flaps on the side to limit the pilot's view. The Hoodwink is $16.95 and may be ordered from ASA or by calling 800/272-2359.
Note: Products listed have not been evaluated by ePilot editors unless otherwise noted. AOPA assumes no responsibility for products or services listed or for claims or actions by manufacturers or vendors.
My ePilot - Student Interest, Final Exam
Question: My instructor has warned me not to make low-level skidding turns when turning the base to final leg. Why?
Answer: The underlying characteristic of all skidded turns is excess yaw in the direction of the turn. They are uncoordinated maneuvers. Typically, the unnecessary yaw is pilot-induced, with too much rudder applied in the direction of turn. Both the deflected rudder and the inside wing point toward the ground when skidding. Excess yaw will tend to increase the angle of bank and rate of turn. These actions alter the character of the turn. Reacting incorrectly to a skidded turn by using opposite aileron to stop the increasing bank, followed by additional back-pressure to hold the nose up, pave the way for the classic unintentional spin. A quick glance at the inclinometer will show you the quality of the turn. Flying precisely and coordinated will not only keep your skills sharp, but your passengers will also appreciate it. For additional insight review the AOPA Air Safety Foundation Safety Advisor, Maneuvering Flight: Hazardous to Your Health .
Got a question for our technical services staff? E-mail to [email protected] or call the Pilot Information Center, 800/872-2672. Don't forget the online archive of "Final Exam" questions and answers, searchable by keyword or topic.