"I learned in Cessna 172s and was checking out in a Cessna 182 at a different airport. I went from flaps 10° to flaps 20° while turning base (as I have done many times in the 172) and the instructor chastised me saying never to extend flaps while banked. I’ve never heard this before. Have I been doing this wrong all along or is this flight instructor just misinformed?" — Casey C.
“While I, personally, have no issue with extending flaps while banked, the flight instructor isn’t misinformed. It’s really an issue of risk tolerance and probability.
Here’s the thinking behind your instructor’s admonishment: Whenever you extend (or retract) flaps, there’s a chance they will deploy asymmetrically. That means one flap will be extended farther than the other and act like an aileron. The plane would roll toward the less extended flap. An uncommanded roll close to the ground is dangerous. You’d have to counter with opposite aileron and retract the flaps back to a symmetrical position, or land with compromised controls.
That’s a risk whenever you extend flaps. The thinking of not doing it in a turn is that if the flap asymmetry caused a roll in the direction you were already banked, you might lose control of the airplane before you could recover from the roll. That would likely be fatal.
However … asymmetrical flap extension is exceedingly rare. Furthermore, you’d have a 50-percent chance the roll would be opposite your current bank and the bank would actually give you more time to recover. So the question is, if you feel the need to extend flaps to adjust your speed and configuration for landing, and can’t wait until rolling level, is it worth the tiny risk that you’ll have an unfavorable flap extension? For me, that’s a yes. Other pilots see it differently. You’ll have to decide for yourself.
The much more important lesson is to pay close attention to the airplane whenever you make any configuration change to see if it’s doing something unexpected. Be ready to counter that change and undo the thing you just did no matter what your flight attitude is.”
Are you okay with extending flaps while banked?