What do mean by “winging it,” where did this English-only expression come from, and why is it not a recommended tactic for most speakers? (I’ve done some work in Spanish and discovered there is no equivalent expression for “wing it.” So I have adapted the phrase to roughly translate as “don’t fly without all of your feathers.”)
 
You can tell when a speaker is “winging it” when they are obviously unprepared, speaking off the cuff, usually in a disorganized and not particularly impressive manner.There are folks who can speak in a fairly credible way when asked at the last minute, a treat when they are funny or exceptionally good, but usually it’s because they a) really know the topic well and b) have experience handling unplanned speaking situations.
 
The phrase “winging it” seems to have two different late 19th and early 20th century origins. One is attributed to the Indiana brothers who invented the airplane, Orville and Wilbur Wright. They did an extensive amount of testing on gliders before advancing to what we think of as an airplane today. On the gliders, a man would stand up and literally walk up and down on the wings of the aircraft to help balance it during flight, a feat that gained the name, “winging it.”  Another theory says that actors who had trouble remembering their lines in the late 1800s often relied on prompts from men and women off stage in the wings of the theater. Ill-prepared actors — or those who had to carry on when the prompter wasn’t on hand — became known as “winging it.”
 

I usually wave a rubber chicken in the air in my workshops to illustrate this phrase and discourage its practice. When you try to “wing it,” I contend, your presentation or speech will have as much flavor, as much substance and as much lasting appeal as Charlie, my much beloved and long-suffering rubber chicken. Not having a clear plan or the opportunity to practice can mean you accidentally leave out critical points, you stumble pronouncing words, and you muddle through with irrelevant or inaccurate statements.
 

The anti-winging-it solution? Ideally, give yourself ample time to clearly identify the two or three main points you want to get across in your remarks and build your message around them. Even if you receive a last minute request to speak, write down the two or three most critical ideas you want to get across, on a napkin if necessary. For best results, always practice aloud, out of order, in pieces, and time each element to be sure you’re not exceeding your scheduled allotment. For last-minute “winging it” situations, assume control as if you’d practiced. No one knows unless you tell them otherwise!
(Excerpted from Public Speaking for the Genius, For the Genius Press, due out in Spring 2014, by Anne B. Freedman. Copyright 2013.)