How do you fix a flying elbow?

Cut68,

Read this thread on how to practice, http://thesandtrap.com/t/54840/simple-specific-slow-short-and-success-the-five-s-s-of-great-practice#post_668894

As for flying elbow and chicken wing, there are some simple drills with a ball placed between your forearms you can try (search this forum).  I find it best to use a very soft, nerf-type ball for those drills.  A stiffer ball requires too much tension to hold and makes it harder to practice.

Also, in line with the above videos, get the feeling in your swing of extending your arms away from you as you get to the top of the back swing.  I sometimes think of pushing down on my left thumb with my right palm (righty).  Do this in a relaxed manner without increasing arm tension.

Lastly, don't let a $150 per hour guy mess with you.  You've got down to an 11 handicap, so you must be doing something right.  Sounds like he was fishing for business and got into your head.  Jack Nicklaus had a flying elbow and Lee Westwood has a bit of a chicken wing at impact.  Those two are pretty good golfers.

It's Golfing Machine lingo.  From Erik's List here are some Golfing Machine terms, there is a lot more.  Written almost an encyclopedia for all the possible variations of how to make a golf swing.

Motions

Basic Motion = Clubhead goes two feet back and two feet through (kinda like a chip)
Acquired Motion = Clubhead taken back until the right forearm is parallel with the ground and then parallel with the ground again on the follow through ("9-3").
Total Motion = Full golf swing.

Accumulators in the Golf Swing
1: A bent right elbow
2: Leading (top) wrist cock
3: Angle between shaft and lead forearm (expressed as rotation about that lead forearm)
4: Angle between lead arm and shoulders
Each accumulator has a corresponding pressure point.

Pressure Points in the Golf Swing
1: The heel of the bottom hand where it touches the top hand or grip
2: The last three fingers of the top hand
3: The first joint of the bottom hand index finger where it touches the grip
4: Lead armpit (or where the lead arm touches the chest)
5: Trailing armpit*
* Stack and Tilt and MORAD people add this one. There's no corresponding accumulator but it lets them talk about the trailing elbow separating (or not) from the chest.

Shaft and Elbow Plane
In a one-plane swing the head and hands will follow or stay between two lines: the shaft plane and the elbow plane. Both can be seen here in green and red . Hands follow the shaft plane until the right elbow begins folding, at which point they move up to the elbow plane. Impact is somewhere between the two and the clubhead and hands should exit the far side of the body

Here I am working on extensor action through feeling more pressure point #1

Careful on this one.  I was focusing too much on this and my swing got too shallow at the top of the backswing.  I have been working on breaking that habit by feeling that the elbows are closer together at the top (P4) by extending my arms away from my body (Thanks mvmac).  For me, it may be that I don't have all my flexibility back in my right shoulder do to rotator cuff surgery.  It may work for others.