Just out of curiosity, what makes it tough?
What makes it tough is many applicants do not have both sufficient mastery of the material and the teaching skills to be able to teach the material to someone who doesn't know it already.
Is it the required precision of the flying
No. Applicants for CFI have already demonstrated the required level of flying precision on their Commercial Pilot practical test. The trick at the CFI stage is to be able to talk about what they are doing while they are doing it. Many folks can fly it or talk it, but not both at the same time. The other big problem in flight is being able to determine just what the "student" (i.e., the examiner pretending to be a student) is doing wrong on a maneuver and provide accurate input to the "student" so the "student" can fix the problem. The last issue is maintaining situational awareness and outside visual scanning for traffic while flying and talking through the maneuvers.
or does the examiner pull idiotic stunts such as students might do and which require the CFI to exercise superhuman flying skills to avoid the both of them going down in flames?
No. That would be too close to the edge for safety. The examiner will bumble some maneuvers to see if the CFI applicant picks up what's wrong (e.g., insufficient or overcontrolled rudder during a chandelle) and teaches the "student" how to correct the "error."
They may also do something near the ground during landing to see if the instructor applicant takes control correctly and in a timely manner. For example, the "student" might overcontrol pitch in the flare and then move the yoke forward to push the nose down. The instructor applicant should be guarding the yoke to prevent this from going so far as to hit nosewheel first or with too great a sink rate -- just as s/he will have to do with primary students later on.
And I cannot overemphasize that the CFI ride is primarily about teaching, not flying. You will be judged more on your ability to impart learning to your student than on any demonstration of your own pilot skills. The Aviation Instructor's Handbook book is rather dry, and (considering that it’s supposed to be prepared by professionals who really know about teaching) not all that easy to learn from. However, the important data are there, and you’d best learn not only to parrot them, but to understand what they mean and apply them when you teach (and if you don’t recognize these “levels of learning” you’re not ready yet). You will have to be able to read the student’s mind to find out whether he’s really learned the material or not, and if not, WHY not. Then you must be able to figure out how to get past whatever barrier to understanding exists in that student’s mind. You’ll find that there are as many successful techniques as there are students, but there may only be one of those many that works for any one particular student. Being able to hit on one that will work quickly, before the student becomes discouraged, is the toughest part of flight instructing.
How to work through this? Get with some successful teachers, not necessarily pilots. I’m talking about someone you know who’s an experienced high school teacher, one that the kids remember long after graduation as the highlight of their experience. Talk about teaching and learning with this person. You might also consider some basic education courses at the local college.
Finally, here are a few points I put together to get your mind right for the initial CFI checkride:
1. You are a teacher, not a pilot. How you teach is far more important than how you fly the plane. It doesn't matter if you slightly screw up a maneuver, as long as you identify the screw-up as it happens, talk about why it happened, and then how to do it right.
2. Don't rush into any answers. When asked questions, show the examiner where the answer is written -- you're showing how to teach a student, not demonstrating your own superior knowledge. That means you should know COLD where to find the answers -- if asked about the red/green/white tower light gun signals, it shouldn't take you more than a few seconds to get to the right page in the AIM. And you should know instantly whether an answer to an FAR question is in Part 61 or Part 91 (HINT: If the rule applies no matter who's flying the plane, it's in 91. If not, it's in 61.)
3. Be relaxed and organized. When asked a to teach an item, take a moment to gather your thoughts and draw out any blackboard diagrams or itemized lists for the lesson. You're not on "Jeopardy" -- there's no one gonna beat you to the buzzer and steal your $200 prize.
4. Inventory your stuff before you go to the meet -- the checklist in the PTS is a good tool. Make sure you have all the source materials to teach as well as answer all the questions in the PTS.
5. Typically, during the oral, the examiner will jump on one topic and continue asking questions until you run out of answers. In the Air Force, we called this game "Stump the Dummy." As the questioner knows more than the questionee about the topic he selected (which is why the questioner selected it), the final outcome (the dummy is stumped) is never in doubt. The critical elements are how far the dummy can get before being stumped, and how he handles the situation -- straight knowledge, clear explanations, use of the book when appropriate or necessary, and no BS or tap-dancing when finally stumped.
6. Expect a long, grueling session. You're being given the authority to release others into the sky without anyone else's oversight. They want to make damn sure you can make good decisions in that respect. For that reason, I think the initial CFI is the most significant ride you'll ever take.
Good luck,
Ron Levy
CFI since 1973
My DPE charges $200.
And another tip - the most misunderstood control is a rudder 