TALESPINNERS - February, 2002

Mixed Up Attitude
by Terry Taylor

Say what? In order to illustrate my point in this article, let's pick up when I was returning from Oshkosh last summer, in which you read about that experience a couple of months ago. The weather was deteriorating and I was trying to request an IFR clearance from Indy Center, and finally got one from Cincinnati Approach Control. You remember the drill now, right? OK, I was on vectors for the VOR-B approach and in total IMC with rain. The Cardinal autopilot was on Heading Select and Altitude Hold. The rain was steady and this was my first experience in real IMC in this bird. Single pilot IFR flying is pretty tough without an autopilot, so I was using all of my resources at the time.

Cincy Approach gave me a vector to roll out on the VOR approach about 3 miles outside of the FAF (Final Approach Fix). I was using the Heading Select function of the autopilot and I rolled out past the final approach course. I turned back and then overshot that heading. Basically, I didn't have any good experience to know what lead points to use to roll the aircraft out on a course using the autopilot. The slower speed of the aircraft, and faster turn rate made the heading turn faster than I was used to. Getting closer to the FAF, I clicked off the autopilot and started hand flying the airplane. One of the lessons learned from years and years of experience - when the automation isn't doing what you want it to do, get rid of it and go back to basic aircraft flying. That's what I did.

While now hand flying the VOR approach, I noticed that I had a tendency to roll the wrong way out of a turn. From straight and level, I knew to make a small left or right turn to move the yoke left or right. Hey, that's easy. However, when I wanted to roll out of a turn, especially one that I had held for more than a few seconds, I had the tendency to roll out the wrong way. Yes, I know to roll out of a left turn I needed to turn the yoke to the right, but I was reading instruments at the time and I would start my rollout to the left. I did this several times, and in the heat of battle flying a non-precision approach in real weather for the first time by myself, I just kissed this off to DSM (Dumb Stupid/Scared Mistakes).

Over time, I knew I needed to practice instruments under the hood or in real weather, so Mike Franzago and I went out and did a few ILS' into Lunken. I noticed that I had the same tendency to rollout of turns the wrong way. Now wait a minute! What's going on here?

Looking at the Cardinal attitude indicator, I noticed that the scale around the indicator was moving left and right when I made a turn, and not the ball itself. In other words, the ball with the pointer at the top was "fixed" to the attitude of the aircraft. Now, stay with me as this gets a little confusing, thus as you will see why I was so confused. When I would make a 30 degree left turn in the Cardinal, the pointer would move to the LEFT 30 degree index on the scale. Sounds reasonable. In actuality, the outer scale was moving to the right as far as what I was seeing as I turned the aircraft. The gyro was actually connected to the outer scale and it turned or tilted so that it's center point (straight up)stayed level (or perpendicular depending how you view this) with the outside horizon.

Notice the inner and outer pointer positions on the Cardinal
attitude indicator for a left turn.

The next time I was in the B-767, I wanted to make a few turns and see the attitude presentation on its attitude indicator. What I am looking at here is nothing more than a small TV set (known as a CRT, cathode ray tube) . All of the information goes through a symbol generator (another black box) to portray in color the horizon and attitude of the aircraft. If you are familiar with Flight Directors, the Bank and Pitch Steering bars are presented there in magenta as well. The gyro for the attitude indicator comes from one of the Inertial Reference Units (IRU). As an aside, this gyro is really a laser gyro, a glorified light spinning around in a box. Smarty pants stuff! You give the IRU your Lat/Long while parked, and it will take you anywhere in the world without any references from the ground such as VOR or DME or GPS.I noticed that when I made a left turn in the 767, the pointer went to the right.

Notice the different positions of the inner and outer pointers
of a B-767 attitude indicator.

What gives! Looking closer, I saw that the ball was fixed to level flight, or to the horizon, and that the scale above ball was fixed to the aircraft. This is exactly OPPOSITE to what the Cardinal does. So, to summarize, the Cardinal outer scale stays level with the outside horizon and moves physically when the airplane turns. The gyro is attached to the scale, thus the scale moves. The ball on the Cardinal is fixed to the airplane frame and does not move as the airplane rolls left and right, but appears to move since the scale is moving instead. The 767, as an opposite, has the outer scale fixed to the airplane frame, and the ball stays level with the horizon. No wonder I was trying to roll out of turns the wrong way on the Cardinal. I had flown these CRT displays in commercial aircraft over 20 years and I had become a creature of habit. In the 767, I had subconsciously learned to roll out of a turn TOWARDS the pointer at the top of the ball. That would make rollouts in the Cardinal the wrong way. Thus, I solved my problem and I now see why I had the tendency to roll the wrong way out of turns in the Cardinal. I'm not sure knowing this will cure any tendencies to correct this problem because I'm more of a creature of habit, but I will think more about it in the future. Notice in both photos, that the airplane is in a left turn. Also, in the near future, I plan to add an electric attitude indicator to the Cardinal.

Even a brand new vacuum pump is susceptible to failure in the first minute of use. You never know when it is going to be a problem. I've looked at standby vacuum systems, but I've come to realize that the electric attitude indicator is a much better solution, albeit at a higher cost. This doesn't obviate partial panel practice. You have to remember that we do all this for fun and enjoyment. To me, flying instruments is one of the most fun things that I like to do in airplanes. As a young Air Force T-38 instructor pilot (IP), I loved to get in the back seat "under the bag" and fly high TACAN penetrations and non-precision approaches, plus ILS and GCA approaches with another IP in the front seat. In the Cardinal, I realize that I will need to be proficient flying cross panel using the new electric attitude indicator, plus some partial panel experience. That's a challenge, and to me these challenges are fun. I'll need to make sure that the new electric attitude indicator is one that the scale moves in turns, and not the ball. It wouldn't do to have one attitude indicator point one way, and the other indicator point the other way for a given turn. That would be really confusing.

So if you see a Cardinal out flying instrument procedures someday, and it rolls upside down, you'll know why! (and who it is).

MEMBERS FLYING AIRCRAFT AS OF FEBRUARY 2002

Non-flying members, call your favorite pilot to see if he will be attending the Fly-out and if he will have a seat for you to ride along.