Editor's Log

October 2001 Issue




Weighty Matters

Think again if you think guessing someone’s weight is close enough

It was time to introduce a non-pilot friend to aerobatics. He had been expressing interest for some time, and finally our schedules meshed and we headed out to the airport to strap on some unusual attitudes.

He had flown in the Citabria once before, on a flight where we did some spirited maneuvering, but no aerobatics. I like to introduce neophytes this way because it allows them to get used to the motion and I can avoid having to wash out the interior of the airplane afterward.

Before that first flight, we were waiting for the fuel truck and I asked him how much he weighed. “A buck eighty.” I ran the weight and balance and found we could carry full fuel and still be comfortably within limits.

On the next flight a few weeks later, I dipped the tanks and found 20 gallons. I ran his weight, his parachute, myself and my chute. We were slightly into the normal category, but by the time we burned off some fuel getting to the practice area we’d be right within the aft limit of the aerobatic envelope.

We cleared the area and my passenger asked for a loop. Because it was his first trip, I decided to do one maneuver at a time and give him a chance to stop me if he started feeling uncomfortable.

The first one was a little sloppy, which I attributed to the relatively light 2-g entry pull. I cranked in just over 3 g’s on the next entry and it really fell apart. The airplane bucked and buffeted and it was difficult to complete the maneuver with any semblance of order. It had been two weeks since I’d flown any loops, but I had a hard time believing my technique had deteriorated so badly in that time.

The third entry was clean, the pull brisk and the loop was clean until we were about 30 degrees short of inverted. At that point the airplane decided to act up again, with the stall horn bleating and an unusual airframe buffeting I’d never felt before.

Duh. At long last the light in my brain clicked on.

I pointed to some isolated storms north of our position and said I didn’t like the way they were moving in. I cut the flight short.

As we sat around the lounge afterward, I made some self-deprecating comment about how sloppy the maneuvers had been. As if on cue, my friend said, “Yeah, well, last time we flew and you asked me what I weighed I just guessed. I think I told you about 10 pounds less than what my scale says.”

After he left, I re-ran the weight and balance, using his actual weight. We had been a half-inch behind the aft limit for aerobatics, although well within the normal category.

Asking a passenger’s weight (or asking to weigh the baggage) can be embarrassing. They may flatter themselves with their answer. I was lucky this time and learned a valuable lesson: Trust, but verify.


-Ken Ibold