THE TIMELINE of an aviation career, for some of us, is punctuated with dark occurrences. Furloughs, rejection letters, bankruptcies. And now, sigh, I’ve lost my beloved calculator.

I bought the thing 23 years ago, if I remember right, at the old Osco store on Highland Avenue near Davis Square. It was your basic flip-top model, dual solar and battery, with fat buttons and an oversized screen for better low-light viewing. I paid about four dollars for it.

When you own anything for 23 years, you grow fond of it. //

You can see the calculator in the picture below, taken in 1998. No, that’s not a U-boat circa 1944; it’s the flight engineer’s station of a Douglas DC-8. This was my office for about four years, shuttling cargo to and from Europe and across the U.S. The calculator is on the ledge, lower left. Notice it has an orange sticker on its case. I added the sticker for the same reason that I use a bright red bumper on my iPhone: to keep me from leaving it behind. So much for bright ideas, literally.

The calculator was a necessary instrument on the ancient Douglas. The weight, balance, and fuel calculations were all done by hand. It was simple arithmetic, but these were big, six-digit numbers. Not so much on the 767. It’s the dispatchers, loaders and planners who do all the serious number-crunching. They upload the results to us and we plug them in. About the only things we calculate manually are the waypoint crossing times and maybe the start/end times of our crew rest breaks. This is hardly anything technical; they’re just figures of convenience jotted down in the margins of the flight plan, requiring nothing more than adding or subtracting a few simple numbers.