But when it came to settling on a career, he decided there was not enough real piloting involved. “We were told, ‘Nobody flies above 10,000 feet, they’re all on autopilot. You’re a glorified backup,’” he recalled. “Whatever romance was left in commercial aviation, the jet engine killed.”

He was not interested in stunt flying or becoming a military pilot, so he abandoned aviation and found a job managing a branch of a courier company in Silicon Valley. Jobs at a consulting firm that handled transportation planning issues and at another trucking firm followed.

Then it was on to law school at Boston University and a summer job as a volunteer law clerk, drafting opinions for administrative law judges from the National Transportation Safety Board. “None of the judges were pilots,” he said. “I understood the facts better than they did, no offense. They said they wanted to hire me on a paid basis during law school.” So they did, and also after he finished law school.

The slowest part of a conversation with Mr. Avedisian is the tell-us-all-about-it part, because he will not discuss details of his idea for the subway while the contest is still going on.

The transit agency said he was a finalist in a category called “Rapidly Deploy Modernized Subway Cars to the Subway System.” (The other categories involve modernizing the antiquated signal system and improving the communications infrastructure.)

The transit authority said Mr. Avedisian had proposed “adding up to four cars to trains currently in operation to increase both train capacity and passenger comfort.” The agency said Mr. Avedisian’s longer trains would stop at every station, but not every car would open. “Some cars at the front and back of a train will not platform at every station,” the authority said, “but generally will platform at alternating stations.”

In plainer terms, using an existing 10-car train as an example, the first four cars would open at one station, leaving the last four beyond the platform with the doors closed. At the next station, the train would in effect overshoot the platform, allowing the last four cars to reach the platform and open while the first four stayed shut. Six cars in the middle would open on the platform at every stop.