Goldman has invented the Knee Defender, a beeper-sized block of plastic that lets long-limbed passengers prevent the seat in front of them from reclining.
The gadget went on sale about a month ago on the Internet for $10, but aviation officials worry that it will spark disagreements at 30,000 feet.
Goldman, who's 6-foot-4, said he didn't invent Knee Defender so fliers would be able to "hog scarce space," but rather for the physical well-being of tall travelers like himself.
"If I hadn't been bashed in the knees over and over again, this wouldn't have been invented," said Goldman, who estimated that nearly 1,000 Knee Defenders have been ordered. At the very least, he said the device could be a useful "early warning system" for long-legged fliers or people using laptops, enabling them to ask the passenger in front not to recline.
While the Federal Aviation Administration discourages people from using anything that would "alter the performance of any part of an airplane," spokeswoman Alison Duquette said it would be up to individual airlines to prohibit the Knee Defender.
Northwest Airlines already says it will ban it from all flights. Other carriers, such as American Airlines and Delta Air Lines, acknowledged concerns about safety — not to mention the comfort of passengers who want to recline — but are still figuring out what to do.
The safety concerns stem from the design, because the Knee Defender works only when the tray table is down. The hard plastic block, which has an inch-wide groove down the middle, fits around the arm of a tray table and acts as a barrier to the seat's backward movement.
"We have tested this product on several seat types and find that when installed, should someone try to force the seat to recline, the tray table assembly can break," said Mary Stanik, a Northwest spokeswoman. "If the seat is damaged, including the tray table, in flight, it may adversely affect passenger evacuation in the event of an emergency."
Goldman, a 50-year-old Washington, D.C., resident, said he would stop selling the product if the airlines prove it unsafe, but so far he's unmoved by their arguments.
Kevin Gross of San Francisco, who ordered a Knee Defender but hasn't yet used it, said he would immediately remove the device if asked to by a passenger or flight attendant. But Gross is betting it'll go undetected in most cases, since travelers will just assume the seat is busted and not make a fuss.
Don't count on 50-year-old Dan Hammer of White Plains, N.Y., to be so docile.
"If I saw somebody that put the Knee Defender on the seat behind me so that I can't go back, I'll be very upset," he said.