Flight hero/villain Ira Goldman in 2003. (Susan Walsh/AP)

A Denver-bound United Airlines flight was diverted Sunday after two passengers got into a tiff. The cause of their argument? The Knee Defender, a $22 device that prevents an airplane seat from reclining and was invented right here in the District. Ira Goldman used to travel 100,000 miles a year for his trade policy work, which wasn’t always comfortable for his 6’3” frame. So in 2003, the Mount Pleasant resident created the tiny gadgets, which connect to a tray table.

Is this the first Knee Defender fight you’ve heard about?
Look, the product has been on the market for 11 years, and if this had happened before, I would know about it. On every Knee Defender, it says, “Listen to the flight crew.” If a flight attendant says don’t use it, you don’t use it. No matter what you’re using on an airplane, don’t get into a fight over it.

How many have you sold?
A lot. It keeps the lights on for my company. And we don’t advertise. It’s all demand-driven. A lot of people use it because laptop screens can crack when people recline suddenly. Knee Defender protects against that. It’s been working for people for a long time. A lot of people say, “I didn’t want to buy it. But I had to.”

The Knee Defender

What else have you invented?
There’s the Scanner Bag. Guys don’t have pocketbooks or purses, so they put their cell phone, wallet and keys in a basket when they go through security, then they forget it when they run to a flight. So this is a luggage tag with a pouch that let’s you keep it all attached. I’m a typical inventor — I see a problem and I think about what it would take to solve the problem. I used to do that by writing legislation. Now I do it with products for consumers.

What else are you working on?
I have a new kind of leash for a dog, so people can ride a bike while walking a dog safely. But there isn’t a big market for that. And I came up with a little thing that attaches a cup holder to rolling luggage, so your cup of coffee won’t spill. I decided the market wasn’t there. It looks funny to see the cup swinging back and forth.

How did you start inventing?
My dad was in the toy business, and I invented some toys for him. Before I was born, he invented a water pistol with a knob, so you look like you’re aiming one way but then it shoots sideways. At one point, that was on Super Soakers. My brother invented Phlat Ball — you throw it like a Frisbee and it turns into a ball.

Any D.C.-specific problems you’re thinking about tackling?
I think all bike lanes should be in the center of the street, so you don’t need to worry about car doors.

More local news from Express:

‘Batman v Superman: Dawn of Justice’ will set some action in Washington, D.C.

Alphabet animal art invades Capitol Hill, Eastern Market and Southeast

Ferguson turmoil prompts cancellation of costumed “Cops and Robbers” race in D.C.