The house went up in 1982, the growing family moved in 23 years later, and the airplane crashed into it a week ago. All the while, the airport had been just down the road.

The tragedy of six deaths on Drop Forge Lane in Gaithersburg will be blamed on someone or something — an error or a defect that caused the plane to go astray and plunge down on a quiet cul-de-sac — but its root cause may lie in the unfettered expansion that has put some airport runways cheek to jowl with suburban development.

The four-bedroom house at 19733 Drop Forge Lane, with a fireplace, two-car garage and deck in the back, is a bit more than a half-mile from the end of the runway at the Montgomery County Airpark.

The private jet whose crash set that house ablaze last Monday killed all three on board and a woman who huddled in her second-floor bathroom, desperate to protect her infant and toddler son.

“Yes, the airpark was there first, but now we’re here, too, and this is dangerous,” said Becky Trupp, who moved this year to the Hunters Woods development where the plane crashed. “We have to find a way to coexist, and if we can’t coexist, I think that the safety of a community should take precedence over a hobby.”

Most accidents at smaller suburban airports are minor miscues that do not cause injuries.

For 30 years, people who live in the neighborhoods that surround the Montgomery County Airpark have been fearful something might happen to endanger them.

For instance, they worried after a single-seat plane crashed 100 feet from the runway, and when a single-engine plane with four aboard crashed in someone’s back yard two miles north of the airpark, and when two people died when a twin-engine plane hit a cornfield a few hundred yards short of the runway.

All three of those accidents happened three decades ago. A headline in The Washington Post in the aftermath read “Some critics say it’s an accident just waiting to happen.”

The 1984 article quoted one man who lived nearby: “It’s inevitable that a plane will fall out of the sky.”

Until a week ago, however, nothing so nightmarish as what they envisioned had occurred. Since 1983, there have been 29 airplane crashes at or near the airpark, fewer than one a year. Only four resulted in injuries to the pilot or passengers. In three of them — in 1990, 1985 and 1983 — people on board died. Almost a third of the crashes involved novice pilots working with flight instructors, the sort that aviation investigators refer to as “Oh, s---” accidents that are more likely to cause embarrassment than injury.

“There are a couple of flight schools there. You’re getting buzzed by people learning how to fly,” Trupp said. “They fly quite low. They feel like they’re right at the tops of the trees sometimes.”

The number of accidents puts the airpark in Gaithersburg about on par with three other regional airports that handle roughly the same amount of traffic in private airplanes.

Several homes were damaged Monday morning when a plane crashed into a house near Drop Forge Lane off Snouffer School Road in Gaithersburg, Md. (Dan Morse/The Washington Post)

The busier airport in Frederick has averaged a fraction more than one accident a year. Both Leesburg and Manassas experience fewer than one per year.

The number of small-plane fatalities nationwide last year, 379 deaths, was the lowest in decades.

About 110 times since 2000, a small plane has crashed into a building or house, most often near an airport. Those crashes have resulted in more than 120 fatalities, almost all of them the deaths of pilots and passengers.

The highest number of people killed on the ground came seven years ago when a plane owned by NASCAR destroyed two homes in Sanford, Fla.

That number — three dead — was matched last week when Marie Gemmell, 36, huddled in a second-floor bathroom in a futile effort to save herself and two of her children — 3-year-old Cole and 6-week-old Devin — as a blaze fired by jet fuel raced through their home.

Pilot and business executive Michael Rosenberg, 66, and two colleagues aboard the plane — David Hartman, 52, and Chijioke Ogbuka, 31 — also were killed in the crash.

Suburban growth

There wasn’t all that much around in 1960 when the new airport opened 23 miles north of downtown Washington and three miles northeast of Gaithersburg, then a town of 3,847 people.

The county had zoned 137 acres next to it for industrial development and 135 acres nearby for residential development, but in those days there were acres and acres of undeveloped fields surrounding the new airstrip.

The airport hasn’t grown much, though the runway is 1,000 feet longer now, but the rest of the landscape has changed dramatically. Between 1970 and 1990, Gaithersburg grew almost fivefold, and the population has reached 60,000.

That growth has enveloped the airpark.

There is a map that tells the story. It is an aviation chart of the Washington region, encompassing dozens of airports that range from the mega-big such as Dulles International and Baltimore-Washington International Marshall airports to unpaved landing strips.

Outside of the District, it shades the most densely populated areas in yellow.

Three other airports similar in size to the airpark — in Frederick, Leesburg and Manassas — are just beyond the fringes of the yellow zone. The Montgomery airpark is virtually surrounded by yellow.

“When I came there, I don’t think there were as many houses there as there are now,” recalled Richard C. Bartel, who served as the airport’s manager from 1983 to 1991 and then went on to spend eight years as a crash investigator for the Federal Aviation Administration. “The airport hasn’t really changed a whole lot. It’s the neighborhood that’s changed.”

Life in Hunters Woods

Just to the north of the runway, a brand-new development had been built the year before Bartel arrived, so new that not all of the 448 houses had yet been sold.

It was named for the tract of land that once sat largely vacant: Hunters Woods.

Like so much of suburbia, it was a warren of looping streets and cul-de-sacs. Blue Smoke Drive, Ridge Heights Drive, Alliston Hollow Way, Drop Forge Lane.

Decades before Ken and Marie Gemmell bought 19733 Drop Forge in 2005, or Becky Trupp moved into 9 Alliston Hollow in January, Bartel had a problem on his hands. The people who had moved into pricey new homes near the airport weren’t happy with the noise or the threat of low-flying planes.

“There was always the possibility of a crash,” he said. “It concerned me for many reasons, for noise abatement and safety.”

While the county’s Revenue Authority, which runs the airport, cautioned in 1984 that people should consider proximity to the airport when buying a home, Bartel said he took steps to protect the new development.

“We adjusted the official traffic pattern so that it would channel traffic over Snouffer School Road,” he said.

Much like airplanes coming into Reagan National Airport are supposed to follow the path of the Potomac River, planes taking off to the north from the airpark are supposed to angle to the right and fly over the road.

If you look to the left as you drive north on Snouffer School Road, you will see the back deck of the house bought by Ken and Marie Gemmell.

Planes planning to land at the airpark aren’t bound by the same regulation.

“Arrivals generally came in over the road, but some would come straight in,” Bartel said.

“Straight in” was what pilot Michael Rosenberg was flying when he crashed last Monday morning, and experts speculate that it may explain what went wrong.

Seconds before he crashed, in his next-to-last radio transmission to other pilots flying in the area, Rosenberg said he was headed for the airpark’s runway 14.

“Montgomery traffic, 100 Echo Quebec is 3 [miles] out, straight in [toward] 1-4,” he said, according to a transcript of the air traffic transmissions.

Straight in has a particular meaning to pilots who frequent uncontrolled airports such as the Montgomery airpark. Without the guidance of an air traffic controller, in most cases a plane will fly above the landing strip and then double back for a safe distance before turning again to make a final approach.

In a straight-in approach, the pilot dispenses with that exercise and flies directly toward the runway.

It carries a bit more risk, but there is also risk in making a circular loop in the high-performance twin-engine jet that Rosenberg was piloting.

“That doesn’t mean that straight in is a line down the runway, straight in could be any direction, 30 degrees left or right,” Bartel said.

Speculation abounds

The National Transportation Safety Board’s investigative report, expected sometime next year, is all but certain to pinpoint what went wrong. But the data from recorders on the plane and the observations of Bartel, another retired FAA investigator and a former air traffic controller suggest a likely answer.

In the last 20 seconds of flight, the NTSB said based on preliminary data from the recorders, the plane slowed to below a safe speed and an automatically triggered recording warned Rosenberg that his plane was on the verge of an aerodynamic stall. That meant its nose was up and tail was down to the point where air flow above the wing was insufficient to keep the plane aloft.

The experts speculate that he had drifted off the centerline path to the runway, banked hard to the left to correct that and didn’t ramp up the plane’s energy enough to compensate for the reduced speed.

“He overshot the centerline of the approach leg, banked too sharply, losing lift, and crashed directly down,” said Glenn Groh, a former Air Force tower controller who is not involved with the investigation but evaluated accounts.

Directly down was Hunters Woods. And the plane was on the outer fringe of the traffic pattern Bartel created to protect the neighborhood 30 years ago.

Becky Trupp sits on her back deck often enough to recognize which planes stick to the correct traffic pattern and which don’t.

“It’s the exception to the rule that they are doing what they’re supposed to be doing,” she said.

Did she recognize that the airpark might pose a risk before she bought her home?

“I didn’t, and that’s shame on me,” she said. “I knew the airport was there. I just didn’t know that those planes flew over the neighborhood like they do. I had no idea.”

She lives two blocks from where Rosenberg went down.

“If he had stayed airborne for a little bit longer, it could have been my house,” she said.