The company had been moved from the United States because of financial incentives available in Canada that would make aircraft certification affordable.

He trained as a pilot in Florida at Phoenix East Aviation, Inc. and got his commercial aircraft certification in 2008.

The change was approved by the F.A.A.'s office of aircraft certification.

Elizabeth Erickson, the agency's director of aircraft certification, said in a telephone interview, "Our concern has been heightened in this area."

Her father retired as the director of aircraft certification for the Aerospace Industries Association of America, an industry and lobbying group in Washington.

"This insulation sits in the airplane very innocently most of the time," said Beth Erickson, director for aircraft certification of the aviation agency.

Ability to quickly self damp when the stick is briefly displaced is one of the many criteria for general aircraft certification.

"There is a level of safety afforded by 180 minutes today," Tom McSweeny, the agency's associate administrator for aircraft certification, said in an interview.

The Federal Aviation Administration's director of aircraft certification, Elizabeth Erickson, said today that "there is no immediate safety problem."

Only multi-engine, fixed-wing aircraft with special crew and aircraft certification can operate at London City Airport.