SAN FRANCISCO -- A Chinese professor who was seriously injured in the crash of Asiana Flight 214 has filed a $5 million lawsuit against the airline in U.S. District Court here, apparently the first foreign passenger to sue under an exemption in an international agreement that limits legal actions by foreigners.

The son of Zhengheng "Henry" Xie bought his father's round-trip ticket in California, giving Xie legal status in U.S. courts, according to Xie's lawyer.

Xie, a professor at the University of Shanghai, suffered vertebra fractures in the July 6 crash at San Francisco International Airport and remains in a body cast. He is being cared for as an outpatient at Stanford University Medical Center, said his Walnut Creed attorney, Michael Verna.

Xie would be barred from suing South Korea-based Asiana in U.S. courts because of an international treaty called the Montreal Convention that limits his legal settlement to no more than about $135,000 in China, where he is from, or South Korea, where Asiana is based. But the son's purchase of Xie's round-trip ticket in the United States represents one of five exceptions to the treaty, clearing the way for Xie's $5 million lawsuit filed in San Francisco, Verna said.

"Here we have an atypical situation, an exception to the Montreal Convention," Verna said. "While he is a resident of Shanghai and actually a Canadian citizen, since the ticket was purchased in the United States by his son, that gives him the option of suing Asiana in the United States. It's a technical, legal issue. But it's very significant."

Xie was seated near the middle of the plane and was flying by himself to visit family in California, including his son, who works for Apple (AAPL).

Verna's lawsuit was filed on behalf of Xie and his wife, Wei Song, and alleges that "Xie suffered, and continues to suffer, from extreme bodily and mental injuries and economic losses." Song suffered damages, according to the suit, because her husband before the crash "was able to and did perform all the duties of a husband, including assisting in maintaining the home, working to help support the family, and providing support and comfort to his wife."

The United States, China and South Korea are among the countries that signed the 1999 Montreal Convention that was designed to provide at least limited financial relief to passengers involved in airline disasters in foreign countries. Because of the treaty, injured passengers can file suit only in the country where they're from, where they bought their ticket or in accordance with three other factors that ultimately restrict the ability of foreign passengers to sue Asiana in the U.S.

Asiana has said it will not comment on lawsuits related to the crash, which killed three Chinese teenage girls and injured dozens of others.

In another post-crash development that continues to divide U.S. and foreign interests, the FAA is banning foreign pilots from landing side-by-side at SFO until Aug. 23, when a ground-based glide slope system that helps pilots line up correctly for landings is replaced. The system has been out since June because of construction to extend Runway 28 Right and Runway 28 Left, where the Asiana crash occurred.

The directive was part of an FAA advisory to foreign pilots last week suggesting they use their GPS navigation systems to line up while landing at SFO.

Neither the ban on side-by-side landings in clear weather, nor the advisory on using GPS, applies to U.S. pilots.

The FAA made the temporary changes after at least two foreign airliners, including an Asiana flight, aborted landings at SFO after the crash.

Contact Dan Nakaso at 408-271-3648. Follow him at Twitter.com/dannakaso.