SAN FRANCISCO (AP) — A Boeing 777 that crashed at San Francisco International Airport had inadequate warning systems to alert its crew about problems with air speed, Asiana Airlines said in a filing with regulators released on Monday.

However, the airline also acknowledged that its crew failed to monitor and maintain a safe airspeed before the July 6 crash and failed to abort the landing in time.

In its report to the National Transportation Safety Board, Asiana said the cockpit crew believed the auto throttle would keep the plane going fast enough to reach the runway — when in fact the auto throttle was effectively disengaged after the pilot idled it to avoid an unexplained climb earlier in the descent.

The airline said the plane should have been designed so the auto throttle would maintain the proper speed after the pilot put it in "hold mode."

Instead, the plane gave no indication that the plane's auto throttle had stopped maintaining the set air speed, and a low air speed alerting system came on too late for the pilots to avoid the crash, Asiana said.

"The flight crew believed that the autothrottle system would maintain the commanded airspeed through the final approach," Asiana said.

In its submission to the NTSB, Boeing said the airplane and all airplane systems were functioning as expected prior to impact and did not contribute to the crash.

"Boeing believes that the evidence supports the following conclusion: This accident occurred due to the flight crew's failure to monitor and control airspeed, thrust level and glide path on short final approach," the airplane manufacturer said.

Asiana also blamed air traffic controllers at the airport, saying they failed to respond to the flight crew's initial request to land and responded late to a second request. That increased the pilots' workload during the approach, Asiana said.

A call to airport spokesman Doug Yakel was not immediately returned.

The airliner slammed into a seawall at the end of a runway during final approach for landing. The impact ripped off the back of the plane, tossed out three flight attendants and their seats, and scattered pieces of the jet across the runway as it spun and skidded to a stop.

Coroner's officials concluded that one of three Chinese teens who died, Ye Meng Yuan, was run over and killed by a rescue vehicle as she lay on the tarmac after the crash.

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Pritchard reported from Los Angeles

BRANSON, Mo. (AP) — Federal officials are investigating why a Southwest Airlines flight that was supposed to land at Branson Airport in southwest Missouri, instead landed at another airport about 7 miles away that only had about half as much runway.

Southwest Airlines Flight 4013, carrying 124 passengers and five crew members, was scheduled to go from Chicago's Midway International Airport to Branson Airport, airline spokesman Brad Hawkins said Sunday in a statement. But the Boeing 737-700 landed at Taney County Airport, which is also known as M. Graham Clark Downtown Airport.

"The landing was uneventful, and all customers and crew are safe," Hawkins said.

Hawkins did not have information on why the plane went to the wrong airport. Federal Aviation Administration spokesman Tony Molinaro says the agency is investigating the incident.

It's the second time in less than two months that a large jet has landed at the wrong airport.

In November, a Boeing 747 that was supposed to deliver parts to McConnell Air Force Base in Wichita, Kan., landed 9 miles north at Col. James Jabara Airport. That plane was flown by a two-person crew and had no passengers.

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In this photo provided by Jared Rosenstein, a Southwest Airlines plane whose nose gear collapsed as  …

The website for M. Graham Clark Airport says its longest runway is 3,738 feet. Branson Airport's website says its runway is 7,140 feet long.

"The landing was really abrupt and the pilot applied the brakes really strongly," Dallas attorney Scott Schieffer, who was on the flight, told WFAA-TV. "You could hear it and you could certainly feel it."

Flight tracking website Flightaware.com said the Southwest flight landed at 6:11 p.m. Sunday. It was partly cloudy and in the high 50s in Branson at that time.

"Our ground crew from the Branson airport arrived at the airport to take care of our customers and their baggage," Hawkins said.

Flight 4013 had been scheduled to go from Branson to Dallas' Love Field. Hawkins said a plane was flown in specifically to Branson Airport around 10 p.m. to take the passengers and crew to Dallas, which flightaware.com showed landed at 11:42 p.m.

Hawkins told The Associated Press the aircraft at M. Graham Clark Downtown Airport will be able to take off on the smaller runway, and Southwest expects to fly it out "as early as (Monday) morning."

The Taney County Sheriff's Office referred all calls to M. Graham Clark Downtown Airport. Messages left for comment from M. Graham Clark Downtown Airport were not immediately returned.