As investigators continue to pore over flight data, cockpit recorders and information from pilot interviews, several questions remain about what exactly led to the fatal crash of Asiana Airlines Flight 214 last week in San Francisco.

Here are a few things that we do know about what happened that day:

1. The plane was flying too low and too slowly before it crashed

The Boeing 777 was traveling at speeds "significantly below" the target landing speed of 137 knots, or 157 mph, according to National Transportation Safety Board chief Deborah Hersman. Seven seconds before impact, someone in the cockpit asked for more speed after apparently noticing that the jet was flying far slower than its recommended landing speed. A few seconds later, the yoke began to vibrate violently, an automatic warning telling the pilot the plane is losing lift and in imminent danger of an aerodynamic stall. At 1½ seconds before impact, there was a command to abort the landing. Almost immediately after that order was issued, the air traffic controller guiding the plane heard the crash.

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A chart showing the descent of Asiana Airlines Flight 214 seconds before it crashed. (CBC)

2. Parts of the plane were found in the water

During the crash landing, the plane clipped its landing gear and then its tail on a rocky seawall just short the runway. Witnesses of the crash, who had seen the disaster from a distance, told CBC News it looked like the airplane was missing its tail.

Two days later, Hersman said that a "significant piece" of the tail of the aircraft was in the water, and other plane parts were visible at low tide. The lower portion of the plane's tail cone was found in rocks inside a seawall, and other debris from the seawall was found hundreds of metres along the runway.

3. Two passengers were killed, 180 others were injured

Of the 307 passengers on board, two were killed in the crash — Ye Mengyuan and Wang Linjia, 16-year-old students from China who were planning to visit U.S. universities. One of the bodies was found on the runway near where the plane's tail broke off upon impact, while the other was found on the left side of the aircraft about 30 feet away from where the Boeing 777 came to rest after it skidded down the tarmac and not far from an emergency slide. There is speculation that one of the victims was killed by being run over by an emergency vehicle after the crash.

One hundred and eighty passengers were taken to hospital, some with serious injuries. Two were paralyzed, and two others suffered road-rash-like injuries suggesting they were dragged. Doctors also reported seeing abdominal and orthopedic injuries and head trauma. Passengers with severe abdominal injuries and spinal fractures appear to have suffered them by being thrown forward and back while restrained by seat belts. San Francisco General Hospital’s Chief of Surgery Margaret Knudson said everybody who could talk to staff told her they were in the back of the plane.

Two flight attendants working in the back of the plane were also ejected and survived. Both women were found on the runway, amid debris.

4. The pilots had more than 20,000 hours of flying experience combined — but less than 3,500 on the Boeing 777

The pilot at the controls was only about halfway through his training on the Boeing 777, and it was his first time landing that type of aircraft at the San Francisco airport. Asiana spokeswoman Lee Hyomin said that Lee Gang-guk had nearly 10,000 hours flying other planes but only 43 on the 777, a plane she said he still was getting used to flying.

The co-pilot, identified as Lee Jeong-Min, was on his first trip as a flight instructor. Lee had about 12,390 hours of flying experience, including 3,220 hours on the 777, according to the Ministry of Land, Infrastructure and Transport in South Korea. He was the deputy pilot, tasked with helping Lee Gang-guk get accustomed to the 777, according to Asiana Airlines. Two other pilots were aboard, with teams rotating at the controls.

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An aerial view of the San Francisco runway after the crash. (CBC )

With files from The Associated Press