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(NBC News) The pilot whose Boeing 777 crashed last summer at the San Francisco airport told investigators he was "very concerned" about attempting a visual approach without the runway's instrument landing aids, which were out of service because of construction.

Lee Kang Kuk, a 46-year-old pilot who was landing the big jet for his first time at San Francisco, "stated it was very difficult to perform a visual approach with a heavy airplane."

The jet crash-landed after approaching too low and slow in an accident that killed three people and injured more than 200, according to the National Transportation Safety Board.

The investigative report was released at the start of a daylong NTSB hearing.

The hearing was called to answer lingering questions about the crash, not to conclude exactly what went wrong.

Read More: http://nbcnews.to/18mujrQ