TASK DEFINITION: Generate a correct and concise answer for the question based on the words in the context.
PROBLEM: Context : The 2007 Balad aircraft crash was a 9 January 2007 airplane incident involving an Antonov An-26 airliner, which crashed while attempting to land at the Joint Base Balad in Balad, Iraq, which was at that time operated by the United States Air Force. 
Question : On what date did 2007 Balad aircraft crash occur?

SOLUTION: 9 January 2007

PROBLEM: Context : Robert Ledley died of Alzheimer's disease in Kensington, Maryland, USA on July 24, 2012. 
Question : Which medical condition does Robert Ledley suffer from?

SOLUTION: Alzheimer's disease

PROBLEM: Context : Vetle Vislie (21 September 1858 -- 7 February 1933) was a Norwegian educationalist and writer. 
Question : When was Vetle Vislie's death?

SOLUTION:
7 February 1933