1.   Some San Francisco hotels saw unexpected additions to their reservation sheets Tuesday and Wednesday as they accommodated tourists stranded here by airport closures.

2.   The airport closures were felt as far away as San Francisco as planes failed to take off because of fear of flying snow.

3.   But the airport closure prevented that.

4.   The airport closures were the result of the Civil Aviation Authority extending its danger zone, which prohibits flight at night or in cloud.