The following images prove that it was no missile. The helo cameraman admitted that he filmed the trail for 10 minutes. No ballistic missile would be in view for that length of time. As the airliner approaches the coast the contrail dissapates and it carries on its easterly heading.
Here are some independent images. 
http://abclocal.go.com/kabc/gallery?section=news/local/los_angeles&id=7776159&photo=1
http://abclocal.go.com/kabc/gallery?section=news/local/los_angeles&id=7776159&photo=2
http://abclocal.go.com/kabc/gallery?section=news/local/los_angeles&id=7776159&photo=3
http://abclocal.go.com/kabc/gallery?section=news/local/los_angeles&id=7776159&photo=4
http://abclocal.go.com/kabc/gallery?section=news/local/los_angeles&id=7776159&photo=5
Images from a weather sat. The airliner contrail is shown and is blown south.
