The purpose of terrorism, wherever it occurs, is to create fear that is disproportionate to the size of any terrorist risk. As Posner indicates, many people have considerable fear of flying even under the best of circumstances. This fear is increased when there is an attempt by a suicide bomber to blow up a plane, as happened in December on a Northwest flight going from Amsterdam to Detroit. The fear is multiplied several fold when attacks are successful. Air travel within the US, and between other countries and the US, took a nosedive after the 9/11, 2001 successful multiple attacks on planes going to New York and Washington.
Yona Rubenstein of Brown University and I have studied in detail reactions to the terrorist attacks on Israeli buses and restaurants during the Intifada period. We show that bus travel in Israel fell significantly after every suicide attack on a bus, while the use of taxes and private cars increased. Similarly, eating in restaurants fell rather sharply after a suicide attack at a restaurant, and this was partially replaced by take out orders. To attract business, restaurants began hiring private guards stationed in front of restaurants, and these guards thwarted several attempted suicide bombings.