You may need more than simply reassurance to prevent panic. Panic often comes out of the blue. It is triggered by processes that work at an unconscious level. To prevent it, changes need to be made at THAT level. We teach this in all the SOAR Courses, such as the ones at http://www.fearofflying.com/relief

As to Southwest, it has the best statistical record of any airline in the world. The age of planes is not an issue as they are re-manufactured every three to four years.