Yesterday, I read a news article about an airline announcing an expected delay of 8 hours because of a mechanical problem (on an island in the Mediterranean). They needed to fly in a mechanic. Then a passenger stepped forward, identified himself as aircraft mechanic, and later fixed the problem.
There are situations, when all kinds of people/occupations are sought ("We need a medic!"), but when was the last time you heard: "Is someone here a DBA?" When would be such a situation?