When looking up some information for the recent question Have there been any solo flights on airliners?, I found this article that lists several incidents in which a pilot has become incapacitated in flight. One thing that I found particularly surprising was that, in two of the six specific incidents they mention, the person who helped the remaining pilot for the remainder of the flight was actually a flight attendant who had a pilot certificate. This then made me wonder:
How common is it for an airline flight attendant to also be a certificated pilot?