On July 30, 2009, about 2102 eastern daylight time, a Saab 340B, N452XJ, operated by Mesaba Airlines as Flight 3194, diverted to Cherry Capital Airport (KTVC), Traverse City, Michigan, because of a medical emergency involving the sole flight attendant aboard the flight. The 2 pilots, 1 cabin flight attendant, and 30 passengers were uninjured. The scheduled domestic passenger flight was operating under the provisions of 14 Code of Federal Regulations Part 121 while on an instrument flight plan. Dark night visual meteorological conditions prevailed at the time of the incident. The flight departed Detroit Metropolitan Wayne County Airport (KDTW), near Detroit, Michigan, at 2018 and had the intended destination of Sawyer International Airport (KSAW), near Marquette, Michigan. According to the captain, while enroute at 20,000 feet mean sea level there were several knocks on the flight-deck door. As a security precaution, he used the public-address (PA) phone to establish contact with the cabin flight attendant. One of the passengers answered the cabin PA phone and reported that the flight attendant was "no longer coherent" and was performing "numerous unusual activities." The captain advised the passenger to assist the flight attendant to a seat and to stow the service-cart that was blocking the aisle. He then alerted air traffic control that they were diverting to KTVC due to a medical emergency. Prior to landing, the captain coordinated with a passenger to ensure that all passengers were seated and using their seatbelts. The flight made an uneventful landing and was met by paramedics and local law enforcement. The flight attendant was evaluated at a local emergency room (ER). Records from that treatment noted a diagnosis of "Acute anxiety/delirium of uncertain etiology, resolved while in ER." There was no indication in those records of any pre-existing medical or psychiatric conditions. In addition, no pre-existing medical or psychiatric conditions were noted on a September 10, 2008, "Post-job offer medical history questionnaire," required by the airline to be completed by the flight attendant prior to beginning duties. According to federal regulations, a single flight attendant was required for the incident flight. In addition, there are no medical standards for flight attendants currently stipulated by federal regulations.