DA40 Instructor pilot with student departing Runway 19 reports a NMAC with a C182 at pattern altitude and opposite direction mid field downwind. Evasive action is taken by the student pilot; narrowly missing the C182 which does not deviate. The C182 pilot had announced overflying the airport with intentions of entering the traffic pattern for Runway 19; but had entered right traffic for Runway 01.

Narrative

I was flight instructor on an aircraft checkout flight with an ATP rated student. We had landed and were about to takeoff from Runway 19 planning to enter the VFR traffic pattern for touch and go landings. Just prior to taking the active runway we heard a transmission from an aircraft identifying itself as [aircraft Y]. [Aircraft Y] announced that they were NW of the airport and were going to overfly the field to the SE at 2;000 FT and then enter the traffic pattern for Runway 19 (the Runway 19 traffic pattern is a left hand pattern and is to the east of the runway). The student made a takeoff from Runway 19 and turned to the downwind leg at the pattern altitude of 1;500 FT. We made the standard radio transmissions turning crosswind and downwind. At about the midfield position the student saw a Cessna 182 on a collision course with us at our altitude and on a reciprocal course. He immediately began a descending left turn to avoid the other aircraft. I spotted the Cessna just as my student was initiating his turn. We passed within 100 to 200 FT both vertically and laterally from the other aircraft. We did not observe any evasive maneuver by the Cessna. The Cessna then left the pattern to the SE and reentered the downwind wind leg of the landing pattern for Runway 19. Both our aircraft landed without further incident. Subsequent radio conversation revealed that the Cessna 182 was in fact [aircraft Y]. They seemed to be unaware of the conflict that had taken place.