Narrative:

This was a training flight. I was the instructor with a student on a dual cross country flight. My student was behind the aircraft, late descending and behind with checklists. He called tower 7 mi out and reported 7 mi northwest of the airport. We were more west than north, but I did not correct my position with tower because I felt the situation did not require more accurate reporting. Tower told us to enter right base for runway 16 and report 3 mi northwest. My student read this back correctly. My student was late to descend, so we started a rapid descent from 7500 ft MSL. We reported 3 mi out and around the same time, I heard there was a twin cessna on right downwind for runway 16. Tower told us to look for the traffic and follow. We reported we were looking for the traffic and entering right base. Next the twin cessna pilot called that he was directly below me and recommended I turn north. He said he was diving to avoid. I took control from my student, turned north, stopped our descent and started a full power climb. I did not see the twin-cessna until it had passed below me. I never received a traffic avoidance call from tower. Tower said later that he did not see me until the near miss. We did have all our aircraft lights on. When I finally saw the twin cessna, he was 2 O'clock low flying away from me about 1500 ft from me. I have no way of knowing for sure how close we came because I never saw the other aircraft, but I estimate 500 ft vertically. I believe my student's high workload, my high workload managing him, dusk lighting conditions, our range position report and rapid descent contributed to the near miss. Because of my student's rapid descent, I believe we closed to our 3 mi reporting point faster than tower anticipated, which, along with tower's inability to locate my aircraft visually, placed us in a position close to the twin cessna. Better visual scanning, more accurate position reporting, and better workload management as an instructor could have helped prevent the situation.

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Original NASA ASRS Text

Title: INSTRUCTOR PLT AND STUDENT HAVE CLOSE ENCOUNTER WITH TWIN CESSNA IN THE TFC PATTERN TURNING BASE LEG AT GCC.

Narrative: THIS WAS A TRAINING FLT. I WAS THE INSTRUCTOR WITH A STUDENT ON A DUAL XCOUNTRY FLT. MY STUDENT WAS BEHIND THE ACFT, LATE DSNDING AND BEHIND WITH CHKLISTS. HE CALLED TWR 7 MI OUT AND RPTED 7 MI NW OF THE ARPT. WE WERE MORE W THAN N, BUT I DID NOT CORRECT MY POS WITH TWR BECAUSE I FELT THE SIT DID NOT REQUIRE MORE ACCURATE RPTING. TWR TOLD US TO ENTER R BASE FOR RWY 16 AND RPT 3 MI NW. MY STUDENT READ THIS BACK CORRECTLY. MY STUDENT WAS LATE TO DSND, SO WE STARTED A RAPID DSCNT FROM 7500 FT MSL. WE RPTED 3 MI OUT AND AROUND THE SAME TIME, I HEARD THERE WAS A TWIN CESSNA ON R DOWNWIND FOR RWY 16. TWR TOLD US TO LOOK FOR THE TFC AND FOLLOW. WE RPTED WE WERE LOOKING FOR THE TFC AND ENTERING R BASE. NEXT THE TWIN CESSNA PLT CALLED THAT HE WAS DIRECTLY BELOW ME AND RECOMMENDED I TURN N. HE SAID HE WAS DIVING TO AVOID. I TOOK CTL FROM MY STUDENT, TURNED N, STOPPED OUR DSCNT AND STARTED A FULL PWR CLB. I DID NOT SEE THE TWIN-CESSNA UNTIL IT HAD PASSED BELOW ME. I NEVER RECEIVED A TFC AVOIDANCE CALL FROM TWR. TWR SAID LATER THAT HE DID NOT SEE ME UNTIL THE NEAR MISS. WE DID HAVE ALL OUR ACFT LIGHTS ON. WHEN I FINALLY SAW THE TWIN CESSNA, HE WAS 2 O'CLOCK LOW FLYING AWAY FROM ME ABOUT 1500 FT FROM ME. I HAVE NO WAY OF KNOWING FOR SURE HOW CLOSE WE CAME BECAUSE I NEVER SAW THE OTHER ACFT, BUT I ESTIMATE 500 FT VERTLY. I BELIEVE MY STUDENT'S HIGH WORKLOAD, MY HIGH WORKLOAD MANAGING HIM, DUSK LIGHTING CONDITIONS, OUR RANGE POS RPT AND RAPID DSCNT CONTRIBUTED TO THE NEAR MISS. BECAUSE OF MY STUDENT'S RAPID DSCNT, I BELIEVE WE CLOSED TO OUR 3 MI RPTING POINT FASTER THAN TWR ANTICIPATED, WHICH, ALONG WITH TWR'S INABILITY TO LOCATE MY ACFT VISUALLY, PLACED US IN A POS CLOSE TO THE TWIN CESSNA. BETTER VISUAL SCANNING, MORE ACCURATE POS RPTING, AND BETTER WORKLOAD MGMNT AS AN INSTRUCTOR COULD HAVE HELPED PREVENT THE SIT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.