An MD80 flight crew took evasive action to avoid a propeller twin that had gone undetected by TCAS.
Synopsis
An MD80 flight crew took evasive action to avoid a propeller twin that had gone undetected by TCAS.
Narrative
We were on the MASTY arrival approximately 5 NM north of GREGG at 9;000 MSL. The First Officer was the pilot flying and I was the pilot not flying. Center called traffic at 12 O'clock 8;600 FT climbing. I don't recall there being any range; just 12 O'clock. The First Officer and I began searching. I was looking at 10 miles and more since there was no urgency in the traffic call. Having not found the traffic I checked TCAS and it showed only one target at 2 O'clock several miles out and climbing. I found that traffic and it appeared that it would pass behind us. The First Officer also spotted the 2 O'clock traffic. While the First Officer and I were looking out the right side of the aircraft the cockpit jumpseat rider said 'there he is straight ahead.' As I turned to look out the front window the jumpseat rider started saying climb! climb! climb! The First Officer immediately started a climb. At 9;300 FT another aircraft not shown by TCAS flew under the right wing at approximately 100 FT-200 FT. As the other aircraft passed the TCAS announced clear of conflict and showed a yellow diamond at our position and -4 altitude; even though it never issued an RA or a TA. At that point a new voice came on the radio. It was Regional Approach on Center frequency. They were watching the situation develop and were waiting for the hand off then cut in on Center's frequency. By then we were clear and began a descent back to 9;000 FT. One Flight Attendant fell and another struggled to keep control of a food service cart that was being pushed back to the galley; eventually getting help from a passenger to control the cart. No injuries were reported.Neither I nor the First Officer saw the traffic. The observer said it was a red and white twin prop and it was close enough that he could see into the cockpit. I talked to the TRACON supervisor on the phone; he said they showed .1 NM and 100 FT separation just prior to passing the traffic.
Second reporter narrative
There was no RA from the TCAS. The TCAS announced clear of conflict.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.