Narrative:

While turning a left base leg into mdt runway 31, the tower advised us of traffic at 3100 ft, 5 NM heading west. The first officer was flying, so I asked the tower to keep us advised. The tower then said the traffic was at 2 NM and that we should level off at 3500 ft. The light twin flew almost directly underneath us. The tower also stated that the light twin was not in communication with any facility. Note far 121 supplemental carriers need TCASII! Callback conversation with reporter revealed the following information: an air carrier B727-200 freighter flight crew had a light twin engined aircraft, that the captain thought was possibly a beech baron, fly under them as they were making an approach to mdt. They were thankful, the captain said, that the controller had given them good advisories as they did not see the traffic until it was almost beneath them. He said that this incident points out the need for freight aircraft to be equipped with the TCASII system. The captain has apparently had several nmacs lately and has requested that his company discontinue its practice of removing the TCASII equipment from converted former passenger aircraft. The company is considering his request.

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Original NASA ASRS Text

Title: AN ACR B727 FREIGHTER FLC HAD AN NMAC WITH AN SMT TWIN ENGINED ACFT WHILE TURNING TO ITS BASE LEG ON A VISUAL APCH TO MDT. THE RPTR COMPLAINED THAT THE LACK OF A TCASII MADE THE CONFLICT MORE DANGEROUS THAN IT SHOULD HAVE BEEN.

Narrative: WHILE TURNING A L BASE LEG INTO MDT RWY 31, THE TWR ADVISED US OF TFC AT 3100 FT, 5 NM HDG W. THE FO WAS FLYING, SO I ASKED THE TWR TO KEEP US ADVISED. THE TWR THEN SAID THE TFC WAS AT 2 NM AND THAT WE SHOULD LEVEL OFF AT 3500 FT. THE LIGHT TWIN FLEW ALMOST DIRECTLY UNDERNEATH US. THE TWR ALSO STATED THAT THE LIGHT TWIN WAS NOT IN COMMUNICATION WITH ANY FACILITY. NOTE FAR 121 SUPPLEMENTAL CARRIERS NEED TCASII! CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: AN ACR B727-200 FREIGHTER FLC HAD A LIGHT TWIN ENGINED ACFT, THAT THE CAPT THOUGHT WAS POSSIBLY A BEECH BARON, FLY UNDER THEM AS THEY WERE MAKING AN APCH TO MDT. THEY WERE THANKFUL, THE CAPT SAID, THAT THE CTLR HAD GIVEN THEM GOOD ADVISORIES AS THEY DID NOT SEE THE TFC UNTIL IT WAS ALMOST BENEATH THEM. HE SAID THAT THIS INCIDENT POINTS OUT THE NEED FOR FREIGHT ACFT TO BE EQUIPPED WITH THE TCASII SYSTEM. THE CAPT HAS APPARENTLY HAD SEVERAL NMACS LATELY AND HAS REQUESTED THAT HIS COMPANY DISCONTINUE ITS PRACTICE OF REMOVING THE TCASII EQUIPMENT FROM CONVERTED FORMER PAX ACFT. THE COMPANY IS CONSIDERING HIS REQUEST.

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.