An air carrier Captain responsed to a TCAS RA after Cape Approach vectored his aircraft toward another air carrier aircraft on a visual approach to MVY.

Narrative

While on a visual approach to Runway 24 at MVY; ATC had made several 'traffic calls' to us. We were paralleling course toward MVY from the southwest with another air carrier. We had been assigned 1;600 FT; which we were at. We didn't have the other aircraft insight yet; but ATC notified the other aircraft of our position. He replied that he had us insight; so they cleared him for the visual approach and told him to head 'right for the numbers.' This meant he was now turning toward us. Approach then told us to widen out and turn more northbound. Our TCAS showed his altitude as +00 from ours. I made visual contact with the air carrier aircraft at this point as he turned toward us and ATC wanted us to then turn toward him. I told the First Officer to not turn; but head toward the airport so that we don't hit the aircraft. The First Officer then got sight of the aircraft and was shocked at how close we were. Our TCAS was calling 'Traffic; traffic' more than a few times during this whole thing. The RA was received when the other aircraft turned toward us. We complied with the RA. Once the other aircraft had begun to descend we were clear of conflict and then turned northbound to enter right traffic for Runway 24. No further incidents were noted. The event occurred when Cape Approach cleared the other air carrier for a visual approach and instructed him to head for the numbers; as well as telling us to turn north. This put both aircraft on a collision course; as we were at the same altitude. The other aircraft pilot did call us insight; however; if we did not have him in sight and complied with ATC's instruction of turning northbound; we may have very well experienced a midair collision. The simple fact is ATC assigned both our aircraft and the other aircraft instructions that put us on a collision course while we were both assigned the same altitude. I would like to see a little less of a 'care free' attitude from Cape Approach with such congested airspace.