Citation II S2/Bravo (C550)
Flight Crew Flight Engineer; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Flight Crew Last 90 Days 190; Flight Crew Total 28000; Flight Crew Type 2000
Aircraft Equipment Problem Less Severe
General Maintenance Action
Aircraft
We were level at FL300 ATC mentioned traffic 1 o'clock at FL310 opposite direction. We looked for and spotted the traffic which I thought was closer. About the same time; I heard the other aircraft; say that he had a Resolution Advisory to 'descend.' He said he was committed to follow the Resolution Advisory and descend. My Aircraft is not equipped with TCAS. ATC asked us to recycle our Transponder as they were not receiving our Mode 'C.' ATC also asked if we were level at FL300 as assigned. All 3 Altimeters were indicating 30;000 FT. On descent; we were asked to call out every 1;000 FT. After landing I talked to our Maintenance Supervisor who said that the system was recently checked out; tested and certified for RVSM.
CE550 Captain at FL300 is informed of opposite direction traffic at FL310. At about the same time the other aircraft states that they are descending for a TCAS RA. The CE550 was not TCAS equipped and remained level and is informed by ATC that Mode C has failed.