Air Traffic Control Fully Certified
Communication Breakdown
ATC Issue All Types; Airspace Violation All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance; Air Traffic Control Separated Traffic
Human Factors; Procedure
Leveled a B737 at FL220 and stopped a Citation V at FL230. They were separated. Handed the Citation V off to Sector 60 and they descended the Citation V down to eleven thousand right on top of my B737 without control. In response; I climbed my B737 to FL270 in order to avoid a mid air collision. Possibly evaluate and establish some procedures that may include a 'Look and Go' option that could enhance the current operation with minimum coordination. All too often; Sectors in close proximity rely on verbal confirmation to a request; but do not have anything concrete or an established procedure in an SOP.
ZME Controller described a loss of separation event when an aircraft handed off to an adjacent sector was descended without coordination; the reporter suggesting some type of 'Look and Go' coordination procedure be established.