Any Unknown or Unlisted Aircraft Manufacturer
Air Traffic Control Fully Certified
Communication Breakdown; Confusion; Situational Awareness
ATC Issue All Types; Airspace Violation All Types
Air Traffic Control Issued New Clearance; Air Traffic Control Separated Traffic
Airspace Structure; Human Factors; Procedure
I had a trainee on the D-Side. There was an aircraft flashing at us out of about FL200 with FL320 in the Data Block. We looked at the flash. My trainee did a traffic search and determined that the aircraft be stopped at FL300 for traffic. As we were making the call to the high sector; the R-Side took the hand off because the aircraft was already thru FL250 in our shelf and no one was calling us for a hand off or to APPREQ an altitude with us; even though he was in our airspace. We called the high sector to have the aircraft stopped. They said they had taken a point out from another low. So the low side pointed out the aircraft to their high side but did not APPREQ an altitude with us as he busted up through the bottom of our airspace. We told them to stop the aircraft but he said he had already switched the aircraft to us. The aircraft did come over and the R-Side stopped him off and averted an Operational Error. I don't think the low sector even realized that he had busted our airspace because of the shelf out there. He actually called our low side for a point out thru the shelf. That may be why he never called us for the hand off. This is the second time in about a week that an aircraft has come to us from a sector in a stratum below us busting up into our airspace. Both times; the controller thought that putting an altitude in the Data Block was enough and that an APPREQ was not necessary. When an aircraft is that close to the boundary; from the low side it should be verbally coordinated.
ZTL Controller described an unauthorized airspace entry event by a low altitude sector controller who apparently failed to note the airspace shelf structure; the reporter noting verbal coordination was necessary.