Date: 201702
Local time of day: 1201-1800
Location: ZTL.ARTCC, GA
Aircraft: Small Aircraft
Operator: Military
Flight plan: IFR
Flight phase: Cruise
Airspace: Class A ZTL
ATC / advisory: Center ZTL
Second aircraft: Commercial Fixed Wing
Aircraft component: Oxygen System/General
Component problem: Failed
Reporter organization: Government
Reporter function: Enroute
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Time Pressure; Troubleshooting; Distraction; Situational Awareness
Anomaly: ATC Issue All Types; Airspace Violation All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance; Flight Deck / Cabin / Aircraft Event Illness / Injury
Detector: Person Air Traffic Control; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Returned To Clearance
Contributing factors: Aircraft; Airspace Structure; Staffing; Procedure; Human Factors
Primary problem: Aircraft

Narrative: I was working South/Macon combined with no D side. It was nearing the end of the triple departure push out of ATL. The sector should've been split but the Controller in Charge (CIC) had no staffing and told me the next person back would either split it or be my D side. I was fine and had the traffic under control until the following. Aircraft X was flying west at FL220; Aircraft Y was climbing off of ATL and was level at FL210 for Aircraft X. There was some frequency congestion with aircraft checking on 2 frequencies. Someone [requested aid] and the call sign was cut off so I asked Aircraft Y I was talking to if it was him. Aircraft X said it was him and that he was hypoxic and needed to get down now. I descended Aircraft X to 10000 and told my CIC I needed a D side now. I then told Aircraft Y to fly heading 270 immediately for emergency traffic. The CIC plugged in immediately and started coordinating lower with Macon A80 sector. The CIC asked me what Aircraft X needed and I tried to ask but Aircraft X asked me to standby. Aircraft Y then came back on and asked to confirm that I gave him a LEFT 270. I said affirmative and wondered why he still hadn't turned when I told him immediately. He then turned left to a 270 heading. I didn't intend to turn him left as he was headed south bound and a left would turn him into the emergency traffic! I didn't catch it even when he asked me to confirm it. Aircraft X asked for further descent and I gave him 4000 while my D side was on the line with Macon Sector A80. I then switched Aircraft X to Macon sector A80 without a handoff because I wasn't sure of what traffic they had. I didn't know what else he needed and what he wanted to do and since he wouldn't answer I thought it best that they be talking to him. I later turned Aircraft Y to a 180 heading and then a 200 heading. He was very patient with getting higher and back on course. There were many aircraft leveled off climbing off ATL and the satellite airports and I then tried to get back to normal ops. Aircraft X landed safely thankfully! Separation was never lost; mostly thanks to Aircraft Y not turning when I told him to and Aircraft X's rapid descent. [Suggest] Call the traffic!! I probably won't give a direction to turn next time; although I didn't even intend to give a direction this time either.




Synopsis: Atlanta Center Controller reported an unsafe situation with an aircraft that had to descend and traffic close by.