Date: 201509
Local time of day: 1801-2400
Location: ZDC.ARTCC, VA
Flight conditions: Mixed
Weather elements / visibility: Icing
Light: Night
Aircraft: Fighter
Operator: Personal
Operating under: Part 91
Flight plan: IFR
Mission: Personal
Flight phase: Cruise
Airspace: Class E ZDC
ATC / advisory: Center ZDC
Second aircraft: Fighter
Reporter organization: Government
Reporter function: Instructor; Enroute
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Situational Awareness; Confusion; Distraction
Second reporter function: Trainee
Anomaly: ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Weather / Turbulence
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Separated Traffic; Air Traffic Control Provided Assistance; Flight Crew Returned To Clearance
Contributing factors: Procedure; Human Factors
Primary problem: Human Factors

Narrative: I was giving training at the sectors this occurred at. Both Aircraft came from sector 22 which is SW of the sector we were working and were going to 2W6. Sector 22 called over and said that Aircraft X was going to cancel IFR and wanted to join up in a formation flight with Aircraft Y. We know that you could not do this with general aviation aircraft. We took radar on both aircraft; Aircraft Y was at 17;000 feet in front of Aircraft X who was assigned 14;000 feet but was climbing through his altitude. Aircraft X went up to 145 and 147 and then finally back down to 14;000 feet. My trainee verified with pilot to make sure he was level at 14;000 feet and Aircraft X finally was level. Then the aircraft wanted higher because he couldn't hold altitude due to the weather and turbulence. So we climbed Aircraft X to 16;000 feet and everything was ok for a couple minutes. Both Aircraft Y and Aircraft X were going to the same airport. Aircraft X was a little faster than Aircraft Y; but Aircraft Y was at 17;000 feet and Aircraft X was at 16;000 feet. Then Aircraft X jumped up a couple hundred feet again which caused us to lose separation with Aircraft Y! Aircraft X came back and said his instruments were giving him conflicted reading and he had vertigo! Once we saw Aircraft X could not hold altitude we turned Aircraft Y 30 degrees to the left to keep the aircraft apart and separated. We did end up declaring an emergency for Aircraft X and tried to ask him to land at nearest airport. The pilot wanted to stay at 16;000 feet because it was clear and he could see. Both aircraft ended up landing at their original airport. We coordinated everything with the proper sectors and approach facilities. The pilot seemed very nervous and somewhat confused but once he got his bearings back he was a lot better. He did not want to change altitude or a land at a closer airport. In the end it all ended up working out; but in my opinion Aircraft X got instrument icing from the pitot tubes in front of the aircraft which gave him all the false readings on his instruments. ELMS or actual class on what pilots experience with instrument icing and vertigo.


Second narrative: While training at R21/R33 I accepted radar on Aircraft Y level at 17;000 ft and Aircraft X level at 14;000 ft who were both flying from INT to 2W6 and knew about each other. Small areas of moderate precipitation were depicted on the radar scope in the vicinity of both aircraft. Prior to the pilot of Aircraft X checking on to my frequency and continuing for approximately the next 15 minutes; I observed the MODE C read out of this aircraft to be +/- 1;000ft from the assigned altitude. At check on his altitude read 14;800 ft and the pilot advised he was descending to 14;000 ft and experiencing turbulence and vertigo. I asked the pilot if he needed assistance or if he was declaring an emergency. The pilot said negative and continued to deviate his altitude up and down. He asked to climb. I climbed the aircraft to 16;000 ft. The pilot advised he was receiving conflicting information from his instruments. I asked if he was qualified and capable of IFR to which he replied affirmative. I was then instructed to declare an emergency for him; which I did. Aircraft X deviated to 16;400 ft while Aircraft Y was at 17;000 ft and 2.72nm to his 12 o'clock. This created a loss of separation of 2.72 nm and 600 ft. I turned Aircraft Y 30 degrees left to get him out of the way. Aircraft X wanted to stay at 16;000 ft because he then found a layer of clear sky where he could see the horizon and maintain his altitude. I then suggested he land if able. He advised he wanted to keep going to 2W6 and later told me he had 1 soul on board and 55 minutes of fuel remaining. The aircraft continued to 2W6 and safely landed without further incident.


Synopsis: ZDC Instructor and Developmental report of a situation where two aircraft wanted to become a flight. The controllers did not allow this and one of the aircraft cannot keep altitude and continually climbs and descends. Controllers find out pilot is having icing and vertigo problems and then separate the aircraft even more. A loss of separation occurs when the pilot initially climbs out of assigned altitude.