ZTL controller reported of holding aircraft for clt due to thunderstorms. One aircraft was assigned ...

Narrative:

Thunderstorms in the clt area. Clt approach shut us off with about 5 aircraft inbound; the closest about 15 miles away from airspace boundary. I cleared aircraft X to hold at btsey with detailed holding down to 130; with aircraft Y established in holding at 120. I noticed that aircraft X was below the assigned altitude; and questioned the pilot. Aircraft X acknowledged and climbed back up to 130. Approximately 30 seconds later aircraft X descended back down below 130. I don't believe separation was ever lost with aircraft X and aircraft Y. At this point the frequency was very congested (another clt holding aircraft low on fuel); so I vectored aircraft X out to the east just to get the aircraft into an area that had no other aircraft. The pilot of aircraft X did not demonstrate to me that he could keep the aircraft level in a holding pattern. About 5 minutes later; I turned the aircraft left to a 280 heading to reestablish holding; and then went on to other things. When I looked back; aircraft X had turned due south; directly into clt approach. I attempted to correct the pilot and turned to a 010 heading (I believe). After 20-30 seconds; I didn't see any start of a turn; so I continued the turn to a 340 heading with emphasis. I was very busy on the frequency and do not know if my D side coordinated with clt approach before the aircraft entered their airspace; but don't believe it happened in a timely manner.

Original NASA ASRS Text

Title: ZTL Controller reported of holding aircraft for CLT due to thunderstorms. One aircraft was assigned holding instructions but kept on busting altitude. Controller moved aircraft away from other traffic and then the aircraft did not fly as instructed.

Narrative: Thunderstorms in the CLT area. CLT approach shut us off with about 5 aircraft inbound; the closest about 15 miles away from airspace boundary. I cleared Aircraft X to hold at BTSEY with detailed holding down to 130; with Aircraft Y established in holding at 120. I noticed that Aircraft X was below the assigned altitude; and questioned the pilot. Aircraft X acknowledged and climbed back up to 130. Approximately 30 seconds later Aircraft X descended back down below 130. I don't believe separation was ever lost with Aircraft X and Aircraft Y. At this point the frequency was very congested (another CLT holding aircraft low on fuel); so I vectored Aircraft X out to the east just to get the aircraft into an area that had no other aircraft. The pilot of Aircraft X did not demonstrate to me that he could keep the aircraft level in a holding pattern. About 5 minutes later; I turned the aircraft left to a 280 heading to reestablish holding; and then went on to other things. When I looked back; Aircraft X had turned due south; directly into CLT approach. I attempted to correct the pilot and turned to a 010 heading (I believe). After 20-30 seconds; I didn't see any start of a turn; so I continued the turn to a 340 heading with emphasis. I was very busy on the frequency and do not know if my D side coordinated with CLT approach before the aircraft entered their airspace; but don't believe it happened in a timely manner.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	1352235
Time
Date	201605
Local Time Of Day	1801-2400
Place
Locale Reference	ZTL.ARTCC
State Reference	GA
Environment
Light	Night
Aircraft 1
Make Model Name	Light Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Flight Plan	IFR
Aircraft 2
Make Model Name	Medium Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Person 1
Function	Enroute
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 22.6
Events
Anomaly	ATC Issue All Types Airspace Violation All Types Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance Deviation - Track / Heading All Types Inflight Event / Encounter Weather / Turbulence

ZTL controller reported of holding aircraft for clt due to thunderstorms. One aircraft was assigned holding instructions but kept on busting altitude. Controller moved aircraft away from other traffic and then the aircraft did not fly as instructed.