ATC controller overload. Traffic separation.

Attributes
ACN	300093
Time
Date	199503
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : atl
State Reference	GA
Altitude	msl bound lower : 21000 msl bound upper : 23000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : ztl
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent other
Route In Use	arrival other arrival star : star
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : instrument pilot : commercial
Experience	flight time last 90 days : 150 flight time total : 8800 flight time type : 1000
ASRS Report	300093
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	other anomaly other
Independent Detector	other flight crewa
Resolutory Action	controller : issued new clearance
Consequence	Other
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Deviation

Narrative:

Flight X from orl to atl approximately 20 DME south of husky intersection on sierra arrival proceeding direct to husky at 310 KTS controller cleared us to cross husky at 14000 ft. We started down but realized that we could not make crossing restr. The frequency was very congested, and by the time we were able to tell the controller that we couldn't make the restr we were at 21500 ft. Controller then instructed us to turn to a 90 degree heading with no further instruction on altitude. When we asked what altitude he wanted, he said FL230. Since we were already at FL215 we told him we would level off at FL210. The frequency at the time was very congested, and it sounded as though the controller was reaching the point of overload. A previous aircraft (possibly Y) had a miscom with the controller which resulted in a similar altitude confusion. After our turn to 90 degrees, and level at FL210, the controller started to clear an aircraft overhead us at FL220 down to FL210, but corrected his mistake immediately. WX in the area was a contributing factor. Due to the large number of arrs, and deteriorating WX conditions, the controller appeared to be reaching the point of overload.

Original NASA ASRS Text

Title: ATC CTLR OVERLOAD. TFC SEPARATION.

Narrative: FLT X FROM ORL TO ATL APPROX 20 DME S OF HUSKY INTXN ON SIERRA ARR PROCEEDING DIRECT TO HUSKY AT 310 KTS CTLR CLRED US TO CROSS HUSKY AT 14000 FT. WE STARTED DOWN BUT REALIZED THAT WE COULD NOT MAKE XING RESTR. THE FREQ WAS VERY CONGESTED, AND BY THE TIME WE WERE ABLE TO TELL THE CTLR THAT WE COULDN'T MAKE THE RESTR WE WERE AT 21500 FT. CTLR THEN INSTRUCTED US TO TURN TO A 90 DEG HDG WITH NO FURTHER INSTRUCTION ON ALT. WHEN WE ASKED WHAT ALT HE WANTED, HE SAID FL230. SINCE WE WERE ALREADY AT FL215 WE TOLD HIM WE WOULD LEVEL OFF AT FL210. THE FREQ AT THE TIME WAS VERY CONGESTED, AND IT SOUNDED AS THOUGH THE CTLR WAS REACHING THE POINT OF OVERLOAD. A PREVIOUS ACFT (POSSIBLY Y) HAD A MISCOM WITH THE CTLR WHICH RESULTED IN A SIMILAR ALT CONFUSION. AFTER OUR TURN TO 90 DEGS, AND LEVEL AT FL210, THE CTLR STARTED TO CLR AN ACFT OVERHEAD US AT FL220 DOWN TO FL210, BUT CORRECTED HIS MISTAKE IMMEDIATELY. WX IN THE AREA WAS A CONTRIBUTING FACTOR. DUE TO THE LARGE NUMBER OF ARRS, AND DETERIORATING WX CONDITIONS, THE CTLR APPEARED TO BE REACHING THE POINT OF OVERLOAD.

Data retrieved from NASA's ASRS site as of July 2007 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.