Less than standard separation between two air carrier. Operational error.

Attributes
ACN	100519
Time
Date	198812
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : tys
State Reference	TN
Altitude	msl bound lower : 28000 msl bound upper : 28000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : ztl tower : sjc
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	climbout : intermediate altitude cruise other
Route In Use	enroute airway : j43
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	climbout : intermediate altitude cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	100519
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 185 flight time total : 7500 flight time type : 2400
ASRS Report	100708
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne less severe non adherence : required legal separation
Independent Detector	other controllera other flight crewa
Resolutory Action	controller : issued new clearance other
Consequence	Other
Miss Distance	horizontal : 18000 vertical : 0
Supplementary
Primary Problem	Ambiguous
Air Traffic Incident	Pilot Deviation Operational Error

Narrative:

We were at 28000' and air carrier Y called in at 27000'. Air carrier Y thought he was cleared to 28000' and climbed to 28000'. The controller saw this and climbed us to 29000'. We were never closer than 3 miles, and there was really no problems. Callback conversation with reporter revealed following information. Has received no followup information reference incident. From conversation on frequency between ATC and air carrier Y it sounded like air carrier Y had received climb to FL280 or at least had read back FL290 west/O ATC correcting. This information not confirmed. Clarified direction of flight for both aircraft. Air carrier X RNAV wbound. Air carrier Y northbound on J43. Flight crew of X got very distinct impression that controller had made an error. Air carrier X went up to FL290 and Y went back down to FL270.

Original NASA ASRS Text

Title: LESS THAN STANDARD SEPARATION BETWEEN TWO ACR. OPERATIONAL ERROR.

Narrative: WE WERE AT 28000' AND ACR Y CALLED IN AT 27000'. ACR Y THOUGHT HE WAS CLRED TO 28000' AND CLBED TO 28000'. THE CTLR SAW THIS AND CLBED US TO 29000'. WE WERE NEVER CLOSER THAN 3 MILES, AND THERE WAS REALLY NO PROBS. CALLBACK CONVERSATION WITH RPTR REVEALED FOLLOWING INFO. HAS RECEIVED NO FOLLOWUP INFO REF INCIDENT. FROM CONVERSATION ON FREQ BTWN ATC AND ACR Y IT SOUNDED LIKE ACR Y HAD RECEIVED CLB TO FL280 OR AT LEAST HAD READ BACK FL290 W/O ATC CORRECTING. THIS INFO NOT CONFIRMED. CLARIFIED DIRECTION OF FLT FOR BOTH ACFT. ACR X RNAV WBOUND. ACR Y NBOUND ON J43. FLT CREW OF X GOT VERY DISTINCT IMPRESSION THAT CTLR HAD MADE AN ERROR. ACR X WENT UP TO FL290 AND Y WENT BACK DOWN TO FL270.

Data retrieved from NASA's ASRS site as of August 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.