Air carrier-large transport close proximity with unk while on climb out from atl.

Attributes
ACN	104068
Time
Date	198902
Day	Tue
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : atl
State Reference	GA
Altitude	msl bound lower : 10000 msl bound upper : 11200
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : atl
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	climbout : intermediate altitude
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : commercial pilot : atp
Experience	flight time last 90 days : 200 flight time total : 15000 flight time type : 12000
ASRS Report	104068
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	altitude deviation : overshoot conflict : airborne less severe non adherence : required legal separation non adherence : clearance
Independent Detector	other controllera other flight crewa
Resolutory Action	flight crew : took evasive action other
Consequence	Other
Miss Distance	horizontal : 1000 vertical : 500
Supplementary
Primary Problem	Ambiguous
Air Traffic Incident	Pilot Deviation other

Narrative:

After departure from atl we were cleared to turn left heading 190 degrees, climb to 10000'. During climb departure control cleared us to '200.' later in climb departure called with traffic advisory (1 O'clock, (?) mi, level 11000'). We responded that traffic 'in sight.' climbing through +/-10300 the traffic appeared very close to meeting us and we passed 11000'. I started an aggressive level off at the same time departure control told us to level off at 10000'. The 11000' traffic passed above and slightly behind us. After discussion with atl departure control he meant, 'heading 200, not FL200.' we read back, 'FL200,' set our altitude alerter to 20000'. There was no question in the copilot's, F/east's or my mind that we were cleared to do anything else but climb to 20000.' I feel that our 'understanding of the clearance to climb,' and our readback and departure's possible saturation that led to their misunderstanding of our readback led to a potentially disastrous situation. I feel that that particular ATC controller learned as much as I did as a result of this incident.

Original NASA ASRS Text

Title: ACR-LGT CLOSE PROX WITH UNK WHILE ON CLIMB OUT FROM ATL.

Narrative: AFTER DEP FROM ATL WE WERE CLRED TO TURN LEFT HDG 190 DEGS, CLB TO 10000'. DURING CLB DEP CTL CLRED US TO '200.' LATER IN CLB DEP CALLED WITH TFC ADVISORY (1 O'CLOCK, (?) MI, LEVEL 11000'). WE RESPONDED THAT TFC 'IN SIGHT.' CLBING THROUGH +/-10300 THE TFC APPEARED VERY CLOSE TO MEETING US AND WE PASSED 11000'. I STARTED AN AGGRESSIVE LEVEL OFF AT THE SAME TIME DEP CTL TOLD US TO LEVEL OFF AT 10000'. THE 11000' TFC PASSED ABOVE AND SLIGHTLY BEHIND US. AFTER DISCUSSION WITH ATL DEP CTL HE MEANT, 'HDG 200, NOT FL200.' WE READ BACK, 'FL200,' SET OUR ALT ALERTER TO 20000'. THERE WAS NO QUESTION IN THE COPLT'S, F/E'S OR MY MIND THAT WE WERE CLRED TO DO ANYTHING ELSE BUT CLB TO 20000.' I FEEL THAT OUR 'UNDERSTANDING OF THE CLRNC TO CLB,' AND OUR READBACK AND DEP'S POSSIBLE SATURATION THAT LED TO THEIR MISUNDERSTANDING OF OUR READBACK LED TO A POTENTIALLY DISASTROUS SITUATION. I FEEL THAT THAT PARTICULAR ATC CTLR LEARNED AS MUCH AS I DID AS A RESULT OF THIS INCIDENT.

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.