Air carrier X climbed through the altitude of another aircraft due to a misunderstanding of assigned...

Attributes
ACN	108926
Time
Date	198904
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : dfw
State Reference	TX
Altitude	msl bound lower : 11400 msl bound upper : 11900
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : dfw
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport
Navigation In Use	Other Other
Flight Phase	climbout : intermediate altitude
Route In Use	departure sid : sid enroute airway : dfw
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other
Flight Phase	descent other
Route In Use	arrival other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 180 flight time total : 7000 flight time type : 1900
ASRS Report	108926
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : overshoot conflict : airborne less severe non adherence : required legal separation non adherence : published procedure
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance
Consequence	Other
Miss Distance	horizontal : 6000 vertical : 400
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

This was the clearance given to us coming out of dfw: dallas 6 departure greenwood transition as filed, climb and maintain '1-2-thousand.' clearance was read back as such and clearance delivery acknowledged readback. We both questioned the 12000' because SID calls for 10000'. When we switched over to departure control, we told them we were on our way up to '1-2-thousand.' departure control acknowledged. Going through 11400' departure control came back and said he didn't believe he gave us a high altitude. The obvious reason was air carrier Y, an medium large transport at our 11 O'clock position, descending into dfw. Sep between the both of us was approximately 500'. We told the controller that we read back 12000' to them. There was silence for about 10 seconds. He then came back and gave us a clearance to 17000'.

Original NASA ASRS Text

Title: ACR X CLIMBED THROUGH THE ALT OF ANOTHER ACFT DUE TO A MISUNDERSTANDING OF ASSIGNED ALT.

Narrative: THIS WAS THE CLRNC GIVEN TO US COMING OUT OF DFW: DALLAS 6 DEP GREENWOOD TRANSITION AS FILED, CLB AND MAINTAIN '1-2-THOUSAND.' CLRNC WAS READ BACK AS SUCH AND CLRNC DELIVERY ACKNOWLEDGED READBACK. WE BOTH QUESTIONED THE 12000' BECAUSE SID CALLS FOR 10000'. WHEN WE SWITCHED OVER TO DEP CTL, WE TOLD THEM WE WERE ON OUR WAY UP TO '1-2-THOUSAND.' DEP CTL ACKNOWLEDGED. GOING THROUGH 11400' DEP CTL CAME BACK AND SAID HE DIDN'T BELIEVE HE GAVE US A HIGH ALT. THE OBVIOUS REASON WAS ACR Y, AN MLG AT OUR 11 O'CLOCK POS, DSNDING INTO DFW. SEP BTWN THE BOTH OF US WAS APPROX 500'. WE TOLD THE CTLR THAT WE READ BACK 12000' TO THEM. THERE WAS SILENCE FOR ABOUT 10 SECS. HE THEN CAME BACK AND GAVE US A CLRNC TO 17000'.

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.

Air carrier X climbed through the altitude of another aircraft due to a misunderstanding of assigned altitude.