Less than standard separation when air carrier-large transport is allowed to climb to the altitude of an inbound air carrier-large transport.

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Attributes
ACN	96777
Time
Date	198810
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : dfw
State Reference	TX
Altitude	msl bound lower : 9300 msl bound upper : 10000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : dfw
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	climbout : intermediate altitude descent other
Route In Use	departure other
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	cruise 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 : 210 flight time total : 24000 flight time type : 11000
ASRS Report	96777
Person 2
Affiliation	company : air carrier
Function	flight crew : second officer
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 20 flight time total : 2300 flight time type : 20
ASRS Report	96529
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation
Independent Detector	other controllera other flight crewa
Resolutory Action	controller : issued new clearance flight crew : took evasive action none taken : insufficient time
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 0 vertical : 700
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

On departure dfw we saw large transport Y at 11:30 at about 10 mi. We assumed it was 11000' on arrival to dfw. We were assigned 10000'. As we passed 9200' or so controller called, 'large transport X level off at 9000'. I say again, level off 9000'.' we pushed over hard at about 9300'. Aircraft responded and we descended to 9000'. At top of push over large transport Y passed directly overhead at what I estimated to be 700' above us. I could be wrong, but it appeared to be at 10000'. I questioned the controller and she responded that the tower had miss-set the radar altimeter by 1.00' heading. Therefore, all altitudes were off by 1000'. I later talked by telephone to the supervisor in charge and was given the same explanation. However, even this does not explain closeness of the other aircraft since there would still have been 1700' sep and not the perceived 700' near miss.

Original NASA ASRS Text

Title: LESS THAN STANDARD SEPARATION WHEN ACR-LGT IS ALLOWED TO CLIMB TO THE ALT OF AN INBOUND ACR-LGT.

Narrative: ON DEP DFW WE SAW LGT Y AT 11:30 AT ABOUT 10 MI. WE ASSUMED IT WAS 11000' ON ARR TO DFW. WE WERE ASSIGNED 10000'. AS WE PASSED 9200' OR SO CTLR CALLED, 'LGT X LEVEL OFF AT 9000'. I SAY AGAIN, LEVEL OFF 9000'.' WE PUSHED OVER HARD AT ABOUT 9300'. ACFT RESPONDED AND WE DSNDED TO 9000'. AT TOP OF PUSH OVER LGT Y PASSED DIRECTLY OVERHEAD AT WHAT I ESTIMATED TO BE 700' ABOVE US. I COULD BE WRONG, BUT IT APPEARED TO BE AT 10000'. I QUESTIONED THE CTLR AND SHE RESPONDED THAT THE TWR HAD MISS-SET THE RADAR ALTIMETER BY 1.00' HDG. THEREFORE, ALL ALTS WERE OFF BY 1000'. I LATER TALKED BY TELEPHONE TO THE SUPVR IN CHARGE AND WAS GIVEN THE SAME EXPLANATION. HOWEVER, EVEN THIS DOES NOT EXPLAIN CLOSENESS OF THE OTHER ACFT SINCE THERE WOULD STILL HAVE BEEN 1700' SEP AND NOT THE PERCEIVED 700' NEAR MISS.

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.