<< >> NASA ASRS Report 140400, March 1990

Operational error of allowing air carrier flight to almost climb through occupied altitude of another aircraft flight creates loss of separation with the potential of a near midair collision or actual midair collision.

Attributes
ACN	140400
Time
Date	199003
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : aml
State Reference	VA
Altitude	msl bound lower : 35000 msl bound upper : 35200
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	climbout : intermediate altitude
Route In Use	enroute airway : j149
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Widebody, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : flight engineer
Experience	flight time total : 15000
ASRS Report	140400
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 5000 flight time type : 900
ASRS Report	141202
Events
Anomaly	non adherence : required legal separation other anomaly other
Independent Detector	other flight crewa
Resolutory Action	controller : issued new clearance
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 1500 vertical : 1800
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Our large transport was cleared to FL390. We broke out on top at about FL310. At about FL340 we spotted converging traffic at 11 O'clock high. I asked center the altitude of the traffic. The center's reply was, 'level off at 350.' we were already through FL346. A smooth level off took us up to FL352 and then back down to FL350. As we watched another air carrier widebody transport pass directly over us, center confirmed his altitude as FL370. Had we been IMC, I feel a midair was an 80-90% probability.

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Original NASA ASRS Text

Title: OPERATIONAL ERROR OF ALLOWING ACR FLT TO ALMOST CLIMB THROUGH OCCUPIED ALT OF ANOTHER ACFT FLT CREATES LOSS OF SEPARATION WITH THE POTENTIAL OF A NMAC OR ACTUAL MIDAIR COLLISION.

Narrative: OUR LGT WAS CLRED TO FL390. WE BROKE OUT ON TOP AT ABOUT FL310. AT ABOUT FL340 WE SPOTTED CONVERGING TFC AT 11 O'CLOCK HIGH. I ASKED CENTER THE ALT OF THE TFC. THE CENTER'S REPLY WAS, 'LEVEL OFF AT 350.' WE WERE ALREADY THROUGH FL346. A SMOOTH LEVEL OFF TOOK US UP TO FL352 AND THEN BACK DOWN TO FL350. AS WE WATCHED ANOTHER ACR WDB PASS DIRECTLY OVER US, CENTER CONFIRMED HIS ALT AS FL370. HAD WE BEEN IMC, I FEEL A MIDAIR WAS AN 80-90% PROBABILITY.

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.