<< >> NASA ASRS Report 639725, February 2004

An MD11 did not descend from FL390 to FL350 as instructed, and a B737 at FL410 descended instead, resulting in a conflict with a third aircraft at FL390.

Attributes
ACN	639725
Time
Date	200402
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : bna.airport
State Reference	TN
Altitude	msl bound lower : 39000 msl bound upper : 41000
Environment
Flight Conditions	VMC
Weather Elements	Turbulence
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zme.artcc
Operator	common carrier : air carrier
Make Model Name	MD-11
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zme.artcc
Operator	common carrier : air carrier
Make Model Name	B737-800
Operating Under FAR Part	Part 121
Flight Phase	cruise : enroute altitude change
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 19
ASRS Report	639725
Person 2
Affiliation	government : faa
Function	controller : handoff position
Qualification	controller : developmental
Experience	controller military : 10 controller radar : 17 controller time certified in position1 : 6 controller time certified in position2 : 7
ASRS Report	639278
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne critical non adherence : published procedure non adherence : required legal separation non adherence other
Independent Detector	atc equipment : conflict alert other controllera other controllerb other flight crewa other flight crewb other other : 5
Resolutory Action	none taken : anomaly accepted other
Consequence	faa : investigated
Miss Distance	horizontal : 6600 vertical : 1300
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error Pilot Deviation

Narrative:

Air carrier X was issued clearance to FL350 from FL390, and air carrier Y took his clearance and descended from FL410 and became in conflict with air carrier Z at FL390.

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Original NASA ASRS Text

Title: AN MD11 DID NOT DSND FROM FL390 TO FL350 AS INSTRUCTED, AND A B737 AT FL410 DSNDED INSTEAD, RESULTING IN A CONFLICT WITH A THIRD ACFT AT FL390.

Narrative: ACR X WAS ISSUED CLRNC TO FL350 FROM FL390, AND ACR Y TOOK HIS CLRNC AND DSNDED FROM FL410 AND BECAME IN CONFLICT WITH ACR Z AT FL390.

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.