Air carrier was issued a descent clearance through an occupied altitude, resulting in less than stan...

Attributes
ACN	139956
Time
Date	199003
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : fmy
State Reference	FL
Altitude	msl bound lower : 28000 msl bound upper : 33000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zma
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	descent other
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	cruise other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
ASRS Report	139956
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	non adherence : published procedure non adherence : required legal separation
Independent Detector	atc equipment other atc equipment : unspecified other controllera
Resolutory Action	controller : issued new clearance
Consequence	Other
Miss Distance	horizontal : 24000 vertical : 1200
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Air carrier X at FL330 cleared to FL280. Air carrier Y at FL310. Aircraft passed within 5 mi lateral with less than 2000' sep vertically. Air carrier X began descent (clearance was pilot discretion) within close proximity to air carrier Y. Controller distraction by complex sep situation at another part of the sector. Controller's attention redirected when pilot of air carrier X reported leaving FL330. Immediate action taken to prevent loss of sep, however aircraft were at speeds and on courses that prevented the controller from preserving 5 mi and/or 2000'. Resulting sep: 4 mi/1200'.

Original NASA ASRS Text

Title: ACR WAS ISSUED A DESCENT CLRNC THROUGH AN OCCUPIED ALT, RESULTING IN LESS THAN STANDARD SEPARATION.

Narrative: ACR X AT FL330 CLRED TO FL280. ACR Y AT FL310. ACFT PASSED WITHIN 5 MI LATERAL WITH LESS THAN 2000' SEP VERTICALLY. ACR X BEGAN DSCNT (CLRNC WAS PLT DISCRETION) WITHIN CLOSE PROX TO ACR Y. CTLR DISTR BY COMPLEX SEP SITUATION AT ANOTHER PART OF THE SECTOR. CTLR'S ATTN REDIRECTED WHEN PLT OF ACR X RPTED LEAVING FL330. IMMEDIATE ACTION TAKEN TO PREVENT LOSS OF SEP, HOWEVER ACFT WERE AT SPDS AND ON COURSES THAT PREVENTED THE CTLR FROM PRESERVING 5 MI AND/OR 2000'. RESULTING SEP: 4 MI/1200'.

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.

Air carrier was issued a descent clearance through an occupied altitude, resulting in less than standard separation.