Air carrier Y was given an early descent and conflicted with air carrier X, who was also descending.

Attributes
ACN	108690
Time
Date	198904
Day	Tue
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : shb
State Reference	IN
Altitude	msl bound lower : 23500 msl bound upper : 24100
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zid
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	descent other
Route In Use	enroute : direct
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	descent other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller non radar : 7 controller radar : 4
ASRS Report	108690
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	non adherence : required legal separation non adherence : published procedure
Independent Detector	atc equipment other atc equipment : unspecified other controllera
Resolutory Action	controller : issued new clearance none taken : insufficient time
Consequence	faa : investigated
Miss Distance	horizontal : 24600 vertical : 500
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Air carrier Y was told to start descent 'now' for traffic at XX43Z. Air carrier X checked on frequency out of FL305 for FL240 asking 'how far from rid?' at XX46Z. Unknown to me, air carrier Y had a crossing restriction to cross 50 mi west of rid at FL240. I told air carrier Y he was 56 mi out. 30 seconds later I lost mode C readout on air carrier Y and C/a activated shortly after. At XX47 air carrier Y's mode C returned displaying FL246 descending to FL240. Adep activated at XX47:36Z. We calculated a descent rate of 6200' in 48 seconds. Air carrier Y leveled at FL241 as air carrier X left FL235 descending to FL190. 4.1 mi apart.

Original NASA ASRS Text

Title: ACR Y WAS GIVEN AN EARLY DESCENT AND CONFLICTED WITH ACR X, WHO WAS ALSO DESCENDING.

Narrative: ACR Y WAS TOLD TO START DSCNT 'NOW' FOR TFC AT XX43Z. ACR X CHKED ON FREQ OUT OF FL305 FOR FL240 ASKING 'HOW FAR FROM RID?' AT XX46Z. UNKNOWN TO ME, ACR Y HAD A XING RESTRICTION TO CROSS 50 MI W OF RID AT FL240. I TOLD ACR Y HE WAS 56 MI OUT. 30 SECS LATER I LOST MODE C READOUT ON ACR Y AND C/A ACTIVATED SHORTLY AFTER. AT XX47 ACR Y'S MODE C RETURNED DISPLAYING FL246 DSNDING TO FL240. ADEP ACTIVATED AT XX47:36Z. WE CALCULATED A DSCNT RATE OF 6200' IN 48 SECS. ACR Y LEVELED AT FL241 AS ACR X LEFT FL235 DSNDING TO FL190. 4.1 MI APART.

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.