Air carrier Y had less than standard separation from bmb X flight. System error.

Attributes
ACN	151233
Time
Date	199007
Day	Tue
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : ene
State Reference	ME
Altitude	msl bound lower : 28500 msl bound upper : 29000
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zbw
Operator	other
Make Model Name	Military Transport
Flight Phase	cruise other descent other
Route In Use	enroute : direct
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	cruise other descent other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 6
ASRS Report	151233
Person 2
Affiliation	government : military
Function	flight crew : captain oversight : pic
Qualification	pilot : military
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	other other : unspecified atc
Resolutory Action	none taken : detected after the fact
Consequence	faa : investigated
Miss Distance	horizontal : 6000 vertical : 500
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Flight of 2 bmb's X assigned fl280b290. Issued discretionary descent to fl240b250. Sector extremely busy. Air carrier Y issued descent to FL290 (traffic was bmb flight). Data block of bmb X indicated FL280 descending to FL240 so controller used FL290 for descending air carrier. Second bmb was at FL285. It is possible that there was a loss of sep. Present ATC rules do not require additional vertical sep for a formation flight. By using 'minimum' vertical sep it is possible to loose 'minimum' sep with wingmen.

Original NASA ASRS Text

Title: ACR Y HAD LESS THAN STANDARD SEPARATION FROM BMB X FLT. SYSTEM ERROR.

Narrative: FLT OF 2 BMB'S X ASSIGNED FL280B290. ISSUED DISCRETIONARY DSNT TO FL240B250. SECTOR EXTREMELY BUSY. ACR Y ISSUED DSNT TO FL290 (TFC WAS BMB FLT). DATA BLOCK OF BMB X INDICATED FL280 DSNDING TO FL240 SO CTLR USED FL290 FOR DSNDING ACR. SECOND BMB WAS AT FL285. IT IS POSSIBLE THAT THERE WAS A LOSS OF SEP. PRESENT ATC RULES DO NOT REQUIRE ADDITIONAL VERT SEP FOR A FORMATION FLT. BY USING 'MINIMUM' VERT SEP IT IS POSSIBLE TO LOOSE 'MINIMUM' SEP WITH WINGMEN.

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.