Air carrier X had less than standard separation from aircraft Y on approach. System error.

Attributes
ACN	270503
Time
Date	199405
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : iad
State Reference	VA
Altitude	msl bound lower : 2000 msl bound upper : 2000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : iad
Operator	common carrier : air carrier
Make Model Name	B727 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	other : unknown
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 120 flight time total : 12500 flight time type : 7100
ASRS Report	270503
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation non adherence : published procedure
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	Other
Miss Distance	horizontal : 9000 vertical : 0
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

On approach to iad ILS 19L, controller stated that air carrier X was 1.5 mi from preceding aircraft Y, advised to 'slow down,' then amended to climb to 4000 and maintain localizer track. WX was IMC 500 ft overcast. Speed was as assigned by ATC.

Original NASA ASRS Text

Title: ACR X HAD LTSS FROM ACFT Y ON APCH. SYS ERROR.

Narrative: ON APCH TO IAD ILS 19L, CTLR STATED THAT ACR X WAS 1.5 MI FROM PRECEDING ACFT Y, ADVISED TO 'SLOW DOWN,' THEN AMENDED TO CLB TO 4000 AND MAINTAIN LOC TRACK. WX WAS IMC 500 FT OVCST. SPD WAS AS ASSIGNED BY ATC.

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.