Aircraft X same altitude had less than standard separation from aircraft Y. System error.

Attributes
ACN	313104
Time
Date	199508
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : iad
State Reference	VA
Altitude	msl bound lower : 4700 msl bound upper : 4700
Environment
Flight Conditions	Marginal
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : iad
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	other : unknown
Flight Phase	cruise other
Route In Use	enroute : on vectors
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	government : faa
Function	controller : approach
Qualification	controller : radar
Experience	controller radar : 18
ASRS Report	313104
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : developmental
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	faa : investigated
Miss Distance	horizontal : 9000 vertical : 0
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

I was training a developmental on iad final position. The trainee turned an aircraft X from the downwind towards the final in front of aircraft Y already established straight in. The aircraft were converging when I transmitted to the downwind X to turn to 040 degrees then immediately to 010 degrees and descend to 3000 ft. No reply. I then turned the straight in Y to 060 degrees off the localizer and called traffic 10 O'clock 4 mi. Both aircraft ended up on 060 degrees course 1.5 mi apart at 4700 ft. Aircraft Y, from the downwind turning to 060 degrees, finally replied 'say again.' several contributing factors: trainee had 25 hours on this position but hadn't worked under these conditions, IFR north. Iad doesn't work simultaneous ILS approachs, but staggered approachs (we don't have the proper equipment or staffing). Frequency congestion, blocked xmissions happen frequently because of this. Traffic management coordinator was standing directly behind me talking which was distracting me. I now know why hearback readback is so important.

Original NASA ASRS Text

Title: ACFT X SAME ALT HAD LTSS FROM ACFT Y. SYS ERROR.

Narrative: I WAS TRAINING A DEVELOPMENTAL ON IAD FINAL POS. THE TRAINEE TURNED AN ACFT X FROM THE DOWNWIND TOWARDS THE FINAL IN FRONT OF ACFT Y ALREADY ESTABLISHED STRAIGHT IN. THE ACFT WERE CONVERGING WHEN I XMITTED TO THE DOWNWIND X TO TURN TO 040 DEGS THEN IMMEDIATELY TO 010 DEGS AND DSND TO 3000 FT. NO REPLY. I THEN TURNED THE STRAIGHT IN Y TO 060 DEGS OFF THE LOC AND CALLED TFC 10 O'CLOCK 4 MI. BOTH ACFT ENDED UP ON 060 DEGS COURSE 1.5 MI APART AT 4700 FT. ACFT Y, FROM THE DOWNWIND TURNING TO 060 DEGS, FINALLY REPLIED 'SAY AGAIN.' SEVERAL CONTRIBUTING FACTORS: TRAINEE HAD 25 HRS ON THIS POS BUT HADN'T WORKED UNDER THESE CONDITIONS, IFR N. IAD DOESN'T WORK SIMULTANEOUS ILS APCHS, BUT STAGGERED APCHS (WE DON'T HAVE THE PROPER EQUIP OR STAFFING). FREQ CONGESTION, BLOCKED XMISSIONS HAPPEN FREQUENTLY BECAUSE OF THIS. TFC MGMNT COORDINATOR WAS STANDING DIRECTLY BEHIND ME TALKING WHICH WAS DISTRACTING ME. I NOW KNOW WHY HEARBACK READBACK IS SO IMPORTANT.

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.