Less than standard separation between large transport and small transport at same altitude in an ove...

Attributes
ACN	87130
Time
Date	198805
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : ldn
State Reference	VA
Altitude	msl bound lower : 28200 msl bound upper : 27500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	climbout : intermediate altitude cruise other
Route In Use	enroute airway : zdc
Flight Plan	IFR
Aircraft 2
Operator	general aviation : corporate
Make Model Name	Small Transport, Low Wing, 2 Turbojet Eng
Flight Phase	climbout : intermediate altitude cruise other other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 28
ASRS Report	87130
Person 2
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation
Independent Detector	atc equipment other atc equipment : unspecified other controllera
Resolutory Action	controller : issued new clearance none taken : insufficient time other
Consequence	faa : investigated
Miss Distance	horizontal : 21600 vertical : 700
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Large transport at FL280 and small transport Y were approximately 12 mi apart (large transport X trailing small transport Y and overtaking). I climbed small transport Y to FL290 from FL270. Two stet later conflict alert triggered, small transport Y and large transport X were 8 mile 8 min apart and small transport Y leaving FL280. In looking at the ca I confused large transport X altitude and descended small transport Y back to FL280. Upon realizing both aircraft would be at FL280 about 30 second later, I descended small transport Y to FL270 and climbed large transport X to FL290. When the aircraft were 700' apart their proximity was 3.6 mi.

Original NASA ASRS Text

Title: LESS THAN STANDARD SEPARATION BETWEEN LGT AND SMT AT SAME ALT IN AN OVERTAKE SITUATION.

Narrative: LGT AT FL280 AND SMT Y WERE APPROX 12 MI APART (LGT X TRAILING SMT Y AND OVERTAKING). I CLIMBED SMT Y TO FL290 FROM FL270. TWO STET LATER CONFLICT ALERT TRIGGERED, SMT Y AND LGT X WERE 8 MILE 8 MIN APART AND SMT Y LEAVING FL280. IN LOOKING AT THE CA I CONFUSED LGT X ALT AND DESCENDED SMT Y BACK TO FL280. UPON REALIZING BOTH ACFT WOULD BE AT FL280 ABOUT 30 SEC LATER, I DESCENDED SMT Y TO FL270 AND CLIMBED LGT X TO FL290. WHEN THE ACFT WERE 700' APART THEIR PROX WAS 3.6 MI.

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.

Less than standard separation between large transport and small transport at same altitude in an overtake situation.