Cle coordinator witness a loss of separation event when the final controller tried to fill a 7 1/2 m...

Narrative:

I was observing the arrival radar controller; I was the coordinator. Air carrier Y was on localizer runway 24R cle airport; about 18 miles from runway; at 5000 MSL. Air carrier X was on vector from the south; 20-40knot tailwind; ground speed approx 250kt. Air carrier X was descending from 5000 and vectored in front of air carrier Y. When air carrier X was leaving 5000 controller descended air carrier Y to 4000. Gap was minimal in front of air carrier Y for this sequence. Air carrier X was turned to intercept localizer and crossed slightly; allowing air carrier Y to get less than 3 miles behind at same altitude. Controller expected air carrier Y to get air carrier X so that visual separation could be used but he never got air carrier X in sight. Air carrier Y was vectored off localizer to open up the spacing. One or both aircraft was 10+ miles from airport so that our 2 1/2 mile waiver conditions weren't met. Recommendation; arrival controller is still fairly new and hopefully learned from this event. If controller is going to vector an arrival into a 7 1/2 mile gap between 2 other aircraft; he should ensure that altitude separation is maintained since lateral and visual separation are not assured; especially in a strong quartering crosswind. Relying on visual separation to save the day is not good planning.

Original NASA ASRS Text

Title: CLE coordinator witness a loss of separation event when the final controller tried to fill a 7 1/2 mile hole on final and lost separation; wind factors listed as a contributing factor.

Narrative: I was observing the arrival RADAR controller; I was the coordinator. Air Carrier Y was on localizer Runway 24R CLE airport; about 18 miles from runway; at 5000 MSL. Air Carrier X was on vector from the South; 20-40knot tailwind; ground speed approx 250kt. Air Carrier X was descending from 5000 and vectored in front of Air Carrier Y. When Air Carrier X was leaving 5000 controller descended Air Carrier Y to 4000. Gap was minimal in front of Air Carrier Y for this sequence. Air Carrier X was turned to intercept localizer and crossed slightly; allowing Air Carrier Y to get less than 3 miles behind at same altitude. Controller expected Air Carrier Y to get Air Carrier X so that visual separation could be used but he never got Air Carrier X in sight. Air Carrier Y was vectored off localizer to open up the spacing. One or both aircraft was 10+ miles from airport so that our 2 1/2 mile waiver conditions weren't met. Recommendation; arrival controller is still fairly new and hopefully learned from this event. If controller is going to vector an arrival into a 7 1/2 mile gap between 2 other aircraft; he should ensure that altitude separation is maintained since lateral and visual separation are not assured; especially in a strong quartering crosswind. Relying on visual separation to save the day is not good planning.

Data retrieved from NASA's ASRS site as of April 2012 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.

Attributes
ACN	881498
Time
Date	201004
Local Time Of Day	1801-2400
Place
Locale Reference	CLE.Tower
State Reference	OH
Aircraft 1
Make Model Name	Dash 8 Series Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Initial Approach
Route In Use	Vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	EMB ERJ 145 ER&LR
Operating Under FAR Part	Part 121
Flight Phase	Initial Approach
Route In Use	Vectors
Flight Plan	IFR
Person 1
Function	Coordinator
Qualification	Air Traffic Control Fully Certified
Events
Anomaly	ATC Issue All Types Conflict Airborne Conflict Deviation - Procedural Published Material / Policy

Cle coordinator witness a loss of separation event when the final controller tried to fill a 7 1/2 mile hole on final and lost separation; wind factors listed as a contributing factor.