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D01 controller chronicles possible loss of separation because of an apparent unexpected speed reduction by an air carrier flight crew and suspects operational deviation by ZDV controller regarding airspace LOA.
| Attributes | |
| ACN | 650982 |
| Time | |
| Date | 200503 |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : den.airport |
| State Reference | CO |
| Altitude | msl bound lower : 18000 msl bound upper : 19000 |
| Environment | |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zdv.artcc tracon : d01.tracon tower : jnu.tower |
| Operator | common carrier : air carrier |
| Make Model Name | Commercial Fixed Wing |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent : intermediate altitude |
| Route In Use | arrival star : n/a |
| Flight Plan | IFR |
| Aircraft 2 | |
| Controlling Facilities | artcc : zdv.artcc tracon : d01.tracon |
| Operator | common carrier : air carrier |
| Make Model Name | Commercial Fixed Wing |
| Operating Under FAR Part | Part 121 |
| Route In Use | arrival star : n/a |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : approach |
| Qualification | controller : radar |
| Experience | controller military : 4 controller non radar : 3 controller radar : 23 controller supervisory : 4 |
| ASRS Report | 650982 |
| Person 2 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Events | |
| Anomaly | conflict : airborne less severe non adherence : published procedure non adherence : required legal separation other anomaly |
| Independent Detector | other controllera |
| Resolutory Action | controller : issued new clearance flight crew : took evasive action |
| Supplementary | |
| Problem Areas | ATC Human Performance Flight Crew Human Performance |
| Primary Problem | Ambiguous |
Narrative:
On mar/xa/05 while working the AR1 position; I received 2 aircraft from ZDV. The first aircraft was aircraft X descending to FL180. The second aircraft; call sign unknown; was at FL190. Aircraft X entered den approach airspace at an altitude not in accordance with our LOA and without coordination. They were also at FL180 and the altimeter was 29.91. The second aircraft was overtaking the first and may not have been the required 5 NM in trail. Aircraft X was assigned 280 KTS by ZDV and checked in slowing to 250 KTS. Aircraft X later slowed below 250 KTS without advising; while on downwind. I am unable to find out if they needed to advise that they were slowing again; or if the first transmission when they checked in 'slowing to 250' took away all speed assignments.
Original NASA ASRS Text
Title: D01 CTLR CHRONICLES POSSIBLE LOSS OF SEPARATION BECAUSE OF AN APPARENT UNEXPECTED SPD REDUCTION BY AN ACR FLT CREW AND SUSPECTS OPDEV BY ZDV CTLR REGARDING AIRSPACE LOA.
Narrative: ON MAR/XA/05 WHILE WORKING THE AR1 POS; I RECEIVED 2 ACFT FROM ZDV. THE FIRST ACFT WAS ACFT X DSNDING TO FL180. THE SECOND ACFT; CALL SIGN UNKNOWN; WAS AT FL190. ACFT X ENTERED DEN APCH AIRSPACE AT AN ALT NOT IN ACCORDANCE WITH OUR LOA AND WITHOUT COORD. THEY WERE ALSO AT FL180 AND THE ALTIMETER WAS 29.91. THE SECOND ACFT WAS OVERTAKING THE FIRST AND MAY NOT HAVE BEEN THE REQUIRED 5 NM IN TRAIL. ACFT X WAS ASSIGNED 280 KTS BY ZDV AND CHKED IN SLOWING TO 250 KTS. ACFT X LATER SLOWED BELOW 250 KTS WITHOUT ADVISING; WHILE ON DOWNWIND. I AM UNABLE TO FIND OUT IF THEY NEEDED TO ADVISE THAT THEY WERE SLOWING AGAIN; OR IF THE FIRST XMISSION WHEN THEY CHKED IN 'SLOWING TO 250' TOOK AWAY ALL SPD ASSIGNMENTS.
Data retrieved from NASA's ASRS site as of January 2009 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.