Controller involved in less than standard separation due to arrival rush and poor airline schedule.

Attributes
ACN	201045
Time
Date	199202
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : den
State Reference	CO
Altitude	msl bound lower : 21000 msl bound upper : 21000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdv
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other other
Route In Use	arrival other
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Small Transport, Low Wing, 2 Turboprop Eng
Flight Phase	cruise other other
Route In Use	arrival other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 6
ASRS Report	201045
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	faa : investigated
Miss Distance	horizontal : 24000 vertical : 500
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

At approximately XX30 mdt every day, denver ARTCC traffic management unit (tme) implements a reduced airport acceptance rate of 60-65 aircraft per hour. (Normal acceptance rate for denver airport is 80). This action is taken because (name) airlines schedules their arrs 30 mins before their own departures are scheduled to depart the gates. Arriving aircraft park in 'penalty box', as well as short runway 25 waiting for available gates. This 'parking problem' is passed on to the center via 'airborne delays' for those aircraft arriving den stapleton airport. On 2/92, I was the radar controller on sector 26, a low altitude arrival sector southwest of denver, co. Due to (name) airlines scheduling, I was holding aircraft at every available altitude, with more aircraft coming. Category B aircraft were requesting radar vectors out of the holding pattern and descent below the positive control area with intent to cancel IFR. These unnecessary airborne delays result in undue controller workload and sector complexity, and this is unfair to other users of the ATC system. Air carrier X, medium large transport was holding at shrew intersection at FL210. Air carrier Y, small transport was approaching the holding stack at FL210 with no available altitudes in the pattern. I issued control instructions to both aircraft, but not in time to avoid a loss of separation. These delays into denver on a VFR day can be avoided with a minor change in (name) airlines schedules.

Original NASA ASRS Text

Title: CTLR INVOLVED IN LTSS DUE TO ARR RUSH AND POOR AIRLINE SCHEDULE.

Narrative: AT APPROX XX30 MDT EVERY DAY, DENVER ARTCC TFC MGMNT UNIT (TME) IMPLEMENTS A REDUCED ARPT ACCEPTANCE RATE OF 60-65 ACFT PER HR. (NORMAL ACCEPTANCE RATE FOR DENVER ARPT IS 80). THIS ACTION IS TAKEN BECAUSE (NAME) AIRLINES SCHEDULES THEIR ARRS 30 MINS BEFORE THEIR OWN DEPS ARE SCHEDULED TO DEPART THE GATES. ARRIVING ACFT PARK IN 'PENALTY BOX', AS WELL AS SHORT RWY 25 WAITING FOR AVAILABLE GATES. THIS 'PARKING PROBLEM' IS PASSED ON TO THE CTR VIA 'AIRBORNE DELAYS' FOR THOSE ACFT ARRIVING DEN STAPLETON ARPT. ON 2/92, I WAS THE RADAR CTLR ON SECTOR 26, A LOW ALT ARR SECTOR SW OF DENVER, CO. DUE TO (NAME) AIRLINES SCHEDULING, I WAS HOLDING ACFT AT EVERY AVAILABLE ALT, WITH MORE ACFT COMING. CATEGORY B ACFT WERE REQUESTING RADAR VECTORS OUT OF THE HOLDING PATTERN AND DSCNT BELOW THE PCA WITH INTENT TO CANCEL IFR. THESE UNNECESSARY AIRBORNE DELAYS RESULT IN UNDUE CTLR WORKLOAD AND SECTOR COMPLEXITY, AND THIS IS UNFAIR TO OTHER USERS OF THE ATC SYS. ACR X, MLG WAS HOLDING AT SHREW INTXN AT FL210. ACR Y, SMT WAS APCHING THE HOLDING STACK AT FL210 WITH NO AVAILABLE ALTS IN THE PATTERN. I ISSUED CTL INSTRUCTIONS TO BOTH ACFT, BUT NOT IN TIME TO AVOID A LOSS OF SEPARATION. THESE DELAYS INTO DENVER ON A VFR DAY CAN BE AVOIDED WITH A MINOR CHANGE IN (NAME) AIRLINES SCHEDULES.

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.