ATC confused, discretion descent clearance, on MD80 landing tus.

Attributes
ACN	574456
Time
Date	200302
Day	Fri
Local Time Of Day	0001 To 0600
Place
Locale Reference	airport : tus.airport
State Reference	AZ
Altitude	msl bound lower : 12000 msl bound upper : 29000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zab.artcc
Operator	common carrier : air carrier
Make Model Name	MD-80 Series (DC-9-80) Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : multi engine
Experience	flight time last 90 days : 50 flight time total : 8900 flight time type : 50
ASRS Report	574456
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : cfi pilot : atp pilot : multi engine
Experience	flight time last 90 days : 205 flight time total : 15900 flight time type : 3900
ASRS Report	574369
Events
Anomaly	other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : anomaly accepted
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance

Narrative:

Controller initially gave us descent to 12000 ft, apparently thinking we were inbound to phoenix. We were at FL290. Before leaving FL290, controller realized we were inbound for tucson instead. He then said 'if you want to stay at FL290 that's fine, discretion to FL270.' captain responded with readback. After handoff to new controller, captain checked in stating FL290 discretion FL270. Controller acknowledged. After departing FL290 for FL270, the controller queried our descent, not realizing the discretionary altitude. No conflicts. I believe the late hour helped attribute to the controller missing the discretionary altitude. Also, upon initial check-in, it took 3 attempts for ATC controller to acknowledge our check-in. I believe he was working multiple sectors and workload may have been another contributing factor. Again, no conflicts with other aircraft.

Original NASA ASRS Text

Title: ATC CONFUSED, DISCRETION DSCNT CLRNC, ON MD80 LNDG TUS.

Narrative: CTLR INITIALLY GAVE US DSCNT TO 12000 FT, APPARENTLY THINKING WE WERE INBOUND TO PHOENIX. WE WERE AT FL290. BEFORE LEAVING FL290, CTLR REALIZED WE WERE INBOUND FOR TUCSON INSTEAD. HE THEN SAID 'IF YOU WANT TO STAY AT FL290 THAT'S FINE, DISCRETION TO FL270.' CAPT RESPONDED WITH READBACK. AFTER HDOF TO NEW CTLR, CAPT CHKED IN STATING FL290 DISCRETION FL270. CTLR ACKNOWLEDGED. AFTER DEPARTING FL290 FOR FL270, THE CTLR QUERIED OUR DSCNT, NOT REALIZING THE DISCRETIONARY ALT. NO CONFLICTS. I BELIEVE THE LATE HR HELPED ATTRIBUTE TO THE CTLR MISSING THE DISCRETIONARY ALT. ALSO, UPON INITIAL CHK-IN, IT TOOK 3 ATTEMPTS FOR ATC CTLR TO ACKNOWLEDGE OUR CHK-IN. I BELIEVE HE WAS WORKING MULTIPLE SECTORS AND WORKLOAD MAY HAVE BEEN ANOTHER CONTRIBUTING FACTOR. AGAIN, NO CONFLICTS WITH OTHER ACFT.

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.