Air carrier crew concerned about approach clearance issued by ZLC on approach to mso.

Attributes
ACN	431090
Time
Date	199903
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : mso.airport
State Reference	MT
Altitude	msl bound lower : 9500 msl bound upper : 10000
Environment
Flight Conditions	Mixed
Weather Elements	Snow
Light	Dawn
Aircraft 1
Controlling Facilities	artcc : zlc.artcc
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	other vortac
Flight Phase	descent : approach
Route In Use	approach : instrument non precision
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : private
Experience	flight time last 90 days : 240 flight time total : 13000 flight time type : 950
ASRS Report	431090
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial
Events
Anomaly	other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : unable
Supplementary
Problem Areas	Flight Crew Human Performance ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	other

Narrative:

Requested VOR DME-a approach to mso via 13 DME arc. Controller came back with, 'maintain 10000 ft until intercepting arc, cleared as requested.' at 13 DME, we began descent to 9100 ft, which was the initial altitude that was on the 13 DME arc. At about 9500 ft controller said, 'I show you established on the arc, cleared for the approach.' it was our understanding that we were already cleared for the approach. Conflict was: did we start our descent out of 10000 ft before we actually had clearance to do so?

Original NASA ASRS Text

Title: ACR CREW CONCERNED ABOUT APCH CLRNC ISSUED BY ZLC ON APCH TO MSO.

Narrative: REQUESTED VOR DME-A APCH TO MSO VIA 13 DME ARC. CTLR CAME BACK WITH, 'MAINTAIN 10000 FT UNTIL INTERCEPTING ARC, CLRED AS REQUESTED.' AT 13 DME, WE BEGAN DSCNT TO 9100 FT, WHICH WAS THE INITIAL ALT THAT WAS ON THE 13 DME ARC. AT ABOUT 9500 FT CTLR SAID, 'I SHOW YOU ESTABLISHED ON THE ARC, CLRED FOR THE APCH.' IT WAS OUR UNDERSTANDING THAT WE WERE ALREADY CLRED FOR THE APCH. CONFLICT WAS: DID WE START OUR DSCNT OUT OF 10000 FT BEFORE WE ACTUALLY HAD CLRNC TO DO SO?

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.