Commuter inbound on DME arc descends from assigned altitude.

Attributes
ACN	135615
Time
Date	199002
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : fmn
State Reference	NM
Altitude	msl bound lower : 10300 msl bound upper : 11000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdv
Operator	common carrier : air carrier
Make Model Name	Small Transport, Low Wing, 2 Turboprop Eng
Flight Phase	descent : approach
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
ASRS Report	135615
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : commercial pilot : atp
Experience	flight time last 90 days : 280 flight time total : 3000
ASRS Report	135399
Events
Anomaly	altitude deviation : excursion from assigned altitude other anomaly other
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Flight was inbound from the northwest to farmington, NM to the VOR. We were expecting the ILS runway 25. Approximately 25 DME out the controller asked if we could take the approach to VOR runway 7 instead. We stated that we could. While changing approach plates the controller gave us a heading of 180 degrees. After the new heading the flight duties were switched, and the controls of the aircraft were transferred to the first officer. Then the controller stated something about holding at wilde intersection, then said disregard and fly heading of 160 degrees and descend to 11000' and proceed to the 16 DME arc for VOR runway 7. Moments later the arc was intercepted and I was maneuvering to panel the arc. At this time the controller gave out more information. Maneuvering the aircraft and checking my position to the approach chart I was not listening carefully. As I rolled out on the arc and well past the IAF, I thought I heard the controller clear us. I began a descent as published on the chart. Going through approximately 10700' the captain questioned my descent. I then stated we were cleared for the approach. He said he would double-check on it. At that time the controller questioned our altitude. We stated we were now at 10300'. The controller stated assigned altitude was 11000', then cleared us to 10000'. Not until the turn inbound were we cleared for the approach, at which time we were 2000' higher than published. We dived down to the approach and shortly broke out and were able to make a smoother descent and approach visually. I believe that the problem occurred in that the controller was vectoring us and apparently unsure what to do next with us--and also at that time flight duties were switched, and between the two, confusion existed in the cockpit. Something should have been stated on what to expect. We were past the IAF and what would have happened if we had a radio failure, since we were inbound on the approach but not yet cleared.

Original NASA ASRS Text

Title: COMMUTER INBOUND ON DME ARC DESCENDS FROM ASSIGNED ALT.

Narrative: FLT WAS INBND FROM THE NW TO FARMINGTON, NM TO THE VOR. WE WERE EXPECTING THE ILS RWY 25. APPROX 25 DME OUT THE CTLR ASKED IF WE COULD TAKE THE APCH TO VOR RWY 7 INSTEAD. WE STATED THAT WE COULD. WHILE CHANGING APCH PLATES THE CTLR GAVE US A HDG OF 180 DEGS. AFTER THE NEW HDG THE FLT DUTIES WERE SWITCHED, AND THE CONTROLS OF THE ACFT WERE TRANSFERRED TO THE F/O. THEN THE CTLR STATED SOMETHING ABOUT HOLDING AT WILDE INTXN, THEN SAID DISREGARD AND FLY HDG OF 160 DEGS AND DSND TO 11000' AND PROCEED TO THE 16 DME ARC FOR VOR RWY 7. MOMENTS LATER THE ARC WAS INTERCEPTED AND I WAS MANEUVERING TO PANEL THE ARC. AT THIS TIME THE CTLR GAVE OUT MORE INFO. MANEUVERING THE ACFT AND CHKING MY POS TO THE APCH CHART I WAS NOT LISTENING CAREFULLY. AS I ROLLED OUT ON THE ARC AND WELL PAST THE IAF, I THOUGHT I HEARD THE CTLR CLR US. I BEGAN A DSCNT AS PUBLISHED ON THE CHART. GOING THROUGH APPROX 10700' THE CAPT QUESTIONED MY DSCNT. I THEN STATED WE WERE CLRED FOR THE APCH. HE SAID HE WOULD DOUBLE-CHK ON IT. AT THAT TIME THE CTLR QUESTIONED OUR ALT. WE STATED WE WERE NOW AT 10300'. THE CTLR STATED ASSIGNED ALT WAS 11000', THEN CLRED US TO 10000'. NOT UNTIL THE TURN INBND WERE WE CLRED FOR THE APCH, AT WHICH TIME WE WERE 2000' HIGHER THAN PUBLISHED. WE DIVED DOWN TO THE APCH AND SHORTLY BROKE OUT AND WERE ABLE TO MAKE A SMOOTHER DSCNT AND APCH VISUALLY. I BELIEVE THAT THE PROB OCCURRED IN THAT THE CTLR WAS VECTORING US AND APPARENTLY UNSURE WHAT TO DO NEXT WITH US--AND ALSO AT THAT TIME FLT DUTIES WERE SWITCHED, AND BTWN THE TWO, CONFUSION EXISTED IN THE COCKPIT. SOMETHING SHOULD HAVE BEEN STATED ON WHAT TO EXPECT. WE WERE PAST THE IAF AND WHAT WOULD HAVE HAPPENED IF WE HAD A RADIO FAILURE, SINCE WE WERE INBND ON THE APCH BUT NOT YET CLRED.

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.