Air carrier flight crew reported they were cleared for the RNAV (GPS) Z runway 17 approach to mtj in...

Narrative:

Cleared by denver center for RNAV Z runway 17 in visual conditions; skies clear. We slowed down to follow other inbound traffic that center called out to us but we did not see. Inbound from bruuk and before widru a VFR [light transport] entered final in front of us from the west at widru. We were already at final approach speed and were catching up with him. As traffic got closer we felt we were too close to complete the approach and landing behind him and had concerns for climbing over him on a go around since his altitude seemed high for the approach at or near our same altitude. The first officer suggested we do a right 360 turn to rejoin and since we were in clear conditions; my brain mistakenly thought we were on a visual approach at that point but forgot that we were still on an IFR clearance. We neglected to contact denver center for clearance for a visual approach. Contributing factors were; numerous VFR traffic targets in the pattern at mtj; busy unicom radio calls. When we landed safely we then realized that we should have either called denver center immediately for a new visual approach clearance or just done the instrument approach missed approach procedure and then called denver center during the missed approach. I think both of our minds had reverted to the expectation bias that since it was severe clear during the approach we proceeded as if we were on a visual clearance. This all happened despite the fact that we read and briefed all the published information regarding montrose; no tower ops and mountain flying guide; together during cruise well before descent. I learned a lot from this situation including that I will now brief exactly what we will do and what is required if there is any kind of change or problem requiring a solution during any approach in non-tower operations. I have some experience flying into mountain no tower airports but this airport has a much higher volume of traffic involved. We felt it was a safer option to turn in a direction that kept us away from traffic on TCAS and visually. We made mistakes with the radio panel as well and had unicom on both radios.

Original NASA ASRS Text

Title: Air Carrier flight crew reported they were cleared for the RNAV (GPS) Z Runway 17 approach to MTJ in visual conditions. They deviated from their IFR clearance to avoid an aircraft on final without obtaining clearance for a visual approach from Denver Center.

Narrative: Cleared by Denver Center for RNAV Z Runway 17 in visual conditions; skies clear. We slowed down to follow other inbound traffic that center called out to us but we did not see. Inbound from BRUUK and before WIDRU a VFR [light transport] entered final in front of us from the west at WIDRU. We were already at final approach speed and were catching up with him. As traffic got closer we felt we were too close to complete the approach and landing behind him and had concerns for climbing over him on a go around since his altitude seemed high for the approach at or near our same altitude. The First Officer suggested we do a right 360 turn to rejoin and since we were in clear conditions; my brain mistakenly thought we were on a visual approach at that point but forgot that we were still on an IFR clearance. We neglected to contact Denver Center for clearance for a visual approach. Contributing factors were; numerous VFR traffic targets in the pattern at MTJ; busy Unicom radio calls. When we landed safely we then realized that we should have either called Denver Center immediately for a new visual approach clearance or just done the instrument approach missed approach procedure and then called Denver Center during the missed approach. I think both of our minds had reverted to the expectation bias that since it was severe clear during the approach we proceeded as if we were on a visual clearance. This all happened despite the fact that we read and briefed all the published information regarding Montrose; no tower ops and mountain flying guide; together during cruise well before descent. I learned a lot from this situation including that I will now brief exactly what we will do and what is required if there is any kind of change or problem requiring a solution during any approach in non-tower operations. I have some experience flying into mountain no tower airports but this airport has a much higher volume of traffic involved. We felt it was a safer option to turn in a direction that kept us away from traffic on TCAS and visually. We made mistakes with the radio panel as well and had Unicom on both radios.

Data retrieved from NASA's ASRS site 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.

Attributes
ACN	1336393
Time
Date	201602
Local Time Of Day	0601-1200
Place
Locale Reference	MTJ.Airport
State Reference	CO
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	Large Transport
Operating Under FAR Part	Part 121
Flight Phase	Final Approach
Flight Plan	IFR
Aircraft 2
Make Model Name	Light Transport
Flight Plan	VFR
Person 1
Function	Pilot Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 180 Flight Crew Total 15800 Flight Crew Type 598
Person 2
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 20 Flight Crew Total 10906 Flight Crew Type 4472
Events
Anomaly	Conflict Airborne Conflict Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Deviation - Track / Heading All Types

Air carrier flight crew reported they were cleared for the RNAV (GPS) Z runway 17 approach to mtj in visual conditions. They deviated from their IFR clearance to avoid an aircraft on final without obtaining clearance for a visual approach from denver center.