As they neared the FAF; while 1;200 FT above the FAF glide slope crossing altitude; the flight crew of a BE400 was caught by surprise when the ceilings at BZN were lower than reported and they had to abandon their plan for a visual approach. When recleared to fly the Runway 12 ILS the pilot flying elected to attempt a straight-in (for which they had not been cleared) and a go around was necessary to permit them to fly the entire procedure as published.
Synopsis
As they neared the FAF; while 1;200 FT above the FAF glide slope crossing altitude; the flight crew of a BE400 was caught by surprise when the ceilings at BZN were lower than reported and they had to abandon their plan for a visual approach. When recleared to fly the Runway 12 ILS the pilot flying elected to attempt a straight-in (for which they had not been cleared) and a go around was necessary to permit them to fly the entire procedure as published.
Narrative
The weather at BZN was reported as 'Sky clear below 12;000 visibility 10 miles' 30 miles west of BZN we requested Direct MANNI to position the aircraft for a visual to Runway 12 and descended to 8;000. At 8;000 and 10 miles northwest of BZN we were still IMC in snow showers and so advised ATC. The Controller replied 'maintain 8;000 until MANNI cleared ILS Runway 12'. We were very close to MANNI and I understood that we would turn outbound over MANNI and fly the procedure turn. The flying pilot believed that we were cleared to join the approach course and fly inbound which he proceeded to do. I advised that we were required to turn outbound for the procedure turn but by the time this discussion occurred an outbound turn would have taken us well northeast of the course. We elected to fly the approach course to the Missed Approach point and miss the approach.Well before the Missed Approach Point we entered VMC conditions and were able to fly a Visual Traffic Pattern and land. Our expectation of a visual approach based on the weather reported and the frequency of radar vectors to ILS approaches led us to assume that one or the other would occur. We always tune and fly the ILS course and glide slope when one is available.This highlighted another habit pattern of selecting 'Direct FAF via VECTORS' on the FMS. This selection erases the IAFs from the display as well as the Procedure Turn depiction. We discussed this habit pattern and have agreed to delay selection until the intent of the Controller is clear. Unfortunately; current ATC procedures don't provide much advance notice as to whether you will be vectored to join or cleared to complete the course reversal as depicted. This information comes with the clearance for the approach and close to the course and the approach fix. We are changing our procedures to reduce the chances of this misunderstanding resulting from expectations of 'what usually happens'.
NASA callback
The reporter advised they had been cleared to contact the tower at the same time Center cleared them direct to the FAF. After turning inbound and finding themselves too high to safely complete the approach they contacted the Tower who was surprised to hear from them so soon; thus verifying the expectation that the intent of the original clearance included the expectation that; if they were not visual; they would have flown the course reversal.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.