Regional Jet 200 ER/LR (CRJ200)
Flight Crew Air Transport Pilot (ATP)
Deviation - Altitude Overshoot; Deviation - Altitude Crossing Restriction Not Met; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Returned To Clearance; Flight Crew Became Reoriented
Aircraft; Human Factors
We were flying to MSP at our filed altitude of 14;000 feet; we were instructed to descend via the MUSCL2 RNAV arrival. We plugged in a 3 degree glideslope and verified that if we maintained 3 degrees we would make all crossing restrictions and arrive at our HARD limit of 8;000 feet and 230 kts at CMMOE. We briefed that we would descend at the 3 degree slope. The first officer was pilot flying and began his descent via the arrival. ATC then informed us that we had VFR traffic unverified at our 12 o'clock position and that he wanted us to level off at 10;000 feet. We dialed in 10;000 feet and leveled off at 10;000 feet. After a short time ATC instructed us that the traffic was no longer a factor. I asked the controller if he would like us to resume to 'descend via the arrival' and he said yes. The first officer then dialed in 8;000 feet into the altitude selector and called for the approach checklist. I performed the approach check flow and verified completion with the checklist. It was at this point that I noticed the First Officer had initiated his descent to 8;000 feet prior to crossing WDBRY at 10;000 feet and 250 kts. I called out 'altitude and that we should be at 10;000 feet still'. The first officer kind of froze so I quick hit the ALT button on the mode control panel so the plane would level off. I'm not 100 percent sure but I believe I hit the ALT button at about 9;600-9;700 feet and the plane descended as low as 9;500 feet before slightly climbing back to 9;700 ft. At this point we were very close to WDBRY and did not have time to climb back up to 10;000 before crossing so we held level at 9;700 feet as we crossed. We then descended to cross CMMOE at 8;000 feet and 230 kts per the arrival. The rest of the flight was uneventful. After landing and parking at the gate we debriefed what happened; what the contributing factors were; and how to prevent the re-occurrence. I believe that the First officer fully intended to meet all crossing restrictions properly. He just focused on making sure he crossed CMMOE at 8;000 and 230 kts that he forgot that he had to cross WDBRY at 10;000 feet. Fortunately the position that the descent was initiated was just prior to the crossing fix so that the deviation was minor and corrected fairly quickly and didn't create any traffic conflicts.I think the contributing factors were 1. Low familiarity and comfort level in the aircraft slightly decreasing situational positional awareness. (First Officer has only been on the line a couple months).2. Low familiarity with descend via arrivals.3. Being taken off the descend via clearance due to traffic and then being told to resume got the pilot flying a little out of sequence. 4. Event occurred at a time that I (pilot monitoring) was performing an approach flow and checklist.5. during the debrief we discussed 'descend via' procedures and techniques and I feel that maybe the First Officer didn't have a completely solid understanding of techniques and procedures to help ensure and safeguard that all crossing restrictions are met accurately. I feel like 'descend via the arrival' procedures have been an area that some pilots are struggling with and it is common to see a vast array of techniques that are used; (some successfully and some that are not) unfortunately it is common that the pilot monitoring may be distracted with checklists or preparing for the approach; especially if there was a runway change; during this period of heightened workload. During the debrief and discussion of the event with the First Officer I feel like we covered the event quite thoroughly and cleared up any confusion that might have been present.
On the arrival procedure (MUSCL TWO) into MSP there were crossing restrictions on the way down (the applicable ones were BAYKS (12000A/280); LOOON (11000A); WDBRY (10000A/250); ZASKY (9000A) CMMOE (8000/230). ALL altitudes were verified in the FMS between me and the Captain prior to executing the arrival. This was based on a 3 degree slope down. I began the descent early (about 1.5-2.0 degree slope) thinking it would just be a smoother descent. We met the first two altitude restrictions (BAYKS; LOOON) On the way down through 11;000 feet or so; we were told by MSP center that there was unidentified VFR traffic alert and we needed to stop our descent at 10;000 feet. We were unclear if we were being taken off the published arrival. We stopped at 10;000 feet. A minute or two later; we were told that the traffic is no factor and to proceed with the arrival. We then started down; again only at a 2 degree or so slope. It dawned on the captain that we were descending through 9;800 about 2 or 3 miles outside of WDBRY; which calls for at or above 10;000. I quick glanced at my arrival plate and realized this myself; and immediately programmed the FCP to level off. I leveled off around 9;500 feet and slowly brought the plane back up to around 9;700 feet just for the couple miles until WDBRY; after that the arrival called for at or above 9;000 at ZASKY as the next altitude restriction. After WDBRY; I programmed the FCP to continue down to meet the 9;000 feet restriction and realized that aircraft was not reacting to the turn coming up at ZASKY. The Flight Director was banking but the airplane was not turning.. I immediately disconnected the autopilot and banked the aircraft in the right turn towards CMMOE. I completed the turn a mile or so left of course. I did not take the plane off of NAV mode and have no idea how the aircraft ended up in another lateral mode. At this point the captain took the controls through standard calls. He got the aircraft back on course towards CMMOE and then transferred the controls back to me. Soon after this we received radar vectors for the visual approach to 12L. No comments about the deviations were made from ATC. We landed and taxied to the gate and successfully completed the flight. There was a breakdown in communication somewhere that resulted in the aircraft being in another lateral mode other than NAV (FMS). I don't know if the captain put it in another lateral mode and I didn't see it. The call from ATC with having us stop the descent distracted us and left us wondering if we were on vectors or not. The descent was planned and verified at a 3 degree descent and should have been executed that way. I should not have started down early in an attempt to have a more shallow descent. I then caused the aircraft to be 'below the glideslope' on the way down.
CRJ-200 reports missing a crossing restriction at WDBRY on the MUSCL2 arrival to MSP.