Corporate flight crew reported crossing approach fix below published altitude resulted in ATC alert as crew continued on visual approach.
Synopsis
Corporate flight crew reported crossing approach fix below published altitude resulted in ATC alert as crew continued on visual approach.
Narrative
Description: Possible altitude deviation across the final approach; fix in VMC conditions; although cleared for a localizer approach.Identification: I was unaware that we had dropped below the published altitude until we landed.Cause: Doing a reposition flight from ZZZ to Aspen. We had extensively briefed the departure and the possible routes ATC could give us between ZZZ and Aspen in addition to what we could receive as a clearance. we spent a great deal of time discussing the step down fixes on the localizer DME E approach and what would be done once clear of the scattered layer that was advertised at Aspen. We discussed how to configure the airplane; speeds and then decent rates after the last ridge prior to doing a visual descent to capture the PAPI. Denver Center had us fly to red table at 17;000 feet; but prior to turning us over to Aspen Approach we were told to expect direct to JARGU with a descent to 13;000. We returned over to Aspen Approach who cleared us to Jargo at 13;000 and shortly thereafter cleared us for the localizer approach. Airplane configuration and speed adjustment happened early and we started the approach fully configured and on speed as the approach progressed; I was setting step down altitudes monitoring what the other pilot was doing and answering radio calls as well as ultimately changing frequencies ATC prior to the handoff to Aspen Tower asked me to monitor cloud bases and report those as we cleared the clouds. After setting the last step down altitude for DOYPE I had time to glance at the Primary Flight Display (PFD) and was satisfied that everything was on track. I then glanced outside to determine where the cloud bases were and noticed that as we crossed FIMSO we were below all clouds and had visually acquired the runway; but we still had some ragged bases to our west. I got busy setting and changing frequencies to talk to Aspen Tower; but failed to remember to report that we were visual so that we could receive the visual approach. I failed to notice that we had dropped below; the published altitude at DOYPE but checked with the flying pilot to make sure he had visually acquired the runway and was comfortable with his approach. No unusual descent rates were required to fly this visual descent to the 4 mile fix where the pappy guidance was used to the runway.Response: I realized that my mistake was task saturation; and although I had called a cloud base that was below the DOYPE altitude; I called it only because I was busy; and I reported the lowest of the ragged bases to the west of the airport. I had failed to call the visual conditions when I saw them at FIMSO and thus did not receive a visual clearance; which would allow us to cross the final at a lower altitude. Task saturation was my primary problem. I should've paid closer attention to where we were in space to the approach not relative to the terrain which I'd become my primary focus. Suggestions: Although we had thoroughly briefed all aspects of this approach; it's always a guessing game how Aspen is going to bring us onto the specific approach they advertise. In the recent past all my approaches into Aspen have been from a left downwind and extensive vectors of this. We briefed both shortcuts and the downwind approach; focusing on published altitudes for the initiation of the approach. My workload was increased a bit when we were vectored in lower than the 13;400 foot initial altitude so my monitoring of the pilot flying's (PF's) use of the Autopilot took me away from what I should have been doing. The training environment is also somewhat more hectic and as I mentioned my primary focus needs to become strictly adhering to the approach assigned. I also feel that because our aircraft are not certified for the actual glide path required for these approaches; and since we consider our descent from the mist approach point to the runway; visual descent; rather than an approach; we could clarify this a great deal setting up our airplanes to comply with appendix 10; and training that actual approach. I feel this would not only have helped my situation; but would also eliminate a lot of the variations on the theme that we have happening in Aspen. Interestingly; they redid their ATIS to advertise that pilots needed to remember to call visual conditions as soon as they got them so they could be given the visual approach -that would've helped me remember to do so!
Second reporter narrative
Description: On Day 0; I was the pilot flying; acting as the First Officer; on a reposition flight from ZZZ to Aspen; CO. It should be noted that this flight was a training flight as a part of my Initial Operator Experience (IOE).Prior to our departure; the Captain and I conducted a thorough briefing in accordance with company SOPs. We addressed the potential challenges expected during the flight; such as my lack of familiarity with Aspen and the significant descent angle required once we entered VFR conditions. We determined that the weather was good enough to fly into Aspen; however; we would need to fly an instrument approach to get below the cloud layer. We briefed the LOC/DME-E approach to include the various fixes and their crossing altitudes. We discussed that once we reached DOYPE at 11;700 ft MSL that we would be required to descend at a descent angle greater than 6 degrees. We discussed that we would need to be prompt in our descent in order to be stabilized during our final approach to landing.We departed ZZZ at approximately XA:55 on an IFR flight plan and were provided a clearance up to 17;000 feet. As we neared the Aspen area; we were cleared to descend to 13;000 feet. We were then provided vectors to intercept JARGU and then cleared for the LOC/DME-E approach. As we began the approach; using the Autopilot for guidance; we were very diligent in using the Autopilot altitude selector to select the appropriate crossing altitudes as briefed during our approach briefing. After crossing FIMSO at 12;300 ft we set the altitude selector to 11;700 ft; which is the final crossing restriction at DOYPE. Prior to reaching DOYPE we descended below the cloud layer and entered visual flight conditions. The Captain; who was the pilot monitoring; asked if I had the airfield insight. I confirmed with the Captain that I had the airfield insight and he instructed me to disconnect the Autopilot and begin my steeper than normal descent as briefed prior to departure. A short time later; the controller asked if we had Aspen in sight. We confirmed that we did and were cleared for the visual approach as well as cleared to land.I was unaware that we had violated any crossing restrictions. It was our belief that we had complied with all crossing restrictions.The Captain and I discussed this incident in detail in an attempt to figure out how this inadvertent error occurred. We determined that due to the high workload; compounded by the training nature of this flight; we had momentarily lost situational awareness and believed that we had passed DOYPE prior to commencing our steep descent angle and descending below 11;700 ft. It should be noted that our error did not cause any terrain or traffic collision warnings to be depicted on our flight guidance systems.Cause: As previously mentioned; we believe that the one of the main contributing factors of this altitude deviation was high workload; compounded by the training nature of this flight. Due to those reasons; we had momentarily lost situational awareness and believed that we had passed DOYPE prior to commencing our steep descent angle and descending below 11;700 ft. Response: Once we were made aware of the deviation; the captain and I discussed in detail the approach. We spoke about what we felt the contributing factors were in an attempt to learn from this incident.Suggestions: One suggestion that I have would be to integrate flying an approach into Aspen during our initial type ratings. As a part of my initial type training; we practice alternate departure procedures out of the Aspen airport. Due to the unique nature of this instrument approach; it would be helpful to have practice the approach during the same session as the departure procedure.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.