Air carrier flight crew reported an altitude alert from ATC while on approach to AMA airport.
Synopsis
Air carrier flight crew reported an altitude alert from ATC while on approach to AMA airport.
Narrative
On approach to Runway 4 in AMA. Approach offered visual Runway 4. We did not have airport in site. We asked for the full RNAV approach instead of the visual. Due to unfamiliarity with the airport and nighttime conditions. We were then given vectors and Approach asked us to turn base at the final approach fix. I said unable as this did not seem to be a safe option with a newer First Officer (FO) flying I asked for the full RNAV. We were given downwind X past the final approach fix. And to descend to 5;200 ft. We were turned base at the initial fix I noticed the aircraft getting slow and informed the pilot monitoring we needed flaps 9. I informed him to increase speed slightly. I became focused on the airspeed and did not notice him starting to descend at the IF below 5;200 ft. At approximately 4;900 ft. Tower informed us that we were too low at which point I looked at altitude and took the controls to increase altitude and airspeed. Then turned off Autopilot and I returned the plane to 5;200 ft. as we were still not at the final approach fix yet. I then called for gear down and flaps 22 approximately 1.5 miles from the final approach fix. And flaps 45 slightly under a mile from final approach fix as the plane had slowed below 155 kts. After plane was stable and flaps 45 I returned controls to the FO and continued monitoring. We were then given clearance to land by the Tower and landed without incident.I became fixated on the airspeed as we had gotten slow during part of the approach. We were still with speed limits but I still felt it was to slow for my liking. I will make sure to keep my scan up and not get fixated on one thing. If I had not been fixated on speed I would have noticed the early descent.
Second reporter narrative
On approach for Runway 4 we were given headings to intercept at the FAF. We asked immediately to be given vectors to the IF point since it was getting dark and the airport was not familiar. We received a different heading and were told to decent to 5;200 ft. As soon as we received our clearance for the RNAV 4 I pressed the NAV after turning to intercept the approach. While the localizer was intercepted I noticed that the Vertical Path Indicator (VPI) was below and therefore I started my descent to ensure that we are not too high. As soon as the aircraft descended the VPI jumped back up in position; and the Tower informed us that we are too low. Captain took control of the aircraft and went back up to 5;200 ft. while disconnecting the Autopilot and getting back on the glide path since the airport had been visible. The weather was calm and visibility was 10 SM. Captain requested gear down; flaps 22; and flaps 45 landing checklist. After the approach was stable; the Captain gave control back to me and I finished landing the aircraft.I will make sure that I communicate if I see the VPI on RNAV approaches going below with the Captain prior to starting the descent as well as ensure that I double-check on the plate what altitudes I should be at while reaching fixes on the approach. I will also be more cognizant of my speed.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.