Air carrier flight crew reported receiving a low altitude alert from Tower on approach to IAD.
Synopsis
Air carrier flight crew reported receiving a low altitude alert from Tower on approach to IAD.
Narrative
Began decelerate from 250 to 210 kts at UDIYU on the GIBBZ5 based on safety alert information. Approach then asked our speed and told us we should not have slowed. We maintained 210 kts at that point. As I had predicted; and the reason I began slowing; approach began to turn us base at about what would have meant an 8 mi final; and then said disregard. At what wound up to be about a 10 mi final; he turned us base at 4000 ft; then turned us dogleg and cleared us for the visual. I began a decelerate from 210 to 180 kts and asked for gear down; managed speed. Hand-flying now; I slowed to 180 and we configured flaps 2 and started a descent to 3000 ft. Almost 1000 ft high; I maintained gear down; flaps 2; and 180 kts to get down to the ILS glidepath. At 1500 ft; we were approximately 185 kts/gear down/flaps 2 but still high and then slightly overshot to approx 1/2 dot low at 1000 ft. At about this time; tower gave us an altitude alert at which time I noted ~1/2 dot low and PAPIs of 2 red; 1 pink; and 1 white. My reaction to tower's alert brought us slightly above glidepath; and the resulting decelerate allowed us to get flaps to full; on-speed and on vertical profile around 700 ft. While not desired and/or pretty; we were stabilized at 500 ft and made an uneventful landing.
Second reporter narrative
FLTXXXX descended via GIBZZ5 to bottom altitude with no airspeed restrictions. Absent further airspeed restrictions by ATC; and using info in company pages about short vectors to final; the PF on downwind slowed to 210 kts; ATC queried crew's airspeed and stated we were not to slow. At this point the crew was given a right turn and no lower altitude; so we maintained 4000 ft. The turn was a base leg to intercept final for IAD 19C. Next turn was clearance to intercept final; cleared visual approach 19C. There was no lower altitude provided. PF; while intercepting final around 10 miles from the runway and cleared the approach; slowed to 180 and requested gear and flaps 2. Being high; the PF descended to intercept GS while maintaining visual reference with the rwy. By 1500 ft agl the gear was down and 180 kts and we were still descending to intercept. As we were approaching 1000 ft the aircraft was intercepting GS but at the same time tower called a low altitude alert" and asked for us to confirm altitude and altimeter setting. Confirming position; altimeter; and speed I did not make the 1000 ft call but confirmed altimeter (2971 in) and cross referenced GS with rwy PAPIs. When call was made we were approx 1/2to 3/4 dot low on GS which was momentary due to the PF capturing GS and correcting. I did not see anything that would indicate an altitude that would constitute a low altitude call. At the same time the airspeed allowed for flaps 3 and then full flaps followed by landing checklist. These final steps were accomplished by 600 ft and the 500 ft callout was made to a "stable" response. Aircraft touchdown on speed within the TDZ."
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.