2022-07 · NASA ASRS report 1921092
Air Carrier flight crew reported confusing ATC clearance instructions on approach to DEN airport.
While on LAWGR 3 STAR Arrival into Denver landing Runway 17R; runway was changed to Runway 16L. Approximately 15 miles left base; we were asked if we had the airport and we responded we did; and were immediately cleared for the Visual Approach to Runway 16L and given a speed of at least 170 knots until a 5 mile final; or so we thought. We were under the impression that we were number one or had nobody within several miles in front of us due to shortcuts and very quick 'cleared for visual approach' while on approximately 10 mile final; while we were at a speed of 210 knots and ready to slow anyways; Approach Controller came back and told us with a firm voice that he needed 170 knots airspeed now. We mentioned we thought it was an airspeed of at least 170 knots; he only asked if we had the aircraft up ahead that was coming from the south and much lower on a right base in front of us for the same Runway 16 Left in sight. We responded affirmative we had that traffic in sight and would maintain visual separation and slowed to final approach speed immediately in landing configuration. He turned us over to Denver Tower at that time. Denver Tower approved an S-turn to the west and then had a plan B for us; in which they asked us to land 17R; we said OK and Denver Tower immediately cleared us to land on Runway 17R. We turned towards east towards 17R at that time. It was a visual approach as we had the runway clearly in sight. My First Officer was trying to put the localizer / ILS frequency in and program the FMC approach for 17R at that time and could not get rid of the ILS 16L. The Runway 17R is also approximately two miles further away (south) than runway 16L. This increased distance plus the additional S-turn distance caused us to be a little bit lower in altitude much further out than maybe we anticipated and created a perfect setup for an unstable approach and terrain warning which we received. Tower asked us if we had 17R in sight; we responded 'yes' and she cleared us to land again on 17R. We landed on 17R and proceeded to the gate without any further difficulty.
When given an airspeed of 170 knots to five miles; we flew faster than assigned. Confusion was between 170 knots or greater or hard 170. The question from Pilot Flying was not asked; and Pilot Monitoring did not question airspeed. We are still unsure of the actual phrasing given. Both pilots assumed we were number one for the field due to being given fix clearance limits closer and closer to the field. No traffic was called either from ATC; despite their being a regional on a right base to the same runway we were supposed to be following. Accepted a late runway change from Runway 16L to 17R and ended up getting landing flaps selected very late as well (25 to 30). Poor communication and crosscheck contributed to event. Radios were scratchy as well.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.
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