A320 Flight Crew reports programing the FMGC and briefing for the ILS 35R at DEN; including the correct frequency in the ND. After being cleared for the approach; problems develop and it is discovered that the correct ILS frequency is no longer displayed in the ND. Reinserting the ILS 35R in the FMGC corrects the problem.

Date: 2009-12 · Aircraft: A320

Anomalies: aircraft-equipment-problem-less-severe|deviation-track-heading-all-types

Synopsis

Narrative

With DEN approach anticipating clearance to Runway 35R we were descending to 9000 ft and slowing to 170 knots assigned. We were VFR but would be IFR on final. We had briefed the ILS approach to Runway 35R and verified it was selected and had the correct frequency on the Primary Flight Display (PFD). Heading 260 within 1 mile of intercept; First Officer who was flying said we need a turn just as ATC issued turn to 340 to intercept maintain 9000 ft to KORRY cleared approach to ILS 35R. I repeated clearance First Officer (FO) armed app and the Aircraft began to descend outside KORRY. FO got autopilot off and corrected within 150 ft back to 9000 ft. FO had called for flaps while that was happening so I was doing the flap selection to 2 flaps when ATC said I show you 10 degrees left of course turn to heading 010 to re-intercept. I looked at Navigation Display (ND) and it did show us to the left but the flight director was not giving correct info for the approach. First Officer disengaged auto pilot. I had the FO select raw data on the ND to fly the ILS while I reinserted 35R in the Flight Management Guidance Control (FMGC). I noticed that the PFD had 109.9 as the Ident and nothing else until I reinserted 35R again. It took the selection and we were able to stay stabilized on the approach crossing DEANE outside of final approach fix. We verified the FMGC info with the raw data and continued the approach. I don't know how or when the Ident on the PFD changed to 109.9 but neither of us selected that and we had earlier seen the correct frequency of 110.15. I did notice that my book of approach charts; which was on my table; partially blocked the bottom of the PFD.

Second reporter narrative

I was the pilot flying and with Denver Approach control for ILS to 35R. At our altitude; it was VFR; however; on the ground it was 1 NM -SN so ILS approaches were being conducted. The Captain and I briefed ILS 35R before the top of descent and verified the ILS frequency 110.15. During our descent; we were given a heading of 260 degrees and told to expedite to 9;000 ft. I disconnected the autopilot and was using the speed brakes in order to get down as we were also told to slow to 170 knots. On a 260 degree heading within 1 NM of the of final approach course; I said to the Captain; 'We need a turn inbound soon'. About that time; ATC told us to turn to a 340 degree heading to intercept the LOC for 35R. Almost immediately; ATC cleared us for the ILS approach and told us to maintain 9;000 ft until DORNY. The autopilot was reconnected and we both noticed that we did not yet have an identifier on either ND. The approach was armed; the aircraft captured the glide slope before intercepting the localizer and began to descend. I disconnected the autopilot and maintained 9;000 because we were still outside of Dorny. Because we were given a late turn inbound and with the wind blowing us away from course; according to our ND's we were showing a little left of course. ATC then said; 'I show you about 10 degrees left of course; turn to a 010 degree heading to re-intercept the localizer'. Both of our ND's showed the LOC course to our right which seemed correct; but both of our flight directors were not giving correct guidance to intercept the LOC. ATC said; 'Do you have the correct frequency tuned in?' Then we looked at our ND's and both showed the frequency 109.9; not 110.15 and with no identifier. We verified that ILS to Runway 35R was correctly installed and it was. The Captain said; 'Do you have raw data available?' and I replied; 'No; but I will get it.' I then hard-tuned 110.15 in the Rad Nav page and began flying raw data. It was still VFR and we were approaching DEANE (16.8 NM on ILS/DME 35R). I said to the Captain; 'Why don't you try changing the runway and then reinstalling ILS to 35R and see if the frequency corrects itself?' She did and then frequency 110.15 and its identifier IDPP appeared on both ND's which were correct. The FD's were now giving correct guidance and verification with raw data confirmed this so we continued the approach and the autopilot was reconnected. At this time we were not yet on the final approach segment. A normal stabilized approach was made to 35R without any further incident. Approach handed us off to Tower and a landing was made to Runway 35R without incident. I have flown the A319/A320 for 6 years and I have never experienced the ILS frequency being incorrect or changing after it was verified at the top of descent when the approach was briefed. When a runway is selected; the appropriate frequency is auto tuned without pilot input. We are then taught when close to the airport to verify that we get the correct identifier for the ILS frequency. From now on; after this incident; I am going to hard tune the ILS frequency on the Rad Nav page for backup and verification of the correct ILS frequency.

More incidents for this aircraft family →

Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.

← All incident reports Global safety overview