An Air Carrier Crew began the BUF ILS23 and forgot that the localizer is unusable beyond 5 nm when north. So thinking that they were high they began a descent. A missed approach was executed after a low altitude alert from ATC.
Synopsis
An Air Carrier Crew began the BUF ILS23 and forgot that the localizer is unusable beyond 5 nm when north. So thinking that they were high they began a descent. A missed approach was executed after a low altitude alert from ATC.
Narrative
I was the Captain and Pilot Flying. I was being vectored by Buffalo; NY approach control from a right hand pattern to the ILS for runway 23 at Buffalo; NY Int'l Airport. The conditions were: moderate rain; pattern altitude winds of approximately 140\50kts; and moderate turbulence. While at 2300' MSL; I was given a vector of 200 to intercept the localizer; and cleared for the ILS approach to Runway 23. The left hand wind was too much for that heading to intercept the LOC in time. I saw a distance of 10NM on my FMS's progress page; and that I was well above the glide slope (or so I thought). There is a note on the approach page that the glide slope is unreliable beyond 5nm of the localizer. I failed to note that; and began a 700fpm descent to attempt to capture the glide slope from above because we were now clear of the clouds; and the rain was less. The First Officer advised me where we were off the localizer; (still right); and that the airfield was not in sight. At that point both the Flight Crew; and now Approach Control realized that the ILS approach was being incorrectly flown. Approach Control advised the Flight Crew that their altitude was too low (1700' MSL); told us to climb. We then executed a missed approach to the left with Approach Control issuing a vector of 140 and 2500' MSL. A left hand pattern was flown; and an approach and landing on runway 23 was uneventful.
Second reporter narrative
We briefed and set up for the ILS Runway 23 BUF. Weather conditions at the time were challenging. While on vectors; we were in and out of light to moderate rain and light to moderate turbulence. ATC gave us a final intercept heading of 200 degrees (final approach course 233 degrees) and told to maintain 2500 FT until established. Wind at 2500 FT was 140/50; and direct crosswind. As a result; the autopilot never fully established the aircraft on the localizer. The Captain had a correction to center up the localizer and at that time also noticed that we were above glideslope. He initiated a vertical speed descent to recapture glideslope. We descended to approximately 1700 FT MSL when we realized the approach didn't look right given our distance from threshold. In addition; approach issued an altimeter warning concurrently with action above. At this point; we discontinued the approach; climbed back to 2500 FT and requested vectors for another approach. Second approach was uneventful. The note on the BUF ILS Runway 23 states that the glideslope is unusable 5 degrees right of localizer. Even though it was briefed; the combination of the weather conditions and strong winds were enough of a distraction to miss the false glideslope capture. Luckily; other indications pointed to the fact that something was not right and we reacted early enough that safety was not compromised.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.