Narrative:

I don't really know the proper protocol for reporting something like this; but I strongly believe that something is dangerously wrong with the glide slope signal with the ILS approach at buffalo niagara international airport. Please allow me to explain. I was flying a B737 as a first officer circa 2009. Runway 23 was in use and the weather was marginal; at best. The freezing level was around 5000 feet and we were in instrument meteorological conditions (IMC). We were flying a B737 with a sp-77 autopilot. The captain and I were approaching buf from the south and we were getting radar vectors from buffalo approach control to intercept the localizer inbound to runway 23. The approach controller's last instructions were 'you are three miles from klump; cross klump at 2300 feet; fly heading 260 to join the localizer; cleared for the ILS runway 23 approach'. The captain and I acknowledged the instructions and configured the aircraft for landing. (Heading 260; altitude 2300; flaps 5; speed 180 KIAS; approach mode autopilot was armed). Shortly thereafter; we noticed that the localizer course started to come alive. Then; and for no apparent reason; the aircraft slowly started to pitch up as if to chase after the glideslope signal; and our airspeed started to slow. Shortly after we pitched up; I noticed that the glideslope signal was alive before the localizer was centered (somewhat normal). The captain noticed the discrepancy immediately and disengaged the autopilot and decided to 'hand fly' the aircraft. He asked me to verify that we had the appropriate frequency tuned in for the approach. I obliged and verified that we did have everything tuned in and identified. The captain maintained aircraft control all of the while. However; we both questioned what we were seeing with regard to the ILS approach and subsequently flew through the localizer course inbound. The captain told me to contact the approach controller and let them know that we were going to execute a missed approach. The controller acknowledged and gave us vectors back around to try again. This time; we came in from the north; everything was normal; and the approach and landing were uneventful. There was one thing that stood out to me that night. The approach controller asked us if there was a problem when we went missed. I told him that I thought that we had a problem with our autopilot and that it was telling us to climb when it wasn't supposed to. The controller responded to the effect that it happens a lot out there. I thought that that statement was odd. The ATIS stated that the glide slope was unreliable to the right of runway centerline; but we were on the left when all of this happened. I checked the NOTAMS earlier and there was no mention of this. I was ready to chock this whole experience up as 'one of those days' when the aircraft equipment is not cooperating with us. However; it happened to me again last night; two years later. Same runway; same instructions from approach; same location; this time; with a different autopilot (sp-177); a different airplane B737; and this time; I was the captain. We were cleared for the ILS runway 23 approach into buffalo. The weather was similar to what it was a few years ago. The aircraft pitched up and the airspeed slowed; but we had auto-throttles. I disengaged the autopilot and my first officer hand flew the approach visually. So; it is with this in mind that I am writing to you this email. I am not sure as to what direction we should go with this; but I definitely feel that we should put it out to the folks that are out flying the line.

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Original NASA ASRS Text

Title: A B737 Captain reported that the aircraft pitched up as the it approached the BUF Runway 23 localizer from the southeast even though the localizer is reported unusable 5 degree right of course.

Narrative: I don't really know the proper protocol for reporting something like this; but I strongly believe that something is dangerously wrong with the glide slope signal with the ILS Approach at Buffalo Niagara International Airport. Please allow me to explain. I was flying a B737 as a First Officer circa 2009. Runway 23 was in use and the weather was marginal; at best. The freezing level was around 5000 feet and we were in Instrument Meteorological Conditions (IMC). We were flying a B737 with a SP-77 autopilot. The Captain and I were approaching BUF from the south and we were getting radar vectors from Buffalo Approach Control to intercept the localizer inbound to RWY 23. The Approach Controller's last instructions were 'you are three miles from KLUMP; cross KLUMP at 2300 feet; fly heading 260 to join the localizer; cleared for the ILS runway 23 approach'. The Captain and I acknowledged the instructions and configured the aircraft for landing. (HEADING 260; ALTITUDE 2300; FLAPS 5; SPEED 180 KIAS; APPROACH Mode Autopilot was armed). Shortly thereafter; we noticed that the localizer course started to come alive. Then; and for no apparent reason; the aircraft slowly started to pitch up as if to chase after the glideslope signal; and our airspeed started to slow. Shortly after we pitched up; I noticed that the glideslope signal was alive before the localizer was centered (somewhat normal). The Captain noticed the discrepancy immediately and disengaged the autopilot and decided to 'hand fly' the aircraft. He asked me to verify that we had the appropriate frequency tuned in for the approach. I obliged and verified that we did have everything tuned in and identified. The Captain maintained aircraft control all of the while. However; we both questioned what we were seeing with regard to the ILS Approach and subsequently flew through the localizer course inbound. The Captain told me to contact the Approach Controller and let them know that we were going to execute a missed approach. The Controller acknowledged and gave us vectors back around to try again. This time; we came in from the North; everything was normal; and the approach and landing were uneventful. There was one thing that stood out to me that night. The Approach Controller asked us if there was a problem when we went missed. I told him that I thought that we had a problem with our autopilot and that it was telling us to climb when it wasn't supposed to. The Controller responded to the effect that it happens a lot out there. I thought that that statement was odd. The ATIS stated that the glide slope was unreliable to the right of runway centerline; but we were on the left when all of this happened. I checked the NOTAMS earlier and there was no mention of this. I was ready to chock this whole experience up as 'one of those days' when the aircraft equipment is not cooperating with us. However; IT HAPPENED TO ME AGAIN LAST NIGHT; two years later. Same Runway; same instructions from approach; same location; this time; with a different autopilot (SP-177); a different airplane B737; and this time; I was the Captain. We were cleared for the ILS RWY 23 Approach into Buffalo. The weather was similar to what it was a few years ago. The aircraft pitched up and the airspeed slowed; but we had auto-throttles. I disengaged the autopilot and my First Officer hand flew the approach visually. So; it is with this in mind that I am writing to you this email. I am not sure as to what direction we should go with this; but I definitely feel that we should put it out to the folks that are out flying the line.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.