Narrative:

This event occurred on day 3 of a 3-day trip on; leg 2 of 3. The flight was to bhm. It was known that bhm had several pilot reports for turbulence and thunderstorms; as well as red tornado warning boxes on the radar. The captain was pilot flying; I was first officer and pilot monitoring. As we began our descent; we were given a lot of latitude from ATC to deviate as necessary; and we chose a path that took us northeast of bhm. The tops were around fl 350 and the light turbulence began there. From the mid-20s; we encountered light-to-moderate rain and light-to-moderate turbulence all the way until landing. We were high on the descent path most of the way down; and somewhere in the mid-teens; we had a close lighting and thunder encounter. (Although we don't believe we were hit; it was enough to get the flight attendants inquiring.) going through about 13;000' in moderate turbulence; I prompted the captain to slow down as we were still at about 280. Center and approach were accommodating in giving us direct wherever we wanted; which ultimately was a heading just outside the FAF (there was heavy precipitation near 10-15 mile final). As we neared the FAF; there was some confusion as to when the LNAV/VNAV scale on the pfd would change over to the localizer/G/south scale. It eventually did change over and we were able to configure in time. Moderate turbulence was reported on final; light-to-moderate rain was indicated on our radar; and winds were last reported as a direct crosswind of 150 at 16g24. (Just moments earlier; an ATIS report of winds 130 at 16g32 rendered runway 24 unusable for us until bhm approach issued the updated winds. This constant performance referencing and associated discussion added to the workload. Additionally; throughout the last 15 minutes of flight; it was noted on our radar that a strong cell was moving towards the airport. It appeared that we would get to the airport first; but that we might encounter it on a missed approach. (However; I honestly do not believe that this played a role in this event. It was just one more thing demanding our attention.) the captain flew the approach coupled with the autopilot; but not the autothrottles. (Other than practice GPS approaches; the captain had not used autothrottles for approaches during our trip.) approaching the FAF at flaps 25; there were two instances that I called airspeed as we came within a knot or two of flaps 25 placard speed (170). (Masi-25 was around 145 knots; v-target was 144.) FAF inbound to about 500' AGL went fairly well; albeit very bumpy with moderate rain and plus/minus 5-10 knots along the way. Sometime inside of 1000'; I selected wipers to high. (The captain was very busy with the approach; and I didn't bother asking.) sometime around 500'; I thought that I lost my flight director and localizer/glideslope inputs. I think I remember seeing cws P/cws right as well. I said; 'I lost it.' this got me to look outside where the runway was coming into view. Instinctively (though not necessarily correctly) I punched the appr button. When I looked back at my pfd; everything was back; and I called; 'approaching minimums.' I'm still very uncertain (and curious) as to what actually happened in those few moments; but it's hard to tell. Because of the earlier occurrences of coming near flap placard speed; I was also more focused on trying to ensure that we didn't exceed flaps 30 placard speed as the captain was flying a slightly fast approach (within limits; I believe); and with the gusts and turbulence; it was a blur. At minimums; the captain called landing and started to dive for the runway. It didn't immediately seem too steep to me; but we soon got; 'sink rate; sink rate' from the GPWS. I then noticed the glideslope more than a dot low; and called 'glideslope.' then; GPWS chimed in with; 'glideslope/glideslope.' (I don't recall hearing 'correcting' from the captain; but again; the memory is blurry.) at this point between 100-200'; ifelt looking out the windscreen that we would land on the pavement without a problem; and didn't order a go-around. We floated about 500' (guesstimate); and touched down softly about 300' short of the displaced threshold. When we got to the gate; I told the captain that I felt we erred and that I should have told him to go around once we got the warnings. His response was that he 'had it visually by that point.' I told him that we touched down shy of the displaced threshold. His reply was that he didn't see that; but that he was just trying to keep the airplane in the middle of the runway (and with that crosswind; I believe him!). I believe that once we reached minimums; the captain dove for the runway to get the airplane on the ground without situational awareness of the presence of a displaced threshold. Regardless of the 'whys'; a go-around should have been called for by me (pilot not flying) at any of the following points: 1) when I either lost my localizer/glideslope or my situational awareness (don't know which; but it had to be one of them!); 2) when we got sink rate; 3) when we got glide slope (though we could see that we were over the runway by that point); and 4) when it became apparent that there was a good chance we'd touch down shy of the displaced threshold (regardless of the fact that we were over the runway.) additionally; the captain should have gone around when he got the sink rate warnings with or without my intervening. There were many contributing factors here. Weather was clearly the main one; failure to adhere to policy was another; and perhaps even unfamiliarity with the displays was a factor; too. When we departed runway 24 two hours later (after the storms moved through); I could see the reason for the displaced threshold. It was a berm just shy of runway 24. I certainly didn't see that on approach in the rain; and I'm curious if we came close to it.

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Original NASA ASRS Text

Title: A Flight Crew reported a turbulent and windy approach to BHM in low visibility and questioned whether a missed approach should have been initiated because of Sink Rate and Glide Slope warnings. The aircraft landed in the overrun short of the threshold without damage.

Narrative: This event occurred on day 3 of a 3-day trip on; leg 2 of 3. The flight was to BHM. It was known that BHM had several pilot reports for turbulence and thunderstorms; as well as red tornado warning boxes on the radar. The Captain was pilot flying; I was First Officer and pilot monitoring. As we began our descent; we were given a lot of latitude from ATC to deviate as necessary; and we chose a path that took us northeast of BHM. The tops were around FL 350 and the light turbulence began there. From the mid-20s; we encountered light-to-moderate rain and light-to-moderate turbulence all the way until landing. We were high on the descent path most of the way down; and somewhere in the mid-teens; we had a close lighting and thunder encounter. (Although we don't believe we were hit; it was enough to get the Flight Attendants inquiring.) Going through about 13;000' in moderate turbulence; I prompted the Captain to slow down as we were still at about 280. Center and Approach were accommodating in giving us direct wherever we wanted; which ultimately was a heading just outside the FAF (there was heavy precipitation near 10-15 mile final). As we neared the FAF; there was some confusion as to when the LNAV/VNAV scale on the PFD would change over to the LOC/G/S scale. It eventually did change over and we were able to configure in time. Moderate turbulence was reported on final; light-to-moderate rain was indicated on our radar; and winds were last reported as a direct crosswind of 150 at 16G24. (Just moments earlier; an ATIS report of winds 130 at 16G32 rendered Runway 24 unusable for us until BHM Approach issued the updated winds. This constant performance referencing and associated discussion added to the workload. Additionally; throughout the last 15 minutes of flight; it was noted on our radar that a strong cell was moving towards the airport. It appeared that we would get to the airport first; but that we might encounter it on a missed approach. (However; I honestly do not believe that this played a role in this event. It was just one more thing demanding our attention.) The Captain flew the approach coupled with the autopilot; but not the autothrottles. (Other than practice GPS approaches; the Captain had not used autothrottles for approaches during our trip.) Approaching the FAF at flaps 25; there were two instances that I called airspeed as we came within a knot or two of flaps 25 placard speed (170). (MASI-25 was around 145 knots; V-target was 144.) FAF inbound to about 500' AGL went fairly well; albeit very bumpy with moderate rain and plus/minus 5-10 knots along the way. Sometime inside of 1000'; I selected wipers to high. (The Captain was very busy with the approach; and I didn't bother asking.) Sometime around 500'; I thought that I lost my Flight Director and LOC/glideslope inputs. I think I remember seeing CWS P/CWS R as well. I said; 'I lost it.' This got me to look outside where the runway was coming into view. Instinctively (though not necessarily correctly) I punched the APPR button. When I looked back at my PFD; everything was back; and I called; 'Approaching minimums.' I'm still very uncertain (and curious) as to what actually happened in those few moments; but it's hard to tell. Because of the earlier occurrences of coming near flap placard speed; I was also more focused on trying to ensure that we didn't exceed flaps 30 placard speed as the Captain was flying a slightly fast approach (within limits; I believe); and with the gusts and turbulence; it was a blur. At minimums; the Captain called landing and started to dive for the runway. It didn't immediately seem too steep to me; but we soon got; 'Sink Rate; Sink Rate' from the GPWS. I then noticed the glideslope more than a dot low; and called 'Glideslope.' Then; GPWS chimed in with; 'Glideslope/Glideslope.' (I don't recall hearing 'correcting' from the Captain; but again; the memory is blurry.) At this point between 100-200'; Ifelt looking out the windscreen that we would land on the pavement without a problem; and didn't order a go-around. We floated about 500' (guesstimate); and touched down softly about 300' short of the displaced threshold. When we got to the gate; I told the Captain that I felt we erred and that I should have told him to go around once we got the warnings. His response was that he 'had it visually by that point.' I told him that we touched down shy of the displaced threshold. His reply was that he didn't see that; but that he was just trying to keep the airplane in the middle of the runway (and with that crosswind; I believe him!). I believe that once we reached minimums; the Captain dove for the runway to get the airplane on the ground without situational awareness of the presence of a displaced threshold. Regardless of the 'whys'; a go-around should have been called for by me (pilot not flying) at any of the following points: 1) when I either lost my LOC/glideslope or my situational awareness (don't know which; but it had to be one of them!); 2) when we got Sink Rate; 3) when we got Glide Slope (though we could see that we were over the runway by that point); and 4) when it became apparent that there was a good chance we'd touch down shy of the displaced threshold (regardless of the fact that we were over the runway.) Additionally; the Captain should have gone around when he got the Sink Rate warnings with or without my intervening. There were many contributing factors here. Weather was clearly the main one; failure to adhere to policy was another; and perhaps even unfamiliarity with the displays was a factor; too. When we departed Runway 24 two hours later (after the storms moved through); I could see the reason for the displaced threshold. It was a berm just shy of Runway 24. I certainly didn't see that on approach in the rain; and I'm curious if we came close to it.

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.