Narrative:

While on arrival an hour prior to landing; I (pm) retrieved the ATIS and the performance west&B for a south landing. Coming from the west; I figured 20R was the obvious choice of runway and with the current weather conditions on the field; I assumed we would be doing the ILS to 20R. As nearly the entire flight was a sterile cockpit except a few conversations about turbulence and weather; I had set myself up for the ILS to 20R and waited for the captain to brief it. As we approached the top of descent; the captain stated that he was planning the rnp Z to 20L and told me that he wanted me to request that with approach. He briefed the approach; we discussed a few details about rnp value to input and accomplished the descent checklist. The captain; for some reason; seemed adamant about landing on the left side.when I checked in with approach; I gave him our request. Their reply was; 'you can expect 20L. I'll have to see about the rnp approach.' figuring we would not get the rnp approach; I went ahead and tuned in the ILS frequency on my side to 20L. As we entered the downwind; approach said they were unable the rnp approach; plan the ILS. The captain then briefed the ILS approach to 20L. As we were being vectored; we were going in and out of heavy rain and turbulence. As we were getting close to turning base leg; approach came on the frequency and stated that the braking action for runway 20L was reported poor by a 737. Approach then told another aircraft to plan runway 20R. The captain was adamant to me he still wanted runway 20L. Approach called us on our base leg to 20L and restated the braking action for 20L was poor and to turn to a heading and intercept the localizer to 20R and gave us the frequency. The captain went heads down in the FMC to program the approach. At this point; I already had the frequency in standby on my side so I switched the frequency; then turned to my ipad to pull up the approach. As this was all taking place; we were cleared to 2000 ft; cleared for the ILS; and handed off to tower. As we continued; the captain was calling for flaps and trying to quickly configure the airplane while I was contacting tower. I noticed the captain had LNAV engaged on the panel; so I was assuming he was intercepting the localizer course with that. The next thing I knew; we blew through the localizer and the captain had clicked off the autopilot and was rejoining. At this same time; tower stated that he showed us left of course. I stated that we were correcting. The captain then reengaged the autopilot and was still configuring the airplane. While all this was going on; I'm still trying to reset the baro for the minimums and the next thing I know; the captain turned off the autopilot again. While I was looking to try to double check his frequency; tower said they were showing us off course and I believed he asked us if we wanted to go around.the captain stated to me; 'I've got it now;' so I assumed that meant he had the localizer and the GS captured. So while I'm looking at my pfd; I'm relaying to ATC that we got it. By the time I was done with my transmission to ATC; the captain was diving the aircraft to the ground I saw at least a 1500 fpm descent all at the same time my localizer guidance was gone. I heard sink rate; and I told the captain to go around. ATC is calling us saying they have a low altitude alert; go around; and I hear caution terrain; too low terrain; pull up. I'm now yelling at the captain to 'go around pull up!' I'm grabbing for the controls because I don't see him reacting. My display now has red terrain on it and I don't have any lateral guidance on my flight director. The captain said he was going around and told me he was climbing. Tower then told us to climb to 3000 ft and gave us a heading. We still don't have any lateral guidance and heading mode won't engage. We finally get the aircraft stable; cleaned up on the right heading; and the captain was now telling me I want 20L. I request 20L and then I have to listen to ATC telling us about the same braking action report on 20L and when they say poor; the captain is saying 4. Then the captain wants to argue out loud with me about he's saying '4' not 'poor'. I go ahead and just start briefing the ILS approach to 20L and making sure all the captain was doing was flying the airplane. I programmed the FMC; made sure we both had the right frequency; and then landed without incident. The braking action was good. When we got to the gate; the captain apologized for putting us in that position.I believe ATC put us in a bad position by not giving us a choice or time to make a decision. By turning us and clearing us for an approach we were not prepared for; this put us immediately into the red. Even though he was trying to be helpful by giving us the localizer frequency; there was not enough time to brief and make sure we were prepared to fly the approach in IMC conditions. We failed to recognize the threat and stop the approach right there. With the current weather conditions being an additive; I\'m sure getting on the ground was a priority rather than getting beat up by the turbulence and heavy rain with extended vectors. I was immediately overloaded by changing frequencies; talking to tower; and trying to configure the aircraft and pull up the right approach plate on my ipad. Then with the distraction of flying through the localizer; the captain disconnecting the autopilot; and hand flying; I never finished what I was doing.

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Original NASA ASRS Text

Title: B737 flight crew reported that during a rapid descent in IMC they flew through the localizer and received several warnings in rapid order 'SINK RATE'; 'TOO LOW TERRAIN'; and 'PULL UP'.

Narrative: While on arrival an hour prior to landing; I (PM) retrieved the ATIS and the Performance W&B for a south landing. Coming from the west; I figured 20R was the obvious choice of runway and with the current weather conditions on the field; I assumed we would be doing the ILS to 20R. As nearly the entire flight was a sterile cockpit except a few conversations about turbulence and weather; I had set myself up for the ILS to 20R and waited for the Captain to brief it. As we approached the top of descent; the Captain stated that he was planning the RNP Z to 20L and told me that he wanted me to request that with approach. He briefed the approach; we discussed a few details about RNP value to input and accomplished the descent checklist. The Captain; for some reason; seemed adamant about landing on the left side.When I checked in with Approach; I gave him our request. Their reply was; 'You can expect 20L. I'll have to see about the RNP approach.' Figuring we would not get the RNP approach; I went ahead and tuned in the ILS frequency on my side to 20L. As we entered the downwind; Approach said they were unable the RNP approach; plan the ILS. The Captain then briefed the ILS approach to 20L. As we were being vectored; we were going in and out of heavy rain and turbulence. As we were getting close to turning base leg; Approach came on the frequency and stated that the braking action for Runway 20L was reported poor by a 737. Approach then told another aircraft to plan runway 20R. The Captain was adamant to me he still wanted Runway 20L. Approach called us on our base leg to 20L and restated the braking action for 20L was poor and to turn to a heading and intercept the LOC to 20R and gave us the frequency. The Captain went heads down in the FMC to program the approach. At this point; I already had the frequency in standby on my side so I switched the frequency; then turned to my iPad to pull up the approach. As this was all taking place; we were cleared to 2000 ft; cleared for the ILS; and handed off to Tower. As we continued; the Captain was calling for flaps and trying to quickly configure the airplane while I was contacting Tower. I noticed the Captain had LNAV engaged on the panel; so I was assuming he was intercepting the LOC course with that. The next thing I knew; we blew through the LOC and the Captain had clicked off the autopilot and was rejoining. At this same time; Tower stated that he showed us left of course. I stated that we were correcting. The Captain then reengaged the autopilot and was still configuring the airplane. While all this was going on; I'm still trying to reset the baro for the minimums and the next thing I know; the Captain turned off the autopilot again. While I was looking to try to double check his frequency; Tower said they were showing us off course and I believed he asked us if we wanted to go around.The Captain stated to me; 'I've got it now;' so I assumed that meant he had the LOC and the GS captured. So while I'm looking at my PFD; I'm relaying to ATC that we got it. By the time I was done with my transmission to ATC; the Captain was diving the aircraft to the ground I saw at least a 1500 fpm descent all at the same time my LOC guidance was gone. I heard sink rate; and I told the Captain to go around. ATC is calling us saying they have a low altitude alert; go around; and I hear CAUTION TERRAIN; TOO LOW TERRAIN; PULL UP. I'm now yelling at the Captain to 'GO AROUND PULL UP!' I'm grabbing for the controls because I don't see him reacting. My display now has red terrain on it and I don't have any lateral guidance on my flight director. The Captain said he was going around and told me he was climbing. Tower then told us to climb to 3000 ft and gave us a heading. We still don't have any lateral guidance and HDG mode won't engage. We finally get the aircraft stable; cleaned up on the right heading; and the Captain was now telling me I WANT 20L. I request 20L and then I have to listen to ATC telling us about the same braking action report on 20L and when they say poor; the Captain is saying 4. Then the Captain wants to argue out loud with me about he's saying '4' not 'poor'. I go ahead and just start briefing the ILS approach to 20L and making sure all the Captain was doing was flying the airplane. I programmed the FMC; made sure we both had the right frequency; and then landed without incident. The braking action was good. When we got to the gate; the Captain apologized for putting us in that position.I believe ATC put us in a bad position by not giving us a choice or time to make a decision. By turning us and clearing us for an approach we were not prepared for; this put us immediately into the red. Even though he was trying to be helpful by giving us the LOC frequency; there was not enough time to brief and make sure we were prepared to fly the approach in IMC conditions. We failed to recognize the threat and stop the approach right there. With the current weather conditions being an additive; I\'m sure getting on the ground was a priority rather than getting beat up by the turbulence and heavy rain with extended vectors. I was immediately overloaded by changing frequencies; talking to Tower; and trying to configure the aircraft and pull up the right approach plate on my iPad. Then with the distraction of flying through the LOC; the Captain disconnecting the autopilot; and hand flying; I never finished what I was doing.

Data retrieved from NASA's ASRS site 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.