Flight Crew Air Transport Pilot (ATP)
Confusion; Human-Machine Interface
Aircraft Equipment Problem Less Severe; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Issued New Clearance; Air Traffic Control Issued Advisory / Alert; Aircraft Equipment Problem Dissipated; Flight Crew Executed Go Around / Missed Approach
Aircraft; Human Factors
While on the ONYON One Arrival we were cleared the arrival routing for the ILS Precision Runway Monitor (PRM) Runway (RWY) 8L.  Prior to the downwind leg; the approach controller provided the current RVR of >6000.  When on the radar downwind the weather was updated to 2600 RVR.  I was flying and the Captain briefed the changes in procedure required for a Monitored Approach.  About the time the controller turned us to a 180 heading for the base leg the master caution flashed and the EICAS message 'AP TRIM IS LWD' flashed for about a second and both lights extinguished.  The autopilot continued to function fine.  We were given a 120 heading and cleared for the ILS PRM RWY 8L.  While on the ILS final; the aircraft 2 ahead on the approach landed and provided a PIREP that they had the runway lights in sight at 450 feet AGL.  Our approach was uneventful and stable until 500 feet AGL.  At approximately 500 feet AGL; the Pilot Not Flying (PNF) glanced outside searching for the approach/runway lighting.  I noted the command bars direct a right turn and an amber boxed 'A' flash on the PFD for about 1 second.  I cross checked that the aircraft was on course and on glide path as the aircraft entered a right bank turn.  I was initiating a go-around simultaneously as the PNF looked back inside and directed a go-around.  The aircraft had reached approximately 10 degrees right bank as I pushed the Take Off Go Around (TOGA) button; pushed the power up; leveled the wings and raised the nose to 7-10 degrees nose up.  I simultaneously directed 'set go-around power; spoilers in and flaps 8.' The PNF set the power; reset the flaps to 8 and notified the tower of our missed approach.  Tower then stated; 'you are headed toward runway 8R.' I then began the missed approach turn to the north noting the altimeter read 1700 feet.  Tower handed us off to Atlanta Approach.  We were given a heading of 270 and altitude of 5000 feet to put us back in sequence for the ILS PRM RWY 8L. The controller provided updated weather of touchdown RVR 1800; mid-point RVR 1600 and roll-out RVR 1800. We flew an uneventful monitored ILS with the Captain going 'visual' at 200 feet AGL.Changing weather due to the fog setting in right at sunset provided the greatest environmental threat.  We had briefed and were prepared for monitored approach procedures to aid in mitigating this threat.  The autopilot/flight director error during a high workload phase of flight compounded the low visibility threat.  The aircraft autopilot/flight director error caused the aircraft to turn off course and result in a course deviation and an undesired aircraft state on short final in the weather.  The undesired state was realized and an immediate missed approach/go-around was executed.Go-arounds are in frequent and missed approaches are even more infrequent.  This is the first actual missed approach in the aircraft I had flown.  Out of about 210 flights I had only gone around once.  The training department is very adamant about planning approaches to go missed.  That way you are best prepared for the missed approach procedure.  The challenge is maintaining that mindset.  Even tougher when aircraft in front of you are providing PIREP's and landing from the approach.  I was vigilant during the approach but I do admit the autopilot directing a turn away from course was surprising.  Although it probably took a second to recognize and react; the undesired aircraft state (course deviation) happened quickly. The tower advisory interrupted the flow of the go-around procedure and we did not retract the gear until initiating the turn to the north.  Also; in accordance with the published missed approach; I should have turned toward the north at 1500 feet.  A lot happens quickly during a missed approach and I now know it probably won't go as cleanly as in training. If external factors are causing the missed to not go cleanly; I will just stay on the profile.  Even more so now; I fully appreciate the mindset of planning every approach to a missed approach. One item the training shop may want to introduce is a missed approach due to a minor aircraft/navigation/flight director system malfunction.  As I recall most every missed approach in training was due to weather below minimums.
We had an issue with this airplane with the Jet pipe overheat fail message in flight even though we thought it had cleared. We notified maintenance on it and went on to Atlanta. When we arrived we were told to expect Runway 8L and fly the Runway 8L Transition. Somewhere between the descent below 7000 feet and turning to base on a vector we briefly saw a Autotrim message; I didn't quite see what message we got but it cleared since I didn't know what the message was. We continued along and started the approach we had briefed; a Category I since the RVR initially was reported at over 6000. After we were cleared for the approach and switched to tower the RVR had dropped to 4000. Still ok for the approach. Everything seemed to go smoothly. Once inside the final fix the RVR was reported to be 2600 RVR and the guy in front of us reported the runway at 450 feet AGL. When we got to around 500 AGL the airplane appeared to start drifting a little bit right of course; then in a matter of seconds the airplane turned to the right and the course turned amber and we were moving away from the course. The Autopilot trim warning came on and we were clearly not tracking the course any more. I immediately called for the go around. We initiated the go around/missed approach. Initially we had the wings level and didn't turn right away due to proximity to the ground. However the heading was about 15 degrees to the right of where we were when on the course. So our initial climb was towards Runway 8R. I realized this and immediately let Tower know we were going missed due to automation failure and she directed us to turn to a heading of north immediately because we were flying almost over Runway 8R. We got the airplane cleaned up (all be it a little bit late trying to make sure we had a course and altitude). The Autopilot came off when First Officer (FO) hit the Take Off Go Around (TOGA) Button. The airplane seemed out of trim for a bit in initial climb but since I was not on the controls I am not sure about that. Threats. Weather deteriorating and sense of security that the airplane in front of us saw the runway at 450 AGL. Trusting automated system so much when it started doing things it isn't supposed to do we got caught somewhat flatfooted and had to do a missed approach where and when we didn't expect it. The autopilot had turned the airplane to the right by about 15 degrees by the time we started climbing. The initial reaction was to climb straight when we really needed an immediate turn to the north or at least back to the course. The undesired state was that we were right of course and flying in the wrong direction due to this failure. Not doing missed approaches a lot makes us slow in execution of the procedure. Due to the unusual occurrence and new checklist we were out of normal rhythm. The First Officer and I discussed the checklist after we landed and we both believe we did ok but we did use some of the old terminology during the procedures. We briefly briefed another ILS (Category II this time) and we did the approach again; this time on our toes for the failure and ready to go missed immediately if the course even would have deflected a little bit. (The threat being that we see the course on the ILS deflect some time and the autopilot getting back to the course) I think this would be a good training event. Have the automation send you off course at 500 AGL on an ILS when you don't expect anything like that to happen. Another thing might be to verbalize the missed approach one more time just before you start the approach. We thoroughly briefed the approach; yet when we went around we were still trying to analyze what happened with the autopilot instead of being totally on the ball for this missed approach which is now the most important thing to do for the day.
A CRJ200 Flight Crew experiences an autopilot malfunction at 500 feet AGL during a low visibility approach to Runway 8L at ATL. A missed approach is initiated but not before the aircraft has turned 15 degrees toward 8R. When the Take Off Go Around (TOGA) button is pushed the autopilot disconnects causing a late turn away from Runway 8R and late gear retraction. The second approach is a Category (CAT) III and successful.