B767 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Situational Awareness
Conflict Airborne Conflict; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Executed Go Around / Missed Approach; Flight Crew Diverted
Human Factors; Weather
There were thunderstorms in the Taipei area. We saw a break in the weather and started the approach. Initially there was no turbulence at 4700 feet outside FRANK. Passing FRANK; we descended with Flaps 15 at approximately 170 kts. We forgot to set the missed approach altitude of 3000 ft due to concern over the weather. At approximately 3500 ft we hit severe turbulence. There were three simultaneous go around calls. I am not sure who called it first. We began to climb. RCTP Approach Control had to vector traffic away from us due to our climb. There were no TCAS RA or TA alerts. We then diverted and landed uneventfully.I have mixed feelings about whether setting the missed approach Altitude to 3000 ft would have changed the decision to climb. The severe turbulence could have become a severe windshear situation.
Upon arrival in the terminal area in RCTP; the weather was much worse than forecast. There was a large area of weather of varying intensity North and East of the field moving NE. The winds at RCTP were fairly strong out of the south; so only 23L or 23R was an option for landing. In the terminal area; we initially received vectors and deviated around some weather areas. As relief pilot on this leg; I made a quick call to Dispatch by satcom at the Captain's request. We wanted to explain the weather situation and confirm the best alternate if RCTP was unusable. During this time we also entered a brief hold in a clear area at ATC's request; probably for spacing and sequencing. We all agreed on a minimum fuel number (25.0) that could be reached before diversion was necessary. Having a good number in hand was very helpful in future decision making.The weather on the extended final looked reasonable if not great; with large areas of green; some smaller areas of yellow on or near final; and a few small areas of red in the general vicinity but not on the extended final. Other aircraft were trying the approach with varying success. After discussion; we felt that an approach was worth trying even though a missed approach and diversion was a real possibility. We requested and received vectors and then approach clearance from ATC. I believe that it was cleared direct FRANK; cross at or above 4700; cleared the ILS 23R approach. The FO was flying at this point with the Autopilot engaged as usual. We flew through some moderate to heavy rain; but the ride was almost completely smooth. We captured the LOC and GS and started down. We could see that the precipitation ended in about 5 more miles; and the last 5 miles of final and the airport were in the clear. Things looked good at this point. About in the vicinity of EMILY and (12.5 DME) and maybe 3;500 ft the turbulence became very bad approaching severe. I could also see the magenta radar turbulence display pop up. We were all in agreement to abandon the approach and the FO called missed approach and pushed the Go Around toggle. The power came up and the aircraft started a climb. 4;700 was still set in the MCP window as we had not yet reset it to the missed approach altitude of 3;000. The Captain reported the missed approach to ATC; and the controller immediately said that he needed us at 3;000 as he would have traffic crossing final at 5;000 I believe. I picked up the traffic (TA about plus 500 and I'm guessing 5 miles) on the MFD screen and clearly told the FO he needed to descend NOW as there would be a conflict. The traffic had become a bigger threat to me at this point than the weather. The FO disconnected the AP and did a nice job promptly descending to 3;000 in very challenging flying conditions. The traffic quickly changed to white as we increased vertical separation. We never did receive a RA. Once clear of traffic; ATC gave us a climb and we promptly diverted as we had reached minimum diversion fuel.This was a strange one. It is extremely uncommon to execute a missed approach when you haven't even descended to your missed approach altitude. Reducing thrust and descending during a severe turbulence and a quite probable windshear encounter seems counter intuitive. My thought previously would have been to get the airplane powered up and climbing; and then get an amended clearance from ATC as soon as possible. However the unexpected traffic crossing final at the worst possible time and place for us made that impossible. In the future; I am thinking that I will reset the MCP altitude to missed approach altitude ASAP. I had been in the habit of doing it at or just inside the final approach fix and then checking it at the 1;000 foot call. That works; but not if you have an early missed approach like we did. I will think through various early missed approach procedures. We rarely see and hardly ever practice a scenario like this; where we are cleared for the approach and descending but have not reached the MAP altitude at the time of the miss. It's essentially a descending missed approach procedure. Add some severe weather and traffic and it gets stranger.
B767 flight crew reported a missed approach and diversion from RCTP due to severe turbulence. The missed approach began above the published missed approach altitude and the climb caused a conflict with an aircraft.