B737-700 Flight Crew reported moderate turbulence during the final approach resulting in a go around in which ATC assigned an unsuitable heading due to weather and terrain restrictions. Captain invoked Captain's authority to maintain heading and altitude clearance and also requested clearance to the alternate airport.
Synopsis
B737-700 Flight Crew reported moderate turbulence during the final approach resulting in a go around in which ATC assigned an unsuitable heading due to weather and terrain restrictions. Captain invoked Captain's authority to maintain heading and altitude clearance and also requested clearance to the alternate airport.
Narrative
We were descending into ZZZ on a flight from ZZZ1. We knew there would be moderate turbulence in the area and experienced at least occasional moderate on our descent below 16;000 ft. There were clouds in the area that indicated moderate turbulence and passed through a portion of them on our descent at about 16;000 ft. This turbulence was greater-than-moderate. Maybe not quite severe; but as you'll see we did not want to go back through them again. We were given a visual approach to Runway XXL and experienced moderate turbulence on the approach.In the flare the main wheels barely touched down; and we got a gust that picked us back up. After realizing the landing could not be made safely; we accomplished a normal go-around. On the go around we were given a climb to 11;000 ft. and a heading of 170. We complied with these instructions. Then as we were still cleaning up the airplane; ATC gave us a left turn to a heading of 070. Turbulence at the time was moderate and just bordering on; but not quite; severe. We told ATC that we wanted to maintain our heading and climb as the vector would have put us directly in the nearly severe turbulence in the clouds we flew through descending into ZZZ. The conditions were VMC on the west side of those clouds and we monitored clearance from the terrain.ATC gave us another easterly heading which; again; would have taken us through possibly severe turbulence; and we asked to maintain heading and climb above the turbulence so we could evaluate fuel and whether another approach could be made. Maintaining terrain clearance and using Captain's emergency authority; I elected to maintain heading and we told ATC we could not comply with the turn and requested a climb. ATC gave further instructions which we complied with that didn't require a heading into the turbulence; but no further climb was given.I assessed our fuel and made a decision at that time to divert to our alternate of ZZZ2. We requested the diversion. We were given a heading and altitude toward ZZZ2 and proceeded and landed.En route we were given a number to call for a 'possible deviation.' We acknowledged the number and landed without incident at ZZZ2.I probably should have declared an emergency for fuel. In hindsight ATC was probably vectoring us back for another approach. We were still evaluating whether that was possible. But ATC; I think; misunderstood our request to stay out of potentially severe turbulence. Better communication between us and ATC might have helped the situation. ATC's intent to keep us in their airspace while try to vector us back and our intent to avoid severe turbulence (while maintaining terrain clearance) and evaluate whether a return was possible conflicted.
Second reporter narrative
ZZZ1 to ZZZ for visual; Runway XXL. For context: 1) I'm on Day 2 out of IOE. I know where information is available to me in the flight deck; but my scan is not innate; yet. As much as I'd like to have better numbers for what the winds were doing at each spot and exactly what our assigned headings and altitudes were; I'm just not there; yet. I'm very much using conscious brainpower to gather and process info. 2) On our way into ZZZ; we were vectored north along the eastern edge of a mountain ridge southeast of the city and clipped the easternmost edge of the clouds over those peaks. There was immediate moderate turbulence (closer to severe than light) just clipping the edge of those clouds. I'll call them the 'turbulent clouds.' At the time; they looked like a collection of several merged cumulous clouds. We were warned of gains/losses of airspeed 10-15 kts. by PIREPS in front of us and the crosswinds were pretty strong from west-to-east. Just about at touchdown; we got a gust of wind and the Captain executed a 'go-around.' We climbed out in VMC; on runway heading; roughly following the southbound valley that the interstate follows. We had unlimited visibility along our path to the south and clear awareness of the terrain on both sides. Departure gave us a level off at 11;000 ft.; which ended up being right in moderate (nearly severe) turbulence as we were level with the mountain peaks to our west (only a couple miles away); and downwind of the west-to-east winds. I asked for an immediate climb to get out of the turbulence; and the controller issued it with a turn to the east; directly towards the turbulent clouds over the city.I informed the Controller we were unable the turn to the east because of the weather; at which point he stated we were below MVA and needed to turn in order for him to climb us. After a couple of radio exchanges; it was clear we only had to climb 100 ft. on an easterly heading before we could request a turn to the south again; so we attempted that. Ultimately; we ended up on a 170 heading and climbed above the turbulence (though I tried to get further to the right/west because we were brushing right up against the turbulent clouds). Somewhere in the exchanges; Departure did ask for our intentions; and I let them know we wanted to continue south for about 10 more miles. At the time; that was to get around the turbulent clouds and give us time to analyze/discuss our next decisions (try again or divert). Ultimately; the Captain decided we needed to divert because of our fuel state; and that process went smoothly. This was a very compressed timeline with highs winds; terrain; and turbulence; and a challenging mental model to share with the Controller who couldn't see or experience what we could. I was confident then; and now; that the safest actions we needed take at that time were to continue climbing out of the turbulence in the direction where we had great visibility and terrain clearance; while NOT turning directly into the heart of the clouds to our east that we already knew had strong; moderate turbulence on its fringes. Of note; on our return flight from ZZZ2 to ZZZ about two hours later; the clouds over the city appeared as a collection of several standing lenticular clouds; interconnected along the spine of the mountains underneath them.The only options I can think of that would have allowed us to continue with our own terrain clearance and climb in VMC would have been to declare an emergency or cancel IFR for two minutes then pick it back up. I don't know of an in-between way to concisely communicate to ATC that we were in a great spot to take responsibility for terrain clearance while on a south ground track that would avoid the turbulent clouds. I think the Controller was trying to vector us back for another approach and/or shortest direction back into an area where we would be above the MVA. If there's a way to relieve the Controller of his/her terrain clearance responsibility without saying 'emergency' or 'cancel;' I don't know what it is. It would have been nice to be able to say something like; 'We got terrain clearance; continuing 180; climbing to ___ (assigned); let us know when you can turn us west to go to ZZZ2.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.