Date: 201908
Local time of day: 1801-2400
Location: MSO.Airport, MT
Flight conditions: VMC
Weather elements / visibility: Turbulence
Light: Daylight
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Landing
ATC / advisory: Tower MSO
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Human factors: Workload; Time Pressure; Situational Awareness; Fatigue; Communication Breakdown; Confusion; Distraction
Second reporter function: First Officer; Pilot Not Flying
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Landing Without Clearance; Inflight Event / Encounter Unstabilized Approach; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Contributing factors: Weather; Airport; Human Factors
Primary problem: Human Factors

Narrative: During a very long day; (12.5 hours of duty; almost 8 hours of scheduled block; and at least 6 separate calls to maintenance through the day); we had an extremely busy approach in less than ideal weather; visual; but moderate turbulence and winds gusting at 28+ knots; CA (Captain) took the controls to salvage and stabilize an approach to Runway 30 at about a 4 mile left base. While this exchange was going on and we were getting tossed around; we were given our handoff to Tower but failed to make the switch. In the flare at about 40 ft.; we hear over radio 'Aircraft X call Tower'. The First Officer immediately switched frequency and made a call; but it was incidentally the wrong frequency and we landed. We immediately called Tower as we pulled off the runway and were given a subsequent taxi clearance.Task Saturation; extreme winds/weather; original Pilot Flying misjudged distance to runway. We briefed the approach on the ground and rebriefed it again in flight and CA stressed multiple times the severity of the approach into MSO; FO (First officer) fell behind the aircraft leading to the control swap at critical stage of the approach. Rote response due to saturation for '500 to go' call out.Stricter attention to position of light switches and to SOP (Standard Operating Procedure) required callouts for landing. Maybe make MSO a captain only airport; even the visuals in there are difficult sometimes.


Second narrative: I was flying an RNAV (Area Navigation) approach into Missoula. The Captain was visual with the airport and programmed in a left 90 degree base turn onto final 4.6 nm from the runway. I did not see the runway; and was high. The Captain; who could see the runway; took the controls to avoid a go-around in the narrow valley; shortly after being directed to contact Tower. I now became the Pilot Monitoring and missed that he hadn't called Tower yet; and we therefore did not have a clearance to land.The RNAV D approach into Missoula requires a very steep descent within 10 miles of the airfield. We were experiencing moderate turbulence on the approach. We were very task saturated with trying to slow down in a steep descent and get configured when the handoff to Tower was given; and subsequently the needed communication between us about the need to contact Tower was missed.This is a very difficult approach for a new FO (First Officer) the first time here. I should have noted that a steep descent was necessary unusually close to the airport while needing to get aligned with the runway; and slowed down and configured further out. This would have prevented the need for the Captain to take controls right after being handed off to Tower; and he therefore would have made the call to the Tower to get clearance to land.


Synopsis: Flight crew reported landing without clearance.