Date: 201706
Local time of day: 1201-1800
Location: ZSE.ARTCC, WA
Flight conditions: Marginal
Weather elements / visibility: Icing; Turbulence; Thunderstorm
Aircraft: Commercial Fixed Wing
Flight plan: IFR
Flight phase: Cruise
Airspace: Class A ZSE
ATC / advisory: Center ZSE
Second aircraft: Commercial Fixed Wing
Reporter organization: Government
Reporter function: Enroute; Handoff / Assist
Reporter qualification: Air Traffic Control Fully Certified
Second reporter function: Instructor; Enroute
Anomaly: ATC Issue All Types; Airspace Violation All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Air Traffic Control Provided Assistance
Contributing factors: ATC Equipment / Nav Facility / Buildings; Weather; Staffing; Procedure; Human Factors; Environment - Non Weather Related; Airspace Structure; Chart Or Publication
Primary problem: ATC Equipment / Nav Facility / Buildings

Narrative: I took the sector while training was occurring on the Radar position. I was briefed that this plane was going to conflict with someone descending into Spokane and that the alerts for the entire flight plans involved were muted so we could see if the trainee would catch it. I assumed that the issue was the red alert potential of a landing aircraft. When the Radar Trainee caught this I assumed that the tasks related to the aircraft were fulfilled according to my briefing; seeing no color any longer on the En-route Decision Support Tool (EDST).Shortly after taking sector; we became very busy; up to the point of a red sector. We had two deviations and I was offline for TMU(Trafic Management Unit) coordination; two Tower releases; and several transmissions with TRACON. The business got out of hand with the weather and the radar controller was way behind the flick. I attempted to work with TRACON to help out and to scan for anyone that might be going to the weather; since it was getting worse. All the while the orange alert was still muted.As we got busier; we went to VTABS (Backup landline system) with literally one minute of warning. As we switched over and increased the workload; we realized the volumes were all too low to hear us being called on the shoutlines. As this was being fixed; an aircraft entered the firing center of a Restricted Area. We went back to attending to the weather and climbers/descenders and the Radar Controller trainee got back on track. I gave a briefing in the middle and realized at the end the aircraft was in the Restricted Area as I spoke of traffic.I recommend that we at least have a tracker on all red sectors; especially when weather deviations are involved. I almost called for a split; but we were far too deep into it by then for it to be effective. Split red sectors before they happen and add tracker when stuff really hits the fan. Also; we should NEVER; EVER mute alerts on an airplane regardless of the training benefit. Having taken the mutes I was less likely to remember an issue and it was an incomplete transition of situational awareness.


Second narrative: On the job training (OJT) was being conducted on the sector all combined. Prior to the event; VTABs (Backup landline system) was activated eliminating the Radar controller's ability to make landline calls. The sector team had one minute notice of the switch to VTABs. Aircraft X departed with routing through a Restricted Area which was active to 29000 feet. After the fact I found out the Radar Assist muted the airspace warning on the display. As Aircraft X approached the Restricted Area boundary my attention was directed to the area where my trainee was working Aircraft Y with the Boardman Complex in use to 15000 feet. The aircraft was climbing out and into an EXTREME precipitation area. Aircraft Y asked for a turn north of weather but into Active Military Airspace. The trainee choose to leave the aircraft on route south of the Active Military Airspace until they had climbed above it; but toward the weather event. I was concerned that this plan would not work as the aircraft was climbing slow and there was traffic on vectors to miss Aircraft Y. My concern was that we were limited on options and I was trying to come up with a safe solution. Meanwhile; another aircraft was deviating and needed a point out to an adjacent sector. I was coordinating with Radar Assist which had only been on position a short time. We had at this point lost our ability to use the landline as we were in VTABs so it was hectic. Additionally; being in VTABs and having limited proficiency I was helping the sector team to make a call. Although busy I continued to scan the sector but missed the conflict with Aircraft X and the Restricted Area repeatedly.While ultimately; the responsibility for the separation is completely mine. There were many contributing factors. While not one was the lynch pin factor; there was a greater quantity at play than normal. Muting the Alert in EDST prior to taking action; I was told the first Assist muted the airspace alert to allow the trainee to 'catch' it. I understand this line of thinking but find it to be Ill advised and if this action was to be taken the Instructor should be made aware of it first.The complex weather/airspace situation described in the narrative section of this report definitely pulled my attention from the rest of the airspace and caused me to overlook the event. It is hard to make recommendations on this other than more strategic splitting of the sectors and more awareness on my part. Having the VTABs operation while busy with weather deviations was one too many things and we should make a more detailed analysis of the traffic and factors at play when enabling this mode as it cripples the Radar controller's ability to affect coordination.


Synopsis: Center Radar controllers reported an aircraft was allowed to fly through a hot Restricted Area that the Assist controller had muted the warning system.