Date: 201908
Local time of day: 1801-2400
Location: ZOA.ARTCC, CA
Flight conditions: VMC
Aircraft: Cessna Citation Undifferentiated or Other Model
Operator: Fractional
Operating under: Part 135
Flight plan: IFR
Mission: Passenger
Flight phase: Climb; Initial Climb
Airspace: Class E ZOA
ATC / advisory: Center ZOA
Reporter organization: Government
Reporter function: Enroute
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Situational Awareness
Anomaly: ATC Issue All Types; Conflict Airborne Conflict
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance
Contributing factors: Aircraft; Airport; Company Policy; Airspace Structure
Primary problem: Aircraft

Narrative: Aircraft X was released off of TRK on the TRUCK4 Departure (a graphical ODP that is very commonly used at TRK). The TRUCK4 has aircraft climb-in-hold (when needed) at TRUCK to 11;500 ft. before proceeding on course. Lately; it has been VERY common for glider aircraft on 1202 codes to 'hang out' around TRUCK and SWR; the major fixes we use for IFR departures due to terrain in the area. At the time; I displayed two gliders (one just north of TRUCK at 11;800 ft. and one northeast at TRUCK within 1;000 ft. of the other glider). AIRCRAFT X was climbing slow enough to require the climb-in-hold procedure at TRUCK. After quoting the glider traffic to the pilot; they expressed concern in their voice and requested a turn. The climb-in-hold would have gotten them dangerously close to the glider; and they were below my MIA (Minimum IFR Altitude) so I could not offer course guidance. I verified their intentions to see if they wanted a VFR climb. Once they requested the VFR climb; I issued a clearance for a VFR climb and issued an altitude above the glider traffic I was displaying. The aircraft turned towards LLC and was not factor with the glider.This almost exact situation is a far-too-common occurrence. While I submitted this as a 'Safety Event;' it certainly falls into the 'Safety Problem' category as well. The terrain; low radar coverage; and increasing volume around TRK makes the airspace very unique and complex. In addition; the high number of Glider activity and VFR traffic in the vicinity creates a serious safety risk. It is not uncommon at all the IFR aircraft departing TRK on the ODP get RA's with Gliders over TRUCK that require evasive action; generally below the MIA. Sometimes we will issue clearances off the ground via or direct SWR to avoid this; but in many cases there are Gliders operating there as well (plus aircraft can still fly the TRUCK4 without ATC clearance since it is an ODP). Because of having virtually no options for slow-climbing IFR departures on the TRUCK4 departure in terms of altitude (the lowest we can ever assign to departures is 12;000 ft.; and depending on route 13;000 ft.) or being able to vector them; this prevents us from being able to safely separate the aircraft from both traffic and terrain. Additionally; the radar coverage around TRK with ADS-B is about 8;500-9;000 ft.; and about 11;000-12;000 ft. for non-ADS-B aircraft; which means there is a strong possibility there is additional glider activity that we do not display on radar. TVL has the same issue; with radar coverage over Lake Tahoe being as bad if not worse; and all the departures (ODP and RICHY6) going over SWR. These aircraft are generally able to gain more altitude than aircraft off of TRK due to SWR being further from TVL than TRUCK is to TRK; but I have seen multiple RAs that require evasive action from TVL departures as well.This risk is also greatly increased when there is a mix of slow and fast VFR aircraft departing and flying in the area as well. Possible mitigations and fixes to this would be to require gliders to remain clear of TRUCK (possibly by creating controlled airspace; increasing the Class D limits; somehow restricting the gliders from being able to operate in that area; etc); as well as create RNAV departure procedures that do NOT have climb-in-hold with at or above crossing restrictions; as well as multiple transitions that we can clear aircraft on with possibility certain routes/legs do not have glider activity along them. Some of us are discussing possibly not releasing IFR departures when there is glider activity due to safety concerns; but this greatly decreases efficiency and will create safety issues with aircraft departing VFR into the glider activity and still having to take evasive action. This is a serious safety concern that must be addressed immediately.




Synopsis: A Center Controller reported a traffic conflict between an IFR departure and a glider and was unable to vector the IFR traffic below the Minimum IFR Altitude.