Date: 201708
Local time of day: 1201-1800
Location: EUG.TRACON, OR
Light: Daylight
Aircraft: Medium Transport; Low Wing; 2 Turbojet Eng
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class E EUG
ATC / advisory: TRACON EUG
Second aircraft: Widebody Transport
Reporter organization: Government
Reporter function: Approach; Instructor
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Distraction; Human-Machine Interface; Situational Awareness; Confusion; Workload
Anomaly: ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Air Traffic Control Separated Traffic; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Took Evasive Action
Contributing factors: Human Factors; Aircraft; Airspace Structure; Environment - Non Weather Related; Procedure
Primary problem: Procedure

Narrative: I was training on the MFR arrival/departure position when Aircraft X came to us from the south. MFR was landing RWY 32 so the pilot was already in position for a straight in visual approach. We descended him to 10000 in preparation. MFR airport has high MVAs surrounding it so 8700 is the lowest we can go from the south; southwest is 9100; and southeast is 7800. When Aircraft X reported the field in sight we cleared him for the visual approach and he began his descent. He was the only aircraft we were talking to.As I was discussing some of the unique scenarios in MFR with my trainee I noticed a target about 9 miles SE that appeared to be straight in for RWY 32 and was tagged up by MFR tower. It was Aircraft Y [a heavy widebodied aircraft]; I took a minute to look at position and speeds; Aircraft X was still doing 250 kts now inside of 15 miles; Aircraft Y was only doing about 160 kts. I pointed out the traffic to Aircraft X and he got Aircraft Y in sight and asked me to verify Aircraft Y was number 1. Given position I decided it would be best for Aircraft Y to be number one and started to cancel Aircraft X's approach clearance but then realized he had just crossed below our MVA. I asked the pilot if he could maneuver out east to follow Aircraft Y on the visual and he confirmed.MFR tower also has taxiway construction going on which blocks the end exit for RWY 32 which meant Aircraft Y would have to stop and back taxi on the RWY. I informed Aircraft X of this and told him to maneuver as necessary and sent him to the tower so they could work with both pilots. In the end Aircraft X ended up having to make very drastic maneuvers on his visual approach in order to get in behind Aircraft Y. At the same time there was no way I could have gotten Aircraft X in front of Aircraft Y. With multiple TFRs in the MFR area this time of year; these [widebody] aircraft become a huge problem. MFR tower is constantly overworked trying to handle all the inbound and outbound [aircraft] and adding a back taxi scenario in the middle creates a huge safety risk. Additionally none of the aircraft call approach for sequencing into the airport. Which leaves us at the approach control guessing as to what the sequence really is. MFR tower has requested 12+ miles in trail for the back taxi operation but we can't provide that when an aircraft is coming straight in on a steep approach because of terrain and they put a slow moving [heavy aircraft] right in the way.My first recommendation would be that construction projects such as this should not occur in the middle of summer season. It happens every year end of July/August time frame. This is nothing new; so the project should have been done in June or not until after. Second; the aircraft; at least the larger ones; should be calling approach on the inbound for sequencing. Had Aircraft Y called us inbound even 15 miles out we could have easily vectored Aircraft X and started reducing his speed earlier creating a much safer scenario. If MFR tower is going to need additional spacing; and is going to sequence aircraft in front of our arrivals they should be looking at a further range on their RTD (RADAR Display) and calling us to coordinate in that scenario. Currently MFR tower is only required to look at 15 miles I believe which in this scenario was too little to allow timely coordination.




Synopsis: EUG TRACON Controller reported an unsafe situation when a heavy aircraft approached MFR without contact with Approach and they had to sequence a commercial jet in behind the heavy.