Date: 201809
Local time of day: 1201-1800
Location: HTO.Airport, HI
Flight conditions: VMC
Light: Daylight
Aircraft: Medium Large Transport
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Landing
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: General None Reported / Taken
Contributing factors: Airport
Primary problem: Airport

Narrative: I was pilot monitoring/pilot not flying on the first flight of the day to HTO. The CA (Captain) and I reviewed and discussed the NOTAMs pertaining to [airports] at the gate prior to pushing back in our pre-departure brief. We took off and flew the flight planned route to HTO. About 12 miles out; we were cleared for the visual approach RWY 8. ATIS was calling gusty winds out of the east and I remember making the remark to the CA that I wasn't used to hearing gusty winds on HILO ATIS. There were scattered clouds and some rain showers in the vicinity making the visibility hazy at times during the visual approach. It looked like the runway may have been slightly wet from an earlier passing shower; but hard to tell for sure.The CA gave his landing brief for RWY 8; highlighting our heavy landing weight; shortened runway; no PAPI; ALS and ILS and his intentions to touch down just past the temporary displaced threshold to maximize braking on the shorter runway. As he flew the aircraft on short final/just prior to touchdown; I noticed a slight sinker accompanied by a gust. Just before we touched down; I noticed a few small (approximately 1 ft. long?) red rectangular barriers passing directly beneath us; out to the sides and then one directly in the center of the runway; just before we touched down. The runway surface looked normal/not disturbed/no visible construction with no workers present/nearby. At that time; it was still clear to me that we were intending/tracking to touch down past the closed portion; but it may be close due to the gusty winds and unexpected sinker. We touched down normally; slowed the landing roll and exited the runway. It felt like a normal landing with no indication of running anything over. Once the aircraft was clear of the runway; the CA and I discussed the poorly marked closed portion of the runway and realized that we may have touched down just inside the closed portion after Tower asked us a question about the barriers. They did not provide a number for us to call at that time. We completed the after landing checklists; taxied the aircraft to the gate and shutdown the aircraft. The CA looked up the Tower phone number and told me he was going to call them from outside the aircraft to let them know it was hard to see the markings closing the runway. After I got the clearance back to [departure airport]; Tower radioed our new flight number and asked if we could call them. I relayed the Tower message to the CA and he called them. He inspected the aircraft and noted that there was nothing abnormal / no new marks; etc. Later; as we taxied out; the Tower called us again and remarked that some broken glass was found on the runway. The CA informed that there was no indication of broken glass on our aircraft when he and line service did the walk-around safety inspection. We boarded our passengers and readied the aircraft for the uneventful return flight.




Synopsis: Air carrier First Officer reported that on final descent the barriers for the temporary displaced threshold were difficult to see.