Date: 201902
Local time of day: 1201-1800
Location: HXD.Airport, SC
Weather elements / visibility: 10
Aircraft: Medium Transport; Low Wing; 2 Turbojet Eng
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Initial Approach
Airspace: Class D HXD
ATC / advisory: Center ZJX
Aircraft component: GPS & Other Satellite Navigation
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Human factors: Time Pressure
Second reporter function: First Officer; Pilot Not Flying
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Other / Unknown
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance
Contributing factors: Human Factors; Procedure
Primary problem: Ambiguous

Narrative: Upon departure; weather reported at HXD was winds out of the north; OVC 011 with visibility of 10SM. Captain was Pilot Flying and First Officer was Pilot Monitoring. Takeoff; climb; and cruise were normal. We set up for the RNAV (GPS) to RWY 3; winds out of the north. Approach Control gave us a descent down to 4;000 ft. and shortly thereafter; approaching 10;000 ft. on our descent; they told us 'GPS signal unreliable in the area; set up for VOR-A'. High workload environment; now below 10;000 ft.; the First Officer (Pilot Monitoring) set up the approach and briefed it for me as well. The Jeppesen approach plate for the VOR-A has an MDA of 800 ft. which we briefed and flew into our otherwise normal Flaps Full landing; instead of our SOP prescribed 1;000 ft. MDA for circle-to-land approaches; which the VOR-A approach is. Also would like to note there were no NOTAMs of GPS signal unreliability. There were several casual factors. It was my first time flying into HXD. Quick flight; set up the approach we thought we were to shoot into the airport; then had a quick change of the approach in a high workload environment. It is an approach we don't normally shoot; combined with a short runway I have never been to before. The First Officer had been once before. We saw the published MDA shot the circle to land approach at the published MDA; in visual conditions. We debriefed after the flight and both realized our SOP minimums for a circle to land are higher. High workload was the main cause I would say. [I suggest] not many approaches to be flown into HXD. I would suggest a note [in our manual]; published MDA may be lower than company MDA. Also; it is always ok to ask for delay vectors to make sure we are executing our duties safely and correctly.


Second narrative: Operating flight HXD. On the preflight; we checked the NOTAMs and weather and determined all was legal to continue with the flight. In cruise; I; as Pilot Monitoring; picked up the ATIS in HXD which reported 800 ft. ceiling and Runway 3 in use. We set up and briefed for the RNAV (GPS) RWY 3 into HXD which had a straight in [decision altitude] of 334MSL. Passing through 10;000 ft.; the Approach Controller informed us that GPS signal in the area was unreliable and would not be able to do the RNAV 3 approach and would be doing the VOR-A; which is not aligned with the runway and would hence be a circle to land. With little time to prepare everything; I loaded and briefed the approach for the Captain who was focusing on flight duties. VOR-A approach has an MDA of 781 ft. and 1SM. The weather was 10SM and 800 ft. ceiling and was deemed legal to do the approach which we successfully did. There was no mention of RNAV unreliability in our NOTAMs or on the ATIS. On the debrief; we realized that we infringed on the company's restriction of needing to have at least a 1;000 ft. ceiling to conduct a circle to land approach. This slipped our minds due to the high workload into a small airport; doing an approach type which we rarely use. Due to the limited approaches into HXD; maybe a reminder of the circling limitation would be helpful to future crews [in our manual]. We would also do our best in the future to ensure all limitations and restrictions are observed by slowing down and giving ourselves as much time as possible to think and plan things through.


Synopsis: Air carrier flight crew reported a late change from the RNAV (GPS) Rwy 3 approach to Hilton Head to the VOR-A circling approach; with an MDA very close to the reported ceiling; due to a reported loss of GPS signal.