Date: 201405
Local time of day: 0601-1200
Location: LGA.Airport, NY
Flight conditions: IMC
Light: Daylight
Aircraft: B717 (Formerly MD-95)
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class B LGA
Aircraft component: Approach Coupler
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Confusion
Second reporter function: First Officer; Pilot Not Flying
Anomaly: Aircraft Equipment Problem Less Severe; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
Detector: Person Flight Crew; Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Air Traffic Control Issued Advisory / Alert; Flight Crew Overcame Equipment Problem; Flight Crew Returned To Clearance
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: Our aircraft was at 2000 feet MSL; at a speed of 160 knots; and on an assigned heading of 190 degrees to intercept the the LGA Runway 22 localizer outside of GREKO. NY Approach cleared us for the approach. Approach Land was selected on the FCP; and Land Armed was annunciated on the FMA's. Autoflight was engaged. All approach callouts were normal. As the localizer came alive; It appeared that this would be a routine localizer intercept. However; instead of turning right to intercept the localizer; the autopilot rolled the aircraft into a left turn; which would take us through the localizer and result in displacing the aircraft left of course. When the left turn occurred; I immediately disengaged the autopilot; reversed the turn; and turned right as aggressively as was prudent to reintercept the localizer. About this same time; NY approach was directing an immediate right turn; and subsequently assigned us a heading of 240 degrees to re-intercept the localizer.  We reintercepted the localizer; and the subsequent approach and landing were uneventful. Short of disconnecting the autopilot and hand flying the localizer intercept; I do not believe that there is anything that myself; or any other pilot could have done to prevent the autopilot from turning the wrong direction during the localizer intercept. I have seen this event occur in the simulator; but in nearly 35 years of flying and well over 20;000 hours of commercial flying; I had never witnessed this occurrence in flight. Corrective action was swift and correct. I believe there was some type of reverse sensing error that caused the autopilot to turn left. We did not detect any abnormalities with the localizer signal or display.


Second narrative: On approach to RWY 22 PF was given instructions to turn to heading 190 to join the RWY 22 LOC and cleared ILS RWY 22. FP turned to HDG 190. PM called LOC alive and LOC captured. The aircraft made a turn to the left instead of turning to the right. PM called the aircraft turning to the left and the PF made an immediate turn to the right and intercepted RWY 22 LOC. ATC give the crew a heading of 240 to join. No further action taken. Maintain situation awareness at all times.


Synopsis: B717 Captain experiences a turn in the wrong direction by the autopilot when capturing the LOC 22 at LGA. The autopilot is quickly disengaged and a right turn initiated back to the localizer. ATC notes the deviation and issues instructions.