B767-300 and 300 ER
Flight Crew Air Transport Pilot (ATP)
Workload; Troubleshooting; Time Pressure; Distraction
Aircraft Equipment Problem Critical
Air Traffic Control Provided Assistance; Air Traffic Control Issued New Clearance; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Landed As Precaution; Flight Crew Diverted
Environment - Non Weather Related; Aircraft
About 2 hours 48 minutes into our flight half way between MUNEY and JEBBY intersections; on M-202; at FL370 M.80; the captain's front windshield began arcing internally; from lower right to upper left. An arc line was created with fast moving; flickering internal sparks. The line ended up being almost 20 inches long. Just as the arcing stopped; a loud bang occurred and nearly the entire windshield became badly cracked. All of this happened in about 6 seconds. We turned off the window heat as quickly as possible. We [contacted ATC]; checked the TCAS display for potential traffic and decided to descend to 10;000 feet; slowing from M.80 to 250 knots. Chose Halifax; as the nearest-suitable-airport; which was about 200 miles or less; away.  We completed the QRH instructions for cracked windshield and emergency landing.As we approached Halifax we requested ARFF (Air Rescue Fire Fighter) to meet the aircraft. Weather was VFR at the airport. We landed just under max landing weight with a vertical speed of approximately 200 ft/min. Rollout was uneventful using predominantly reverse thrust. ARFF reported no apparent damage to undercarriage nor any signs of brake heating. We taxied to the gate.
A 767 crew reported sustaining an arcing; then cracking; windshield while at cruise altitude. They initiated an expedited descent and successfully diverted to a suitable enroute alternate airport.