Boeing 757-200 – Oil Pressure Loss

N692DL, a Boeing 757-200 aircraft operated by Delta Airlines, was conducting flight DAL1601 from Minneapolis-St. Paul Intl/Wold-Chamberlain, MN (KMSP) to Anchorage/Ted Stevens Intl, AK(PANC) with 6 crew members and 180 passengers on board. While in cruise flight at FL360
approximately 25 nautical miles East of Fort St. John, BC (CYXJ), the flight crew noticed the LH
Engine (Pratt & Whitney – USA PW2037) oil quantity indication decease to zero. The indication
was accompanied by a LH engine low oil pressure EICAS message. The oil pressure indication
had decreased to 70 PSI. The flight crew referenced the QRH and reduced the LH engine to idle.
No vibrations were noted. The flight crew then declared an emergency and requested a diversion
to Edmonton Intl, AB (CYEG) where the aircraft landed without further incident with ARFF in
attendance. A preliminary inspection of the aircraft found fluid on the left engine cowl. A subsequent inspection by maintenance personnel found a leak in an oil pressure line between the main gearbox and the angle gearbox.