n. — abbreviation, Transportation, especially Northern Canada
a scheduled flight.
Type: 3. Semantic Change — Sked may refer to schedule in general, but in Canada the term is also associated with regular, as opposed to chartered, airline flights and the airlines that provide them. This is a semantic development of sked as an abbreviation of "schedule", which was originally a US innovation (OED-3, s.v. "sked n.")
See also COD-2, s.v. "sked"(2), which is marked "Cdn (North)".