Martinair Flight 138 was a chartered flight from Surabaya, East Java, Indonesia, to Colombo, Sri Lanka. The aircraft was operated by the Dutch airline Martinair on behalf of Garuda Indonesian Airways. On 4 December 1974, the aircraft, a McDonnell Douglas DC-8-55CF, crashed into a mountain shortly before landing, killing all 191 people aboard – 182 Indonesian hajj pilgrims bound for Mecca, and nine crew members. The crash remains the deadliest in Sri Lankan aviation history and the third-deadliest involving a DC-8, after Arrow Air Flight 1285R and Nigeria Airways Flight 2120. At the time of the crash, it was the second-deadliest aviation accident in history, after the crash of Turkish Airlines Flight 981 which occurred earlier that same year.

Martinair is a Dutch cargo and passenger airline headquartered and based at Amsterdam Airport Schiphol and a subsidiary of Air France–KLM. The airline was founded in 1958 by Martin Schröder. Since 2011, Martinair has operated entirely as a cargo airline with scheduled services to 20 destinations worldwide and additional charter flights. Prior to that date, passenger flights were also operated.