Prior to takeoff the aircraft was cleared to track via a Standard Instrument Departure procedure referred to as (Runway) 21 Clackline 1. After takeoff the aircraft was observed to make an early left turn. The Tower controller kept the aircraft in sight to ensure that there was no confliction with another aircraft which was in the vicinity. It was determined that the crew of GIA 879 had flown a 21 Clackline 2 departure procedure. This procedure was on the adjacent page of the relevant document to the 21 Clackline 1 procedure.
