On 23 September 2012 at 1855 Eastern Standard Time, a Metro 3 aircraft registered VH-SEF (SEF) and operated by Brindabella Airlines, departed Narrabri on a scheduled passenger flight to Sydney, New South Wales. On board were seven passengers and two flight crew.

Passing through 10,000 ft, the Captain asked the First Officer (FO) for the transition checks which included a check of the cabin altitude by the FO. The transition checks were completed with no abnormalities found. During the climb, the Captain began to feel progressively worse and asked the FO to recheck the cabin altitude.  Before the FO could respond, the cabin altitude warning light illuminated at a cabin altitude of 17,000 ft. An emergency descent to 10,000 ft was performed.

As a result of this occurrence, the operator amended their standard operating procedures in regard to; the transition checks, maintenance schedule for the cabin altitude warning system and the re‑currency simulator training syllabus.

Flight crew are reminded of the dangers of hypoxia and the need to put oxygen masks on without delay if hypoxia is suspected.

Aviation Short Investigation Bulletin – Issue 14