A coroner has found the death of a teenager in a police shooting in Sydney's south-west was avoidable.

Ali Antoni El Hafiane was shot dead by a policeman after carrying out an armed robbery at the High Flyer Inn at Condell Park in 2010.

The 19-year-old was unarmed, but his accomplice had a machete.

They were being chased by an officer towards two undercover police who opened fire.

Deputy State Coroner Hugh Dillon has found the death could have been avoided had there been better planning and had standard procedures been followed.

He said the officers acted bravely, but their training failed them and they did not implement a policy of containment and negotiation.

The coroner said it was a great tragedy that the teenager had not lived to learn from his mistakes.