A structural engineer has admitted an oversight on his part contributed to a woman's death in the devastating February earthquake.
The evidence was presented to the Canterbury Earthquakes Royal Commission on Monday.
Linda Arnold was sitting in her parked car talking on her cellphone and was crushed when a six-tonne panel fell from the Ballantynes department from a height of three storeys on 22 February 2011.
Unlike panels on the east side of the building, the panels on the south side where Ms Arnold's car was parked were missing the brackets needed to tie them to the building.
Dick Cusiel, the structural engineer who oversaw the design of the building, admitted that the original plans did not include instructions for the panels to be properly fixed to it.
A tearful Mr Cusiel said his oversight was an obvious one, but was also missed by the Christchurch City Council engineer who approved the plans.
"The matter has weighed very heavily on me and will always. I extend my very sincere condolences to the family of the victims for this extreme, tragic event," he said.
The commission was told this case was unlike any of the others heard so far, because the building was relatively modern and did not suffer any structural damage.
Council engineers failed to pick up design fault
Christchurch City Council has admitted it failed to provide a second line of defence during checks on the building.
Environmental policy and approvals manager Stephen McCarthy told the Commission its engineers, who signed off the building 12 years ago, did not notice the panel was not going to be attached properly.
Mr McCarthy says the council should have picked up on the design fault, and more emphasis will be put on getting engineers' inspections peer reviewed.