Face of Nation : Rosa King, 33, was killed by a Malayan male called Cicip at Hamerton Zoo Park in Cambridgeshire on 29 May 2017.
The zookeeper had not realised that a metal slide designed to isolate the animal had been left open, her inquest heard.
Ms King died at the scene after suffering traumatic injuries including a severed spinal cord.
She had entered the enclosure to clean its viewing windows before the zoo opened for the day at 10am.
Her body was discovered by a zoo visitor who looked into the enclosure from the public viewing area and raised the alarm at around 11am.
Police scenes of crime officer Nathan Searle described seeing a “large bloodstain on the ground, a set of keys and a blood-stained paw print” alongside a wet cloth, a squeegee and an upturned bucket near the keeper’s gate to the enclosure.
Head keeper Katherine Adams said she believed Ms King, who was working alone, was attacked as she tried to leave the paddock.
She added that Cicip may have stalked Ms King after she entered the enclosure and attacked her five minutes later.
Nicholas Moss, Cambridgeshire’s assistant coroner, said a metal vertical slide, designed to isolate tigers from keepers in the enclosure, was found to be open immediately after the attack.
A metal protective gate used by keepers to access the paddock and a wooden gate to stop members of the public entering a service area were also found to be open.
A police investigation found no mechanical faults and Sergeant James Thorne said it was easy to spot the position of the slides.
The zoo’s procedure was for a keeper to locate the tigers and ensure they were isolated by metal slides before entering the enclosure, the inquest heard.
The jury, alongside its conclusion of accidental death, said that the zoo’s procedure “depended entirely on the keeper reliably following their training”
Mr Moss said: “The death in this case occurred despite the fact there was a simple system and keepers such as Rosa who were safety conscious knew what the system was and knew what the risk was.
“While it was unexpected for Rosa not to follow that system it seemed to be due to human error, of which we are all prey.”
Elizabeth Yeomans, a senior ergonomist for the Health and Safety Executive, said earlier in the inquest that sometimes, when a person has completed a task many times before, “you look and see what you think you should see”.
Ms King may have been tired at the time, having worked 45-hours per week during the summer months and helping with night feeds for a serval kitten, a type of African cat, the inquest heard.
Colleagues described her as a “very safe” keeper who would not have taken shortcuts in her work.
Ms King’s death was ruled an accident after more than two hours of deliberation by a jury and six days of evidence.
