Sullivan, 20, a team videographer, learned of the wind advisory from weather.com shortly before practice. The football staff accessed the same website several times during the day but missed the wind warnings on the page, according to an internal report released Monday.
The university's investigation found "no one acted in disregard for safety" the day of the accident. Rather, a "sudden and extraordinary" wind and long-standing policies led to Sullivan's death, officials said.
The National Weather Service had issued a wind advisory for the day, and gusts reached 53 mph about the time of Sullivan's fall. The lift crashed through a fence and landed on a street.
"The university is collectively responsible," said the Rev. John Jenkins, Notre Dame's president. "Insofar as the president is responsible for the university as a whole, I am the individual who bears the most responsibility and I accept that responsibility."
No one was disciplined for their role in the accident, Jenkins said. The football athletic trainer, who oversees team safety, has been given a new job title and increased responsibilities.
After stiff winds forced the team to work out indoors the previous day, head coach Brian Kelly opted to practice outside on Oct. 27 and informed his staff of the decision around 10 a.m. Over the next five hours, staff members checked the weather seven times and each time found the conditions safe enough for the lifts to be used.
According to the report, the football program's policy was to keep the videographers off the hydraulic lifts if the winds reached more than 35 mph. The weather data accessed by the staff never crossed that threshold, officials said.
In keeping with international standards, the lift industry recommends grounding the equipment when winds exceed 28 mph. Notre Dame established the 35 mph threshold based on information gleaned at conferences and from other teams, the report said.
When checking weather websites, the staff saw reports of 23 mph sustained winds with 30 mph gusts prior to practice, according to the report. Computer forensics show no one on the staff clicked on a wind advisory icon that warned of possible winds exceeding 50 mph, said John Affleck-Graves, the university's executive vice president.
Eight minutes after the football staff checked the weather for the final time, the weather service reported wind gusts up to 38 mph in South Bend. There were no wind gauges on the field, so the staff depended on its own observations to determine if conditions were safe.
The staff repeatedly checked conditions before practice, but the report states it did not did check weather data again "despite those pre-practice concerns."
"According to interviews, no one perceived the wind as unusual and no one discerned that wind speeds were increasing in severity during practice," the report states.
Sullivan expressed concerns in messages posted on social media sites shortly before his death.
"Gusts of wind up to 60 mph today will be fun at work ... I guess I've lived long enough," he wrote.
While on the lift, he tweeted again. "Holy (expletive). Holy (expletive) this is terrifying," he wrote.
The report, however, suggests Sullivan may have been joking when he sent the messages.
"Notre Dame cannot conclusively determine whether Declan, himself, felt unsafe and pressured to stay in the lift," the report states.