On Saturday night police received a treatment from a pilot to crash a light plane into the tower, which dominates the skyline of New Zealand's largest city.
The threat followed what officials described as a "domestic situation."
The pilot, identified by police as David Turnock, 33, eventually ditched the single-engine Cessna plane into the sea at Auckland's Kohimarama Beach.
Police arrested Turnock on Monday and charged him with unlawfully taking an aircraft, after he was released from a hospital. He was to appear in court later in the day.
Acting Auckland City district commander Gavin Jones said police had no way of preventing the airplane from hitting the tower, but that it was too small to topple the building.
"But having said that, if for example, the plane headed for the observation (decks) or the restaurant, there was potential for a major disaster," he said.
Police cleared 500 diners from two tower restaurants as the plane flew near the needle-like building.
"I don't believe it would have taken the whole Sky Tower out," Jones said.
Architect and tower designer Gordon Moller said a plane hitting the lower reinforced concrete shaft would cause nothing more than surface damage.
If it flew into the "pod" with five or six levels of observation decks and restaurants it would cause damage to the aluminum cladding and windows and, possibly, a fire, he said.
The tower was primarily designed to withstand things like fire, wind and earthquake. It was hard to design for a "severe impact," he added.