On board the Papal plane -- Pope Francis has warned that expectations for an upcoming landmark Vatican summit on clergy sexual abuse should be "deflated," as the problem of abuse is unlikely to be resolved through it. The pontiff's move to lower expectations may disappoint some Catholics, particularly in the U.S. where the last year has seen a string of revelations about senior church leaders covering up abuse.

CBS News correspondent Seth Doane was on Pope Francis' overnight flight from Panama back to Rome, during which Francis held a news conference for reporters in the cabin before heading back to the front of the plane, leaving journalists to translate and digest what he'd said.

He laid out three goals for the February 21-24 Vatican summit, and said the focus should remain squarely on them. Francis said he hoped to make church leaders across the globe understand the pain sexual abuse inflicts upon victims, teach them how to properly investigate reported cases, and develop protocols for the entire church hierarchy to use in any alleged instance of abuse.

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"Let me say that I've sensed somewhat inflated expectations," he told the journalists. "We have to deflate the expectations to these three points, because the problem of abuse will continue. It's a human problem."

He said the first step is simply to be aware of the problem – and noted that in some cases, bishops still don't know what to do when they encounter abuse.

Doane said journalists on the papal flight were not allowed to ask Francis follow-up questions, but one of the natural ones would be how some bishops can still be unclear about, "what should be done?" If it is true that such confusion still exists, can that not be considered a grave failure of the church?

The pope also re-affirmed the official church position on several issues. He spoke against abortion, but referred to difficult conversations he'd had in the confessional and acknowledged the emotional pain of women who elect to have the procedure.

He was very strong on reaffirming his belief in celibacy for priests, but he also acknowledged the debate as to whether elder, married men could be ordained in some very rare situations, particularly in remote places where there was simply a shortage of available clergy.

On the crisis in Venezuela, where the Speaker of the National Assembly has launched a bid -- backed by the U.S. and a raft of other nations -- to take over the presidency from current President Nicolas Maduro, Pope Francis didn't publicly take sides. He did express his solidarity with those suffering through the crisis, which has left about 15 people dead in recent weeks, and said he was "terrified of a bloodbath" if a political solution isn't reached.