The 5th Region's officers weren't conspiring but their sympathies were on one side. In their commander's absence, at 22:50 they were ordered to move the 5th Mech Recon Squadron to the border with São Paulo, as Kruel's position was dubious. The squadron was told nonspecifically to just be ready to take orders. In a sense they were entering mutiny.
Ladário and Silvino's plane passed Curitiba at 23:45 and by the former's account, which is what most sources repeat, couldn't land for lack of visibility. That is true, but not because of the weather; the officers arranged to black out the landing field. The pilot could have settled for a nearby airbase whose commander was still legalist; why he didn't is unknown and there's no information at all on it.

Galhardo promised he'd arrest Ladário on arrival. He didn't and capitulated his command at 02:50.
Ladário's proclamation had a curious tone: "the satanic force of privileges won't snatch from the Brazilian people the banner of reforms, for it we'll fight, army and people, always united". It wasn't just a rallying call of obedience to the legal commander-in-chief but to an ideology, a political faction's program. No source really comments on it but I find it an example of radicalization. And it had a rationale, the other side was also fighting ideologically and radicalization was how a leftist base could be mobilized.
Adalberto fled to Cruz Alta, deep in the hinterland, where his division had an artillery group and the 17th Infantry Regiment. Ladário issued requisitioning decrees which overrid Meneghetti's and handed the radios to Brizola, who as in 1961 launched a legalist media campaign.

At dawn the 5th Region ensured the IInd Army was on its side and then at 06:50, led by general Dário, the interim commander, told its commanders it'd fight on the rebel side.
Thus by morning it was a rebel defeat in the core and victory in the buffer zone.