The Burlington, Ont.-based musician, who is seven months pregnant, said it happened while she and her nearly two-year-old son were on a United plane operated by regional carrier SkyWest Airlines on Wednesday.
They were on the tarmac to fly from San Francisco to Vancouver. Her son is still considered an infant by the airline's standards and therefore was able to sit in her lap free of charge.
Before leaving the gate, her son was tired and was "crying really loud and squirming," said Blackwood.
That's when a flight attendant told her: "You have to control your child."
"The only thing I can do to stop him from moving around is hold him with my arms, which was what I was doing," Blackwood said in a telephone interview on Thursday.
"I said, 'OK, yeah, absolutely.' ... I would never refuse to do anything on an airplane," she added, noting she's on tour with the band and frequently flies to perform.
"I don't want to cause a scene, ever, it just makes my life harder."
Blackwood said she was in a window seat and apologized to the man sitting beside her.
"The flight attendant came back up to me again and told me that if I couldn't control my child, they would ask me to leave the plane," she said.
"I didn't really know what she meant by 'control my child.' I mean, he's not an animal, you can't sedate children.
"I had him in my lap and he was screaming, he was loud, but I had him in my lap and I was holding on to him."
Blackwood said her son cried for about seven minutes and fell asleep as they were taxiing on the runway. But before takeoff, the plane returned to the gate.
Blackwood said the pilot claimed they needed to get more fuel but when they got to the gate, an airline representative asked her to leave the flight.
"At this point I was in tears but I just said, 'OK,'" she said.
"I woke up my son up and as I was leaving there were a few passengers that stood up and said, 'This is ridiculous, I can't believe you're doing this to her.'
"I actually had one lady on the flight gather some emails for me of the other passengers, and while she was doing that they also threatened to kick her off the plane."
SkyWest said the airline made the decision to remove Blackwood and her child from the flight "based solely on safety concerns."
"Despite numerous requests, the child was not seated, as required by federal regulation to ensure passenger safety, and was repeatedly in the aisle of the aircraft before departure and during taxi," SkyWest said in a statement.
"While our crews work to make travelling safe and comfortable for all travellers, particularly families, the crew made the appropriate decision to return to the gate in the interest of safety."
But Blackwood said her son was not in the aisles and was "fully asleep" by the time they had returned to the gate.
"I had a window seat, there was a gentleman beside me, there's no way he could've been running around in an aisle, because it was impossible," she said.
Blackwood said a United representative arranged for her and her son to get on a later flight, but she would "love compensation of some kind."
"It turned out to be a 12-and-a-half, 13-hour travel day that should've been a five-hour travel day and it was totally unnecessary and ridiculous."