He travels as often and as far away from the East Coast as he can to be the voice for the fallen friends he lost that day. In the years since, from suicide and 9/11 cancers, he is still fighting to keep that promise we all made 18 Years ago, to never forget.
The pain from Sept. 11 can be summed up by the sounds of the eerie wail of firefighter motion alerts still going off, days after the twin towers were reduced to piles of ashes and concrete.
"Those were chirping by the hundreds because so many firemen were buried in the rubble. And we knew those were attached to our brothers who were just killed," said Brown.
He is one of the few 9/11 survivors from New York Fire's Special Ops Command.
"Our office was the 23rd floor of 7 World Trade Center," Brown said.
"I saw some bad stuff, man," he added.
Remembering courage on 9/11
He also saw remarkable acts of bravery.
"My best friend, Capt. Terry Hatton from Rescue 1, one of the most elite firefighter units in Manhattan, I saw him in the lobby of tower one," he recalled. "He wrapped his arms around me and squeezed me to his chest and said, 'I love you, brother. I may never see you again.' He kissed me on the cheek then went up the stairwell with his men."
"He knew it, right? He knew it!" he added.
"My friend Chris Blackwell, same thing. We always kissed on the lips. It was just what we did. And I kissed him on the lips and he said, "Timmy, this is really bad!'" Brown continued. "And Chris turned around and he went in the stairwell, and he went up too."
"They all thought they were not coming back. They still did it," he said.
Then, the second plane hit.
Brown and Asst. FDNY Chief Donald Burns were the first ones into the south tower when they came across some people trapped in an elevator.
"That elevator car had free fallen 70 floors because the cable got snapped by the plane," Brown said.
"They were screaming in pain because the elevator pit below them was full of jet fuel and it was on fire, and they were right above it, and they were getting burned," he said.
Running outside for help, Brown heard an unmistakable sound and took cover in the Marriott Hotel next door.
"We were about 20 feet from the door of the south tower when it collapsed," Brown said.
"It was pitch black. You couldn't breathe, you couldn't see."
"I know from experience as a firefighter that the strongest part of a building is a vertical column. I found one, and I grabbed onto it and held on for dear life and just waited to be crushed," Brown said.
"I thought about how unfair it was. I couldn't hold my family one more time," he added.
Somehow, Brown and a small group of about 35 survivors defied the odds, sustaining what researchers later determined in a series of tests were 185 mph winds in that little pocket in the rubble.
“This evil attack on America and on humanity is still killing us."
-Tim Brown, 9/11 FDNY Survivor
Aside from the 343 firefighters and 71 police officers who died that day, other first responders succumbed to suicide, unable to live with the pain.
“I would not have survived without some pretty intense therapy,” Brown said.
9/11 still claiming victims
And then, there are those we are still losing, to 9/11 cancers.
Ray Pfeifer, one of the three men the 9-11 Victims' Compensation Fund is named for, was Brown’s close friend.
"He chased congressmen and senators around the halls of the Capitol in his wheelchair!" Brown said of Pfeifer's persistence.
Brown cannot lobby Congress since he's now working a federal job with national security.
He was still in the Rose Garden when President Donald Trump signed the bill into law two months ago, saying it was time "to support our 9/11 heroes and care for their families and to renew our eternal vow to never ever forget."
"We have over 2,500 sick right now. Just the fire department!" Brown said.
He says we cannot forget the many civilians were also exposed.
His friend, Michael Brown, was a New York firefighter for four years.
Right after the attacks, he drove cross country to come back and help find his missing brother, FDNY Capt. Paddy Brown, from Ladder 3.
"Michael spent a lot of time in the rubble, breathing in all that toxic air and now Mike is very sick," Brown said.
"And the one that catches in my throat, is the kids who went to school there," Brown said of some of those now 20-something students who are also being diagnosed with 9/11 cancers.
He says he will fight for them too.
"We have to always remember who did it and why they did it. America has to be vigilant against that evil ideology because if we're not vigilant, it's going to come back and visit us again," Brown said.
"We have to defend America. We have to defend freedom because that's really what they wanted to take away from us," he added.
As painful as this day is, Brown welcomes the reminders, not to move on.
"It's emotionally difficult, but it's so important that as long as I have a voice to use it, to talk about the heroes of the day," he said.
He wants to make sure we never forget.