Lisa Gibson from Colorado was 18 when her brother, Ken, was blown up in an attack on Pan AM flight 103 over the southern Scottish town of Lockerbie.
She had come home from college for Christmas and was looking forward to seeing her brother, a US soldier, when the news broke.
The bombing killed 270 people in the air and on the ground.
On Friday, victims' relatives will mark the 24th anniversary of the attack in a memorial service at the Arlington national cemetery - but Ms Gibson will not be among them.
She has chosen to spend her Christmas holidays in Libya, the country said to have been behind the bombing.
"At the heart of terrorism is hate and fear, and the only way to effectively fight it is to walk in the opposite spirit with love and forgiveness," she told the BBC.
"I refuse to be crippled with bitterness and respond in kind. I wanted to take the moral high ground," she said.
It was in this spirit that Lisa met and personally forgave the Libyan leader, Muammar Gaddafi, in 2009, for what both America and Britain believe was a state-sponsored act of terrorism.
She previously wrote in similar terms to the only man ever convicted over the atrocity, the Libyan agent Abdelbaset al-Megrahi.
He sent a grateful reply from his prison cell in Scotland. In the letter, dated 2 July 2004, he also denied responsibility for the Lockerbie bombing.
"The court found me guilty based on false and unsound evidence," he wrote. "I pray day and night that God helps me to prove my innocence."
Megrahi died from cancer earlier this year having been released from jail on compassionate grounds - a decision that angered many Lockerbie relatives in the US and their government.
Ms Gibson takes a different view.
"I think that holding onto vengeance just causes the cycle of hate to continue," she said. "Ultimately, the decision to forgive and move towards reconciliation is, I think, much more impactful."
Lisa, who is a committed Christian, has set up a not-for-profit organisation to promote peace and reconciliation.
Instead of taking a Christmas holiday this year, she is giving her time to help Libyans as they rebuild from the revolution that toppled Gaddafi.
She is teaching conflict resolution to local leaders in the city of Benghazi, where the US ambassador and three of his colleagues were murdered in September.
Files to be released
The new government in Libya has struggled to establish security in the aftermath of last year's conflict.
The Libyan ambassador to Britain, Mahmud Nagua, told the BBC that only when the country was stable could it face up to past horrors like Lockerbie.
"When we have enough time, enough security and stability, all these files will be open and everyone will know what happened," he said.
Meanwhile, the British government has said that it is pressing Libya "for swift progress and co-operation" on a request from Scottish police to question new suspects in Libya.
The politics and police work are not Lisa's primary concerns.
She is more interested in offering practical help to ordinary Libyans.
After 24 years of living with her loss, this is Lisa's way of making sure some good comes from her brother's death.