Wreaths will be laid at a memorial garden in Lockerbie, Dumfries and Galloway, where the wreckage of the bombed Pan Am Flight 103 came down on the night of December 21 1988.
Eleven people died in the town, along with the 259 passengers and crew on board the New York-bound plane which had set off from Heathrow.
A low-key service on Friday will see victims’ relatives join members of the community who assisted in the aftermath of the atrocity, the largest act of mass murder committed on British soil in recent history.
The only person convicted of the bombing, former Libyan intelligence officer Abdelbaset al-Megrahi , died in 2012 after being released from Greenock jail on compassionate grounds.
Canon Patrick Keegans, parish priest in Lockerbie at the time of the disaster, will speak at Mass led by Bishop William Nolan at the town’s Holy Trinity Roman Catholic Church on Friday evening.
Mr Keegans survived as his street, Sherwood Crescent, was showered with debris that destroyed homes and killed his neighbours.
Now semi-retired and based in Prestwick, he said memories of that night would never leave those who lived through it.
The 72-year-old said: “It doesn’t go away, it stays with people.
“Especially those who have lost family and those who have been involved in any sort of way.
“It’s part of our life now. We live with it. We don’t live miserable, sad lives but there’s an undercurrent all the time.
“Those memories of the night and subsequent memories, they stay with me, they are part and parcel of who I am now.”
The majority of those on board the jet were American citizens, including 35 students of Syracuse University in New York State.
A memorial will be held at the university and at Arlington National Cemetery in Virginia, where a cairn made from Lockerbie stone stands in memory of those who died.
A 30th anniversary service will also be held at FBI headquarters in Washington DC.
Kara Weipz, from New Jersey, lost her 20-year-old brother Rick Monetti, a Syracuse student, and will attend the ceremony at Arlington, where around 500 people are expected to gather. She was 15 and home sick from school the day of the disaster, and had to break the news to her parents when they returned from work.
The mother of three, who is president of the Victims of Pan Am Flight 103 group, said ahead of the anniversary: “I don’t think it gets easier, I think it’s just different.
“The sadness takes different forms. I have an 18-year-old who in the fall (autumn) will be heading off to college, so I think now how my parents must have felt.
“But myself and others are also looking at what we’ve done in 30 years - look at this awful thing that happened to us, and look how we’ve come together, how we’ve enacted change, created our own family and been there for one another.”
She added: “We can’t change things, we can’t bring them back, but we can look at the fact that we have always honoured them with the way we live our lives and the things we do, and that’s the best way we can remember them, 30 years later.”
Back in Scotland, a Walk of Peace has been arranged by the Church of Scotland on Saturday to remember those who died.
People will climb Burnswark Hill near Lockerbie in silence following a special service at Tundergarth Parish Church the previous day.
The church is close to where the nose cone of the plane, Clipper Maid of the Seas, came to rest.
The Rev Adam Dillon, Clerk to the Presbytery of Annandale and Eskdale, said: “The horror of the night will live on in the memories of those who lived in Tundergarth and Lockerbie. This 30th anniversary gives the communities a chance to focus on looking forward - drawing on the resilience and temerity that has been required of them since 1988. My thoughts and prayers remain with all affected.”