A service is being held in Aberdeen to remember the 167 men who died in the Piper Alpha disaster 25 years ago today.
The North Sea oil rig exploded on the night of 6 July 1988, resulting in a fireball that engulfed the structure.
A Sea King helicopter from RAF Lossiemouth was due to mark the start of the service with a fly past at 11am.
The remembrance service is taking place at the Memorial Garden in Aberdeen's Hazlehead Park, which has undergone a £150,000 upgrade.
Prime Minister David Cameron said in a message to industry body Oil and Gas UK: "The 25th anniversary of the Piper Alpha disaster is a fitting moment to mark the skill, bravery and dedicated professionalism of all those who work offshore.
"We will never forget the 167 who lost their lives. And my thoughts as Aberdeen remembers its loss are with their families and loved ones, the survivors and all those involved on that tragic night."
First Minister Alex Salmond said: "The 25th anniversary has rightly had a substantial emphasis in making sure that the new generation of offshore workers understand the importance of Piper Alpha in creating the current offshore safety regime.
"However, given that the oil industry will be with us for the next half century and more, we also have a responsibility to ensure that new generations of Scots understand the significance of the world's worst offshore disaster."