Grieving relatives tossed flowers into the sea on Tuesday where an Indonesian Lion Air jet crashed a year ago, killing all 189 on board, after a final accident report pointed to plane design flaws as a key factor in the disaster.The crash on October 29 last year was followed months later by a second accident - involving the same model Boeing 737-Max aircraft - when an Ethiopian Airlines plane went down with 157 people aboard, leading to the global grounding of the US planemaker's entire MAX fleet.Tuesday's ceremony was closed to media, but video footage supplied by relatives showed victims' family members praying and casting flowers into the Java Sea where the plane dived moments after takeoff from Jakarta.Some were stoic, but others broke down as they remembered loved ones, with women in Lion Air flight attendant uniforms seen embracing grief-stricken relatives."I hope that a year since the incident Lion Air will heed all of its obligations to the victims' families," Anton Sahadi, who lost his cousin in the crash, told AFP on Tuesday.On Friday, Indonesia's National Transportation Safety Committee issued its final crash report, which said a Boeing design flaw, inadequate pilot training and poor flight crew performance contributed to the deadly accident.It highlighted design and mechanical problems with the MAX model's Manoeuvring Characteristics Augmentation System (MCAS), an anti-stall mechanism, that pilots in both disasters had struggled to control as their jets careered downwards.The system's certification by US regulators was "inadequate", the report said.On Tuesday, some grieving relatives opted not to attend the sea ceremony."Whatever happened, happened - I cannot change it," said Aldhi, who goes by one name, as he remembered his lost wife at a private prayer session at his home in Jakarta. Yoda, who like many Indonesians also goes by one name, visited a Jakarta cemetery to remember his best friend who died in the crash."That night I stayed at his place. I woke him up because he had to fly in the morning," Yoda told AFP."His last words to me were: 'I'm leaving now, man'."