The grieving father of the American Airlines copilot who was killed when his plane collided with an Army Black Hawk helicopter in January has said the tragedy was 'completely preventable' - and called for the US Army to apologise. Samuel Lilley, 28, was the copilot onboard American Airlines flight 5342 when it collided with a military helicopter in Washington DC, sending both plunging into the Potomac River and killing all 67 people across both aircraft. His father Tim Lilley told Good Morning Britain this morning, in an interview with his wife Sheri: 'This was a completely preventable accident. It happened 100 per cent because of complacency.' It comes ahead of the first public hearing in Congress today about what happened to cause the deadly midair crash above the American capital. It will see the body conducting ongoing investigations into the crash, the National Transportation Safety Board, and leaders of the federal and Army aviation departments face a grilling by lawmakers in the Senate. Mr Lilley said: 'The Army hasn't even offered one single rose to lay on my son's grave. They really need to take some responsibility, apologise for their part in this accident.' In a tragically ironic twist, the father, who is a veteran, spent 20 years flying the same kind of military helicopters that killed his son. He said: 'We are never going to be able to fill the hole. He deserved a much longer life than he had.' The regional flight Mr Lilley was copiloting had come from the city of Wichita, Kansas, and was at around 8.15pm on January 29 beginning its descent into Ronald Reagan Washington National Airport with 64 people onboard. The plane crashed with the helicopter, which had three soldiers onboard on a training flight, at around 8.45pm. It was the deadliest plane crash in the US since 9/11. Investigations are ongoing into the accident that killed all 67 people involved, after both aircraft plunged into the icy river below - but all non-essential helicopter operations around the airport have now been banned as of earlier this month. Mr Lilley said: 'I still wake up in a cold sweat thinking about the condition of my son in that river. It was a gruesome scene.' The father, who now has a tattoo of a plane and the number of the flight his son was copiloting, continued: 'I take solace in the fact that he went fast.' His wife Mrs Lilley dubbed the day they lost their son as 'the worst day of our lives': 'He was just genuinely very caring, he was very emotionally mature for someone who was 28.' Their son was engaged and planning to get married this autumn. He was fully certified to fly commercial planes just two years ago, undergoing 1,500 hours of flight time to earn this. It comes after the family of a father-of-three killed in the plane crash filed a $250million pre-case claim against the Federal Aviation Administration and the US Army last month. Passenger Casey Crafton, 40, was one of the 67 killed in the fireball crash. A pre-case claim is a formal letter sent before starting court proceedings in an attempt to resolve a dispute without going to court. It was lodged by aviation law firm Clifford Law Offices on behalf of Mr Crafton's family. Attorney Bob Clifford said in a statement: 'Casey was an incredible human being. He was a giver, a loving husband, and father. 'He enjoyed coaching his boys on their youth soccer and Little League baseball teams. They will be grieving him for the rest of their lives that will never be the same.' Clifford Law Offices said the National Transportation Safety Board had reported that staffing in the air traffic control tower was 'not normal' at the time of the plane crash. The federal government has six months to act on the claims, and if rejected or not acted upon, the Crafton family will have the right to file lawsuits, the firm said.