A father who lost his whole family in the Ethiopian Airline crash in March, said he misses them "every minute of every day".
Paul Njoroge said he has "nightmares about how (his children) must have clung to their mother crying" during the doomed flight.
His wife, three children and mother-in-law were on the Boeing 737 Max that crashed after take-off.
The loss of the Ethiopian Airlines' flight was the second fatal accident involving a 737 Max in five months.
A near identical aircraft, owned by the Indonesian carrier Lion Air, went down in the sea off Jakarta in October 2018.
The 737 airplane model has been grounded since then.
Boeing's decision not to ground the 737 Max after the first crash is now under scrutiny.
In emotional testimony to US Congress, Mr Njoroge said: "All I could think about was the 737 Max struggling to gain height and eventually diving to the ground, killing my whole family and 152 others. Every minute of every day they would be all around me, full of life and health. I miss them every minute of every day."
He said the airplane manufacturer - which has apologised publicly to the victims' families - had not apologised personally.
"Boeing have not apologised to us personally. No letters. They have not reached out to us at all.
"They appear on cameras to apologise to us," he said.
Also sitting at the witness bench with Mr Njoroge was Michael Stumo whose 24-year-old daughter, Samya Rose Stumo, was also killed.
'FOREIGN PILOT ERROR'
They are part of a group of families who are pushing Boeing, the Federal Aviation Administration (FAA), and the US government for answers.
"On April 4, three weeks after the deaths of my family, in what I have since learned is a shameful pattern of behaviour by Boeing and airplane manufacturers, Boeing shifted focus from the root cause of the crashes - the design flaws in the 737 Max and MCAS - and started talking about 'foreign pilot error'," Mr Njoroge said.
Congressman Sam Graves at a hearing in Washington in May argued that "facts in the preliminary report reveal pilot error as a factor".
The discussion about foreign pilots being responsible for the crash has angered the families.
Mr Njoroge told the hearing: "Would they have used the term "domestic pilot error" if the crash happened in the United States? The term 'foreign pilot error' is utter prejudice and a disrespect to pilots and Boeing customers across the world".
Boeing and its relationship with the FAA is also a key battle line for the families.
Under an arrangement formed in 2005, the FAA delegated to Boeing the authority to perform some safety-certification work on its behalf.
The families said they believe the FAA "recklessly left Boeing to police itself".
"If Boeing's wrongful conduct continues, another plane will dive to the ground killing me or you or your children or other members of your family. It is you who must be the leaders in this fight for aviation safety in the world," said Mr Njoroge said.
After the crash in March, it was revealed by insiders that pilots had trained to fly the 737 Max, a new version of the 737, after completing an iPad course that lasted an hour.
The "families demand that the 737 Max 8 be fully re-certified as a new plane because it is too different from the original certified plane. We demand that simulator training be required," Mr Njoroge told Congress.
The biggest question in global aviation is when will the 737 Max begin to fly again? Just this week, major airlines in the US confirmed they'll be out of service until at least November, maybe even 2020.
In response to the points made at the congressional hearing, Boeing said: "We truly regret the loss of lives in both of these accidents and we are deeply sorry for the impact to the families and loved ones of those on board.
"These incidents and the lives lost will continue to weigh heavily on our hearts and on our minds for years to come. We are committed to working with the communities, customers and the aviation industry to help with the healing process."