"As we speak, Ethiopian Airlines has lost a revenue of $550 million (504 million euros) including April," Tewolde Gebremariam told a press conference
Alalo died while en-route from Italy, where she had attended a conference.
Security forces blocked journalists from attending the ceremony at the site, though vehicles transporting families could be seen heading there.
The October 2018 crash of a Lion Air 737 MAX in Indonesia killed 189 people, while 157 died in the accident in Ethiopia five months later.
Other victims' family members have also appeared at congressional hearings, and numerous lawsuits have been filed against Boeing.
The crash came after another Boeing 737 MAX of Indonesian company Lion Air crashed in October, killing 189 people on board.
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One Ugandan, Commissioner of Police Christine Alalo, was among the 157 people killed on board the doomed flight last month.
Ahead of this day of reckoning, the company launched a campaign to convince the flying public that it is addressing the issues with the MAX
"Let me be clear: Ethiopian Airlines believes in Boeing. They have been a partner of ours for many years," Tewolde GebreMariam wrote in a statement.
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