The global grounding of Boeing's 737 Max jets will cost the company more than $1bn, the company said on Wednesday.
Preliminary reports indicate that faulty sensor readings triggered MCAS and pushed the nose down in both the October 29 crash of a Lion Air jet off the coast of Indonesia and the March 10 crash of an Ethiopian Airlines Max.
Boeing is also halting stock buybacks. It plans to issue new guidance at a future date.
"I can tell you with confidence that we understand our airplane, we understand how the design was accomplished, how the certification was accomplished and we remain fully confident in the product that we put in the field", Chief Executive Dennis Muilenburg said in a conference call with analysts.
Muilenburg insisted on Wednesday that "there was no surprise or gap or unknown here or something that somehow slipped through the certification process" but added that a board committee would review the company's aircraft development processes.
Excluding certain items, Boeing said its core earnings fell to $3.16 per share, in the quarter from $3.64 per share, a year earlier.
The US aerospace giant reported $2.1 billion in profits in the first quarter, a decline of 13.2 percent from same period a year ago due in part to the $1 billion hit from the 737 program.
Revenues dipped 2.0 per cent to US$22.9 billion.
Abandoning its full-year financial forecasts as a outcome of the disruption, Boeing said the guidance "does not reflect the 737 Max impacts ... due to the timing and conditions surrounding the return to service of the 737 Max fleet".
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A fuller picture of how much the grounding will cost Boeing and how it plans to fix its image with the flying public will not emerge until the end of the second-quarter as 737 production cuts did not begin until mid-April.
Boeing also booked unspecified charges related to developing a software fix for an anti-stall system that Boeing has acknowledged played a role in both crashes, and pilot training. That flight is expected any day. The company could also face costs from government probes and settlements with victims' families.
UBS analyst Myles Walton said the company's estimate of a $1 billion hit from the Max situation was "likely below the low end of anyone's thinking".
The 737 Max is an updated version of a plane that has been a mainstay of passenger travel since it first flew in the late 1960s.
Boeing said it is "making steady progress" on the software fix and has conducted more than 135 test flights as it works with global regulators and airlines on the system.
"We're confident in Boeing's ability to weather the storm", said Tom Kennedy, head trader and portfolio analyst at New England Investment and Retirement Group, which has $580 million in assets under management.
Analysts have varied in their assessments of the impact to Boeing's long-term prospects.
Boeing's commercial aircraft division managed to offset the impact of the Max 8 groundings by increasing sales of its 787 planes.
However, some caution that Boeing's reputation has been damaged by the crisis that could deteriorate further with any additional missteps.