Pilots flying the two Boeing 737 Max jets that crashed in the past year were bombarded by multiple warnings that the flights were going dangerously wrong.

Boeing has said the pilots should have been able to swiftly diagnose the problem and follow a long-standing procedure to fix it.

But a report Thursday from federal accident investigators questions whether Boeing and the Federal Aviation Administration underestimated how a blizzard of visual and auditory warnings would slow the pilots’ ability to respond quickly enough to avoid disaster.

The National Transportation Safety Board issued seven recommendations stemming from its role as an adviser to investigations of the crashes in Indonesia and Ethiopia, which together killed 346 people.

It will be up to investigators in those countries to determine what caused the accidents. Preliminary reports have pointed to an anti-stall system that kicked in based on faulty sensor readings and pushed the noses of the planes down.

The NTSB said Boeing assumed that pilots flying the Max would respond to an automated nose-down push by taking “immediate and appropriate” steps. Federal regulations allow manufacturers to make such assumptions, and Boeing even used test pilots in flight simulators to check its assumptions.

Boeing presented highly trained test pilots only with a single alert indicating a condition known as runaway stabilizer trim, which can be triggered by an anti-stall system called MCAS, safety board officials said. They said Boeing failed to consider that an underlying problem like sensor failures — which triggered MCAS in both Max crashes — would set off several alarms.

The Max has been grounded worldwide since March, shortly after the second crash.