It was a year ago this week when the second Max crashed in Ethiopia, killing all on board.

And now today Ethiopian investigators have released a new interim report on the crash.

Our Geo Benitez is here with more Good evening to you.

Hey, Lindsay, Good evening is you.

This is what this was the crash that led to the worldwide grounding off the 7 37 max.

And now today, Ethiopian investigators blaming Boeing for those design flaws.

This as so many families remember their loved ones.

One year later, we begin tonight with the deadly plane crash, the new Boeing jet that went down overseas.

It's the news that shook every traveller around the glue.

Just six minutes after takeoff, Ethiopian Air Flight 302 plummeting near the Ethiopian capital of Addis Ababa.

The plane shattered in pieces 157 killed, including eight Americans seen painfully familiar because it was the second Boeing 7 37 max involved in a catastrophic crash in less than five months.

In October 2018 Lion Air Flight 6 10 also crashed off the coast of Indonesia into the Java sea, leaving heartbroken relatives as crews sifted through floating and underwater wreckage for clues into what went wrong on with the crash of the Ethiopian air flight history.

Repeating itself.

Investigators going through the rubble of this Ethiopian field turned graveyard first crash in Indonesia was initially blamed on pilot error despite the fact that just the day before a pilot reported struggling to keep control of the same plane.

But now the realization began flying around the globe.

Something could be wrong with the plane itself, once Boeing's fastest seller.

In my mind, there was such trust in the Boeing brand, such trust in the ability of this company to build great safe airplanes that even after the second airplane went down with very similar characteristics, hard to think about.

Wow, maybe it was a design problem.

One by one, nations taking the plane out of commission and then U.

S regulators to we're gonna be issuing an emergency order of Prohibition to ground all flights of the 7 37 max A on the 7 37 max nine and this week, a year later, 400 brand new Max planes are still sitting like untouched artifacts and Boeing, after making adjustments, is trying to convince the world the plane is safe.

Paul Gerardi lost his entire family in the Ethiopian crash.

My wife and my mom and loan knew they were going to die.

They had to somehow comfort the Children during those final moments, knowing they were all there lost in the last year.

Those left behind going to Capitol Hill trying to prevent something like this from ever happening again.

Tomorrow it can be you can be or families.

It can be your wives and your kids.

Here's what investigators believe happened in both crashes off.

Faulty Sensor Sent bad data to a system called M casts the maneuvering characteristics.

Augmentation System.

Just look at how much bigger the engines on the max are compared to the previous 7 37 model, which at the time was the best selling airliner in certain circumstances, the larger repositioned engines cause the max to pitch up and full thrust.

The nose tended to point to far upwards that M caste system designed to help stabilize the plane.

But in this ABC News simulation watch the plane's erratic behavior that faulty sensor caused the system to misfire, forcing the plane's nose down, over and over again, even as pilots thought to gain altitude.

Over 80% of all mishaps and commercial aviation are caused by humans making errors.

It is the human being that is the problem, not the airplane.

And what happened in the max is bowing.

Tried to design something in that would help the human being rather than designed something in that would help the machine fly the machine better.

The system was not mentioned in the Plains manual, a critical document for pilots in the air.

But after the first crash, the FAA issued a warning to pilots saying that incorrect sensor data could lead to a loss of control and a crash in the cockpit.

Multiple alarms going off like this, potentially causing confusion in the cockpit.

The National Transportation Safety Board, saying this was a factor in the crash.

It's very understandable why they were overwhelmed, but that part of it gets covered when you do the basic emergency procedures.

Members of Congress accused the FAA of being too cozy with Boeing, saying the FAA failed to ask the right questions.

We've interviewed and spoken with FAA employees blowing whistle blowers among others thes documents, e mails, interviews are crucial to our investigation, which is uncovered.

A broken safety culture within Boeing and an FAA that was unknowing, unable or unwilling to step up, regulate and provide appropriate oversight of Boeing lawmakers grilling Boeing, Accusing the manufacturer of putting profit over safety but is troubling to hear that Boeing may have skirted the FAA certification process over a desire by airlines.

TOA have more fuel efficient planes, but without pilot training, Boeing admitting it made mistakes.

Why didn't we ground that aircraft a lot sooner?

So another tragedy wouldn't happen if we knew everything back then that we know now we would have made a different decision.

But the company's saying, safety is and always has been.

It's highest priority.

When the Max returns to the skies with software changes to the M past function, it will be among the safest airplanes ever to fly Boeing, ultimately firing its then CEO Dennis Muilenburg, even though he had every intention of staying.

These two accidents happened on my watch.

I feel responsible to see this through the year long grounding costing Boeing and the airlines billions Boeing eventually shutting down the production line But now tonight, how does Boeing recover?

And will the max ever fly again?

The 7 37 max, or whatever it's called in the future, will be a great airplane.

It is going to take time.

They're gonna have to earn the trust of the flying public.

Just days ago, when a preliminary report, lawmakers concluded that production pressures, design failures and a lack of transparency from Boeing, coupled with a failure of oversight from the FAA, led to the two fatal plane crashes that killed hundreds, nearly 350 people mothers, fathers, sons and daughters who should still be alive.

Yes, so tragic.

Now, in just a few weeks, Boeing plans to conduct with FAA pilots the certification flight test that is expected there in just a few weeks.

But they have months of work ahead.

Lindsay, because Boeing says that they do plan to fly the max with passengers by the sun, and over the weekend we learn of another potential setback.

Yes, so, basically, the FAA told Boeing that they need to make some changes to the max is electrical wiring, but still bowing insists they plan to fly the plane.

And so the report also suggests that the pilots tried to re engage the automated system, right?

Yeah, And aviation experts, every aviation expert, we speak with Lindsay.

They basically say, When you get that automated system and you have a problem, you turn it off, you leave it off, and then you fly that plane manually.

That didn't happen here.

For some reason, the pilot's turned that automated system back on, and the automated system is what had the problem.

Geo Benitez.

A pleasure to have you with us in studio tonight.

Hi, everyone.

George Stephanopoulos Here.

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