• Lion Air Flight 610 and Ethiopian Airlines Flight 302 crashed within five months of each other despite being effectively brand new.
  • Both flights lacked two optional safety features that could have prevent the crashes, because Boeing charged extra for them, The New York Times reported .
  • They were an indicator that determines how much the plane's nose is tilted, and a light that activates when the plane's nose sensors are at odds with each other, The Times said.
  • Boeing will reportedly now make one of the features standard on all 737 Max jets. The company is also planning a new software update.

The two crashed Lion Air and Ethiopian Airlines jets lacked two safety features that could have helped prevent the disasters, because Boeing charged extra for them, The New York Times reported Thursday .

Lion Air Flight 610 crashed over the Java Sea last October, killing all 189 people onboard. Ethiopian Airlines Flight 302 crashed on March 10, killing all 157 people onboard.

Both jets Boeing 737 Max 8 planes were effectively brand new, and the crashes prompted a worldwide grounding of the plane.

Read more: Everything we know about Ethiopian Airlines' deadly crash of a Boeing 737 Max 8, the second disaster involving the plane in 5 months

These were the two optional safety features lacking on the two flights, according to The Times:

  • An angle of attack indicator, which takes readings from two devices called angle of attack sensors, which determine how much the plane's nose is pointing up or down in relation to to the air.
  • A disagree light, which activates when the angle of attack sensors conflict one another.

While the causes of the two crashes are not yet known, investigators are reportedly looking into whether an automatic system called Maneuvering Characteristics Augmentation System (MCAS), which is designed to prevent the plane's nose from tipping upwards, was incorrectly triggered, forcing the plane into a dive.

Investigators also believe that the MCAS played a role in the Lion Air crash as well.Dagmawit Moge, Ethiopia's transport minister, said the two disasters have "clear similarities."

The US Federal Aviation Administration (FAA) does not require jets to install the two extra safety features, The Times reported. Business Insider has contacted the FAA for comment.

Read more: Europe and Canada are investigating the Boeing 737 Max themselves rather than trusting the US another apparent snub of American regulators

Bjorn Fehrm, an analyst at aviation consultancy Leeham, told The Times that the safety upgrades are "critical, and cost almost nothing for the airlines to install."

"Boeing charges for them because it can," Fehrm added. "But they're vital for safety."

Business Insider has contacted Boeing for comment.

According to The Times, Boeing charges extra for a range of upgrades, including backup fire extinguishers. But many airlines opt for the cheapest model they can get, and tend to redact details of features they pay for or opt out of.

As of 2013, airlines tended to spend between $800,000 and $2 million extra per plane on various optional upgrades, The Times reported the Jackson Square Aviation consultancy as saying.

A Boeing 737 Max 8 currently costs about $121 million, according to Statista .

Boeing has said in the wake of the Ethiopian Airlines crash that it will install a software update on all 737 Max planes .

According to The Times, the firm now plans to add the disagree light to all 737 Max flights for free, but will leave the angle attack indicator as an extra option that airlines can decide whether or not to buy.

The US, Europe, Canada, and more than 50 countries around the world grounded their 737 Max jets in the wake of the Ethiopian Airlines crash.

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SEE ALSO: A cockpit voice recording from doomed Lion Air 737 Max shows pilots scoured the plane's manual to fix its fatal dive but couldn't find the right procedure in time