The last five months have seen two fatal airline crashes, Lion Air Flight 610 and Ethiopian Airlines Flight 302. Both crashes took the lives of everyone on board and now, according to a report, both planes may have been missing key safety features.

According to the New York Times, the jets were missing features that would have helped the pilots detect dangerous readings. The crafts were brand new Boeing 737 Max planes but were missing the angle of attack indicator or an angle of attack disagree light.

The apparent reason, according to the report, was the cost to purchase and install both pieces. And because the regulations don’t require the pieces, Boeing skipped purchasing them. GettyImages-Boeing 737 Rollout The Boeing logo on the first Boeing 737 MAX 9 airplane is pictured during its rollout for media at the Boeing factory in Renton, Washington on March 7, 2017. Federal agencies in the United States are reportedly probing the processes involving the development and approval of Boeing 737 MAX 8 jetliner. Photo: JASON REDMOND/AFP/Getty Images

The angle of attack indicator is what determines how much the plane’s nose is tilted. The angle of attack disagree light activates if the plane's sensor contradicts the indicator.

In the wake of the crashes, Boeing will make the disagree light standard on all new planes, while the indicator will remain optional.

Dennis A. Muilenburg, the CEO of Boeing, issued a statement on Sunday talking about making the new 737 Max planes safer. He said, “As part of our standard practice following any accident, we examine our aircraft design and operation, and when appropriate, institute product updates to further improve safety.”

While some experts have speculated that these missing parts contributed to the crashes, the primary causes of the accidents are still unknown.