NEW: Boeing CEO to step down by end of year amid safety concerns

Boeing has announced that CEO David Calhoun will be leaving the company by the end of the year.

The move comes following a number of serious malfunctions on planes manufactured by the airline giant.

In a letter to employees on Monday, Calhoun said the Alaska Airlines Flight 1282 incident, during which a panel blew off the plane in mid-air, was a "watershed moment" for the company.

"We must continue to respond to this accident with humility and complete transparency," he wrote. "We also must inculcate a total commitment to safety and quality at every level of our company. The eyes of the world are on us, and I know we will come through this moment a better company, building on all the learnings we accumulated as we worked together to rebuild Boeing over the last number of years."

"We are going to fix what isn't working, and we are going to get our company back on the track towards recovery and stability," he added.

The 737 involved in the aforementioned incident appeated to have had bolts missing, per an investigation conducted by the National Transportation Safety Board.

"Overall, the observed damage patterns and absence of contact damage or deformation around holes associated with the vertical movement arrestor bolts and upper guide track bolts in the upper guide fittings, hinge fittings, and recovered aft lower hinge guide fitting indicate that the four bolts that prevent upward movement of the MED plug were missing before the MED [mid exit door] plug moved upward off the stop pads," the report stated.

Even before the results were made public, however, Calhoun released a statement announcing that Boeing accepted full accountability for what happened.

The soon-to-be former chief executive also revealed in his letter to staff that former Qualcomm CEO Steve Mollenkopf has been brought in to chair the board and will facilitate the search for Calhoun's replacement. 

Stan Deal, the CEO of Boeing's Commercial Airplanes division, is also retiring, and will be replaced by the company's current COO, Stephanie Pope.

This is a developing story. Check back for updates.