Boeing’s newest 737 airplane has been grounded in China, Indonesia, and Ethiopia after an Ethiopian Airlines crash killed 157 people on Sunday. It’s the second deadly crash involving a Boeing 737 Max 8 in the past five months; in October, a 737 Max 8 operated by budget airline Lion Air crashed shortly after takeoff, killing 189 people.

Sunday’s crash took place just after takeoff as well, prompting worries that the two Max 8 failures could be related. Officials haven’t linked the two crashes yet, and investigators from the Federal Aviation Administration and the National Transportation Safety Board are expecting to learn more after recovering the flight data recorder and the cockpit voice recorder from the Ethiopian Airlines crash.

automated anti-stall software in the Max model may have been erroneously activated by incorrect flight data

Indonesian and American aviation authorities have raised the possibility that Lion Air Flight 610’s crash was because of pilots fighting an automated anti-stall software in the Max model that may have been erroneously activated by incorrect flight data, according to The New York Times.

Other operators could also ground flights that are scheduled to use Boeing’s 737 airplanes. On Sunday, Cayman Airways said it would discontinue the use of its two 737 aircraft in response to the crash.

In the wake of the tragic loss of Ethiopian Airlines Flight 302 on March 10, 2019, which was being operated by a Boeing 737 Max 8 aircraft, Cayman Airways extends its condolences to the families and loved ones of the... https://t.co/jEOZryjxIi — Cayman Airways (@CaymanAirways) March 11, 2019

After the Lion Air crash, Boeing has discussed updating the software in its 737 Max planes. The flight that crashed on Sunday was the first of the day for the plane; the experienced crew told controllers they were having technical problems with the plane shortly before the crash.

Boeing issued a statement expressing condolences for the lives lost in both crashes, and it said it would be delaying the scheduled unveiling of its new 777X jetliner. Boeing announced last week that the 777X, which can carry as many as 425 passengers, would make its debut this coming Wednesday. It described it as “the largest, most efficient twin-engine jet” on the planet.

“we do not have any basis to issue new guidance to operators.”

In an email to The Verge, a spokesperson for the Chicago-based company reiterated that “safety is our number one priority,” but they noted that Boeing will not issue any guidance related to the 737 Max 8 airplanes.

“We have engaged our customers and regulators on concerns they may have — and would refer you to them to discuss their operations and decisions,” Boeing spokesperson Paul R. Bergman said. “Safety is our number one priority and we are taking every measure to fully understand all aspects of this accident, working closely with the investigating team and all regulatory authorities involved. The investigation is in its early stages, but at this point, based on the information available, we do not have any basis to issue new guidance to operators.”

Updated Statement on Ethiopian Airlines Flight 302: https://t.co/0jyiFuGHIE pic.twitter.com/Unl92SYykI — Boeing Airplanes (@BoeingAirplanes) March 10, 2019

Before the crashes, Boeing was bullish about its new 737 Max series. By mid-2018, the company had increased production to 52 airplanes per month in order to meet increased demand. The 737 Max family also achieved a sales milestone in December, surpassing 5,000 net orders with 181 new sales in December, Boeing said.

Boeing was marketing its 737 Max airplanes as more fuel efficient than standard twin-engine jets. Improvements in hardware and software were meant to reduce fuel use and CO2 emissions by “at least 14 percent compared to today’s Next-Generation 737s – and by 20 percent more than the single-aisle airplanes they replace,” the company said recently.