It may be weeks or months until we know why Ethiopian Airlines Flight 302 crashed minutes after takeoff Sunday, killing all 157 passengers and crew on board — if the cause of the crash is determined at all. Support our journalism. Subscribe today. arrow-right But the crash is drawing comparisons to another air disaster, the Oct. 29 wreck of Lion Air Flight 610, which went down off the coast of Indonesia, killing all 189 people on board.

On Wednesday, President Trump grounded the type of aircraft involved in both crashes — Boeing 737 Max — following the European Union and more than a dozen other nations that took action earlier in the week. The Federal Aviation Administration’s order to ground the planes states that the similarities between the two crashes “warrant further investigation of the possibility of a shared cause for the two incidents that needs to be better understood and addressed.” AD AD Although the Indonesian crash is still under investigation, a preliminary report released in October by local authorities offers details that are strikingly similar to the Ethiopian Airlines flight. Both incidents involved the Boeing 737 Max 8. And there are other parallels: Both aircraft crashed just minutes after takeoff; both struggled to gain altitude; and both appeared to ascend and descend several times before crashing. Both flights crashed within minutes of takeoff Lion Air Flight 610 took off from Jakarta’s Soekarno-Hatta International Airport at 6:20 a.m. Oct. 29 in clear conditions. Just 12 minutes into its journey to Depati Amir Airport in Pangkal Pinang, it crashed into the sea off the coast of Java. AD Ethiopian Airlines Flight 302 left Addis Ababa, Ethiopia, at 8:38 a.m. en route to Nairobi. It lost contact with air traffic control roughly six minutes later, crashing near Bishoftu, less than 40 miles away. Thus far, there is no indication that bad weather was involved. AD [Read the preliminary report on the Lion Air Flight 610 crash in Indonesia] Both flights struggled to gain altitude When Lion Air Flight 610 left Jakarta, it was supposed to reach a cruising altitude of 27,000 feet, according to the preliminary report. But the aircraft struggled to gain altitude, limiting the crew’s room to gain control before the plane plummeted into the ocean at a reported 450 mph. AD Flight 302’s altitude was abnormally low beginning shortly after takeoff from the airport at Addis Ababa, which is more than 7,000 feet above sea level. 15,000 feet above mean sea level Altitude of previous 737 Max ﬂights Last point of recorded flight data 10,000 Flight 302 5,000 0 1 2 3 Minutes after takeoff Source: Flightradar24 Flight 302’s altitude was abnormally low beginning shortly after takeoff from the airport at Addis Ababa, which is more than 7,000 feet above sea level. 15,000 feet above mean sea level Altitude of previous 737 Max ﬂights 10,000 Last point of recorded flight data Flight 302 5,000 0 1 2 3 Minutes after takeoff Source: Flightradar24 Flight 302’s altitude was abnormally low beginning shortly after takeoff from the airport at Addis Ababa, which is more than 7,000 feet above sea level. 15,000 feet above mean sea level Expected altitude based on previous flights 10,000 Last point of recorded flight data Flight 302 5,000 0 1 2 3 Minutes after takeoff Source: Flightradar24 Flight 302’s altitude was abnormally low beginning shortly after takeoff from the airport at Addis Ababa, which is more than 7,000 feet above sea level. 15,000 feet above mean sea level Altitude of previous 737 Max ﬂights 10,000 Last point of recorded flight data Flight 302 5,000 0 1 2 3 Minutes after takeoff Flight 302’s altitude was abnormally low beginning shortly after takeoff from the airport at Addis Ababa, which is more than 7,000 feet above sea level. 15,000 feet above mean sea level Altitude of previous 737 Max ﬂights 10,000 Last point of recorded flight data Flight 302 5,000 0 1 2 3 Minutes after takeoff

Though there has yet to be an investigation into Ethiopian Airlines Flight 302, preliminary data collected by Flightradar24 suggests that the aircraft struggled to climb at a steady speed.

In both cases, pilots alerted air traffic control that there was something wrong and asked to return to the airport. Neither made it back.

Both flights ascended and descended several times before nose-diving

What is most striking about the Lion Air plane’s 12-minute journey is that the plane pitched downward more than two dozen times before its final plunge.

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Though it is not yet clear what happened aboard the Ethiopian Airlines flight, — and there may be no connection between what happened in Indonesia and Ethiopia — the aircraft also appeared to ascend and descend while accelerating, according to preliminary data from Flightradar24.

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In the case of the Indonesian crash, the preliminary report offers some clues as to what caused the nose of the plane to repeatedly dip.

The study found that the Lion Air aircraft’s flight maintenance log showed several problems with the plane each day between Oct. 26 and Oct. 29, including errors involving air speed and altitude information displays.

The preliminary report also found that some of the aircraft’s equipment was checked before its final flight but that the aircraft’s “angle of attack” sensor was not. The angle of attack sensor measures whether the plane is at risk of stalling because its nose is too high for the wings to generate enough lift at a given airspeed.

A key finding was that this sensor was sending erroneous readings throughout the short flight that day, The Washington Post reported.

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As the aircraft made its initial ascent, the sensor insisted that the nose of the plane was too high for the plane’s airspeed, creating the risk of a stall, and an automatic feature kicked in, sending the nose downward as the pilots struggled to force it back up.

“Black-box data released by Indonesian investigators showed that the pilots were pulling back on the control column, attempting to raise the plane’s nose, with almost 100 pounds of pressure before they crashed,” The Post reported.

Although the preliminary report stressed that the investigation was continuing and did not assign blame for what happened, the crash raised questions about whether airlines and pilots had been trained on all the 737 Max’s software features.

The Federal Aviation Administration issued an emergency notice to all airlines that use the aircraft, warning them that faulty sensor inputs “could cause the flight crew to have difficulty controlling the airplane,” leading to “possible impact with terrain.”