What happened to the Russian plane that crashed outside Moscow on February 11? Here are the leading theories

Almost immediately after taking off from Moscow’s Domodedovo airport on the afternoon of Sunday, February 11, an An-148 operated by “Saratov Airlines” crashed, killing all 65 passengers and six crew members. Rescue workers have located both of the plane’s black boxes, and sources in the crash investigation, as well as aviation experts, are still entertaining widely varying theories to explain the tragedy.

One of the leading theories is that the plane suffered a mid-air explosion, due perhaps to a terrorist attack or malfunction that may have damaged an engine. Sources speaking to the newspaper Kommersant have recalled the only other crash involving an An-148: in 2011, when a training flight crew went down after exceeding the aircraft’s maximum speed, after the sensors relayed inaccurate data. In that incident, all six crew members died. The same sources told Kommersant that the “Saratov Airlines” plane that crashed on Sunday was flagged for two safety violations in 2017: the aircraft’s engine oil had been replaced half as often as necessary. Evidence that seems to support the mid-air explosion theory includes the fact that the plane’s wreckage covers a 30-hectare (74-acre) area.

The data retrieved by first responders reportedly indicates that a mid-air explosion is unlikely. Sources told the magazine RBC that the aircraft’s engines operated right until the moment of impact with the ground. The exact source of this information is unclear, but the plane’s black boxes should contain data on the aircraft’s entire system operations. Officials have also largely dismissed the possibility that the crash was caused by a terrorist attack, given that emergency workers have not discovered any traces of a bomb. The wide wreckage area could be due to the fact that the plane crashed just after takeoff, with a full fuel tank, which caused a major explosion upon impact with the ground. A large blast is visible at the moment of impact in at least one video recorded by an outdoor surveillance camera near the crash site.

Whatever happened, the plane fell so quickly that the pilots didn't have time to report it to air traffic control. The An-148 was only in the air for a few minutes: the crew received permission to climb to cruising altitude, and afterwards they simply stopped responding. Early reports that the pilots requested an emergency landing in Zhukovsky were unconfirmed. Flight tracking data shows that the plane's altitude (the blue curve in the image below) gradually increased, briefly dipped, and then leveled off, before suddenly plummeting.

For unknown reasons, Captain Valery Gubanov declined to have the plane de-iced. The An-148 has a special heating system for its hull, however, and pilots point out that the aircraft would not have been able to reach an altitude of two kilometers (6,500 feet), if icing had caused the crash. Nevertheless, Russia’s Investigative Committee says it’s treating bad weather conditions as one of the potential explanations for the incident.

Experts have completely refuted an early rumor that the An-148 may have collided with a helicopter operated by the Russian Postal Service. The news agency Interfax attributed the information to an unnamed source, but Russia’s Federal Emergency Management Agency and the Russian Postal Service later clarified that the An-148 was merely carrying a bag that contained advertising leaflets bearing the Postal Service’s logo.

Whatever caused the crash, production of the An-148 is now in question. A factory in Voronezh is currently finishing the assembly of two more, but there are no new orders after that. “Saratov Airlines” has another four An-148s, and there are six in the “Rossiya” Special Flight Detachment. Currently, these aircraft are still permitted to fly in Russia’s skies, though “Saratov Airlines” has voluntarily suspended all its An-148 flights, pending a review of the aircraft’s safety.