There are three leading theories regarding the loss of Metrojet 9268 on Oct. 31, 2015: 1) a missile fired from the ground, 2) mechanical malfunction which resulted in catastrophic damage, and 3) an explosion from inside the aircraft.

To recap the tragic flight, Metrojet 9268 took off from Sharm el-Sheikh International Airport headed for St. Petersburg at 5:51am local time (03:51UTC). At 6:14am, 23 minutes later, the aircraft disappeared from radar screens.

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An analysis of the flight parameters shows that at 04:12:58 UTC, just after passing 31,000 feet, the vertical speed changes from the steady climb of just under 600fpm to a negative 320 fpm in the next second.

A study of the ADS-B data from Flightradar24.com surrounding the time of the incident informs the likelihood of each theory.

UTC Time FlightID Latitude Longitude Altitude (Ft) Ground Speed (Kts) Heading Vertical Speed Autopilot Target Altitude (ft)
04:12:53 KGL9268 30.143 34.182 30875 407 335 512 32000
04:12:56 KGL9268 30.143 34.182 30875 407 335 512 32000
04:12:56 KGL9268 30.146 34.18 30675 408 336 576 32000
04:12:57 KGL9268 30.148 34.179 30750 408 336 576 32000
04:12:58 KGL9268 30.149 34.179 31100 408 335 -320 32000
04:13:00 KGL9268 30.151 34.178 33500 404 335 -3584 32000
04:13:00 KGL9268 30.153 34.177 30975 398 333 -5760 32000
04:13:00 KGL9268 30.153 34.177 30975 398 333 -5760 32000
04:13:00 KGL9268 30.154 34.176 29750 347 333 8000 32000
04:13:02 KGL9268 30.156 34.175 33275 342 335 -3904 32000
04:13:03 KGL9268 30.157 34.174 30650 296 332 -5696 32000
04:13:08 KGL9268 30.161 34.173 30825 246 351 4544 32000
04:13:11 KGL9268 30.177 34.162 29925 306 325 -6080 32000
04:13:11 KGL9268 30.177 34.162 29925 306 325 -6080 32000

The data conflicts for a few seconds showing the plane’s altitude increasing as the rate of descent accelerates. This momentary aberration may have been caused by the violent forces the sensors were experiencing. Two seconds later the plane begins falling at a rate between 4000 and 8000 fpm. The ground speed decreases at a rate consistent with a ballistic trajectory as the flight path of the debris curves towards the ground until 04:13:12, 14 seconds after the initial anomaly, the horizontal speed becomes minimal and the vertical rate of descent stabilizes. 10 seconds later the data transmission was discontinued.

Of the three theories, the first, a missile fired from the ground by ISIS, can be reasonably discounted. The aircraft broke up nearing its cruise altitude of 32,000 feet. Shoulder-launched MANPADS are only a threat to targets below 20,000 feet. A much more sophisticated Surface to Air missile system, including search and fire-control radars, as well as the missile battery itself, would be required to bring a target down at that altitude. ISIS is not known to be in possession of such a system.

The second theory of a mechanical or structural failure resulting in catastrophic damage is certainly plausible. There were initial reports from the First Officer’s wife on Russian TV where she stated he had complained about the general condition of the plane. She quoted him saying “The technical condition of the aircraft left much to be desired.” This is an open ended statement that leaves a wide swath subject to interpretation. The conditions he spoke of may have ranged from an inoperable lavatory to a critical component of the aircraft that the pilots were working around in order to complete the mission.