SU1492 crash, the first elements of the investigation

On Sunday, May 5, 2019, images of a plane landing in fire in Moscow are seen all over the world. The aircraft is an SSJ100 owned by the Russian airline Aeroflot. Later, the media will report a death toll of 41. Thanks to several elements revealed, including ADS-B data, the causes of this crash seem to be becoming clearer.

The SU1492 crash 

Warning: This article is not an official report of the SU1492 crash. At the time of writing, the investigation conducted by the Interstate Aviation Committee in Russia is ongoing and will provide the causes of the accident. This article must therefore be seen as an inventory of the various avenues of research and reflection of the investigation.


The aircraft and the airline

The aircraft involved in the accident was a Soukhoï Superjet 100 registered RA-89098. It was delivered in 2017. Built by Sukhoi, it combines many technologies from several suppliers: the PowerJet SaM146 reactors developed jointly by the French engine manufacturer Snecma and the Russian engine manufacturer NPO Saturn or avionics by Thales Avionics. The accident aircraft was maintained in April 2019 before being returned to service.

SSJ 100 aircraft involved in the accident  (©JetPhotos)

The first data analyzed

ADS-B (Automatic dependent surveillance-broadcast) is an air traffic control system. It allows to know different information about a flight. The FlightRadar24 website revealed the data of flight SU1492. Three information are highlighted: in red the altitude, in yellow the speed and in green the vertical speed.
SU1492 ads-b
First ADS-B data (source:FlightRadar24)



The plane line-up on the runway for takeoff and at 15:02:38 the SSJ100 takes off on the runway 25R from Moscow Sheremetyevo Airport. At 15:03, the plane takes off.)

SU1492 data take off
The aircraft accelerates 25R (source:FlightRadar24)


The aircraft takes off (source: FlightRadar24)


At 15:08:35, the aircraft reached 10,000 feet. Only 1 minute later, the aircraft was hit by lightning. The crew changed the transponder code, the communication system with air traffic control, "squawk", first reporting a radio problem at 15:09:27 UTC (18:09 local time) with code 7600.

The aircraft reached 10,575 feet before beginning a gradual descent.

However, the approach was cancelled at 15:16 UTC because the aircraft was flying too high and too fast in the direction of the runway, at 3,150 feet (960 metres) for about 240 knots. Less than 10 minutes later, after completing a loop, the aircraft appeared again but at an altitude of 2600 feet for 130 knots this time.

The crew sent a new message at 15:26:24, signaling an emergency, displaying 7700 with the transponder.

Squawk 7700 (source:FlightRadar24)

A few moments later, the aircraft hit the ground violently before bouncing back. Another impact caused the landing gear to break. The entire aircraft with its engines is in direct contact with the ground causing fire at the tanks.






Altitude during the flight SU1492(source:FlightRadar24)

The landing data SU1492 (source:FlightRadar24)




Flight SU 1492 (source:FlightRadar24)

The speed during landing

The ADS-B data seem to show that the aircraft is approaching the runway at a speed of about 150 knots. It increases in the last few seconds before touchdown, from 141 to 164 knots for a moment. At 18:29:53, the speed reaches 162 knots for an altitude of 650 feet (198 meters).

Aircraft data last minutes (source:FlightRadar24)

Position of the aircraft (blue line)
The speed data can be confirmed by a video taken on board, when calculating the time it takes the aircraft to fly 2 points on the ground. The approximately 650 metres between the Sheremetyevskoye shosse road and the beginning of the runway are covered in about 8 to 9 seconds. This corresponds to a speed of more than 150 knots (more than 277 km/h).


The vertical speed indicates that the aircraft is descending at a rate of more than 700 feet per minute. Investigators will have to determine if there was overspeed, depending on other factors such as aircraft weight, wind, flap settings, etc.


From 15:30 onwards, the ADS-B signal becomes bad (below 600 feet). At 15:31:10 UTC (18:31 local time), the recording ends. The aircraft is located at 650 feet. For precision, Sheremetyevo airport is located at about 190 meters above sea level. In addition, this level is not uniform at the airport.
Last ADS-B data Su1492
Last data SU1492

Any piloting errors?

 "The first mistake of the pilots was to take off in front of the storm. Then, when the situation was complicated but far from catastrophic, they landed instead of burning the kerosene," explains the daily Kommersant, citing a source close to the investigation. The second error could be an excessively high approach speed.

Extracts from radio communications

The captain Evdokimov contacted air traffic control in emergency.
« Pan-Pan, Pan-Pan, Pan-Pan! Work nest. Aeroflot 1492. Moscow approach. Moscow approach. Asking for return. 1492, the loss of radio communications and the aircraft burns in a lightning, »

Control tower: Aeroflot 1492. UIS. Descend 8080 (eight zero eight zero)
... Captain: 900 to the right 140. Aeroflot 1492

18:16, control tower: Aeroflot 1492. Course correct 160. Will any help be needed?
Pilot: Right 160. No, everything is fine. Regularly. Aeroflot 1492.
Control tower: Only communication problems, did you receive well?
Pilot: communication system failure and loss of autopilot control.
Control tower: Received.

The sentence "The plane burns in lightning" pronounced by the captain seems very surprising, and raises many questions: was the plane really on fire, did the crew make a mistake in analysis or is it a clumsiness?



The lightning strike designated as responsible for the accident?

Indeed, passengers on the aircraft and the captain himself reported that the aircraft was struck by lightning. Weather conditions were deteriorated around Sheremetyevo Airport. Although lightning alone cannot completely damage an aircraft, it can interfere with radio communications, electronics and electrical systems. The loss of power on board makes it impossible to activate the flaps to slow the aircraft and all the systems that protect the aircraft and allow pilots to better steer it.

Finally, the flight instruments could have been affected by the incident. It would have become difficult to know exactly the speed and altitude of the aircraft

As soon as the plane lands, help is contacted. The transcript of the exchanges is available in Russian here. The firefighters noticed the fire and tried to determine the number of victims. The first rescue vehicle arrived on scene at 18: 32, two minutes after the aircraft landed.

According to the latest toll, 41 people out of 78 on board died, including several crew members and children. In addition, the United States has confirmed the presence of one of its citizens on the list of victims


Factors that appear to have made the situation worse

First, the loss of ground contact did not allow the emergency services to be engaged before landing. Thus, rescuers arrived after the aircraft came to a complete stop. The evacuation also seems to have contributed to the heavy toll. According to a source from the Interfax news agency, "an eyewitness investigation suggests that when the plane hit the ground and caught fire, some passengers began to remove their personal belongings from the luggage racks in a panic. This made it difficult to evacuate people from the last rows of the aircraft, and they died in the fire. Indeed, images seem to confirm this information. In addition, the aircraft was serving Murmansk, a city located 1447 km from Moscow as the crow flies. The tanks were full, only half an hour after takeoff.

Passengers holding baggages 

Concerning the weather conditions, there was a wind on the ground. Control tower: Aeroflot 1492, 160 degree ground wind, 7 gusts of 10 metres per second, VP24 on the left, I authorize landing.

Finally, the evacuation of the aircraft was difficult because of the high flames. Two slides located at the front of the aircraft allowed the evacuation. However, one crew member tried to evacuate the aircraft from the rear, but was unsuccessful. His death was later confirmed.

 Consequences

 No suspension of SSJ100 flights was taken after the crash. "A criminal investigation for breach of security rules" has been opened, said in a statement the Russian Investigation Committee, which is responsible for investigating such cases. The Interstate Aviation Committee IAC, (the equivalent of the NTSB) analysing the black boxes the day after the crash.
See all ADS-B data


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