Metrojet 9268 Extended Mode-S Data Decoded - 03/11/15 - FR24
In addition to our initial data, we have decoded Extended Mode-S data from a single receiver with the best reception in the area of Metrojet flight 9268. This is additional data sent from the aircraft when requested by air traffic control. This data is raw data from the aircraft that has been decoded, but not processed, by Flightradar24. Our previously released data set was synthesized data from multiple receivers processed normally through Flightradar24 servers and did not include Extended Mode-S data.
Upon request, we have supplied this data to the French Bureau d’Enquêtes et d’Analyses (BEA) as well as the Egyptian investigative authorities.
Important Notes About Data Validity
We supply this data set with important notes about the validity of certain data within the set.
At this point, from 04:13:13.872 to 04:13:30.653 we consider the altitude values to be unreliable. The altitude value is derived via a pressure sensor, which can be affected by changes in pressure outside the aircraft. In this case, what we’re learning about the state of the airframe calls into question the validity of the altitude readings during this time period. From 04:13:31.143 until our last received signal from the aircraft at 04:13:39.384 we received GPS altitude data from the aircraft. While GPS altitude data is not itself unusual, our receipt of it from this flight is. In normal cases, GPS altitude data must be requested from Air Traffic Control, but in this instance, we only see it in the data set after the flight has experienced a significant event and begun to descend rapidly.
Similarly, True Airspeed (TAS) is a pressure-derived value and may be unreliable after 04:13:13.872.
In this data set, Vertical Speed (Vspeed) is provided from the aircraft via GPS data, not pressure data. Our initial data set provided Vspeed values derived from pressure data, which, like altitude and TAS, we consider unreliable after 04:13:13.872.