Sunday, January 10, 2021

Sriwijaya Air flight SJ182

Sriwijaya Air flight SJ182 crashed shortly after take off from Jakarta on 9 January 2021. The flight, operated by 737-500 registered PK-CLC, departed at 07:36 UTC (14:36 local time). The last ADS-B signal from the aircraft was received by Flightradar24 at 07:40 UTC (

(airplane attitude not representative as shown)

The airplane appears to be destroyed on impact with all 62 lives lost. 

Sorrow for the victims and for those that loved them.

Sunday, January 3, 2021

Mid-Value Select (MVS): Goldilocks in the House of MCAS

Angle of Attack (AoA) is measured on the 737MAX using two AoA vanes, one installed on the left side of the airplane and the other on the right side. While each AoA vane is calibrated and precise, inferring AoA directly overlooks local aerodynamic factors that can cause the sensor reading to diverge from the desired value, notably with sideslip. A tolerance exists from what the AoA vane senses and the expected value. The question arises, how to manage AoA sensor tolerances or undesired behavior to maximize availability of desired functionality, while limiting exposure to undesired hazards?