[RWGinger]

It was not someone in the cockpit that reported smoke. It was sensors that automatically reported smoke
and a breach of cockpit window

[Madame Dufarge]

I wonder whether the breach of the cockpit window could have have been a bullet hole.

[BenLurkin]

smoke and a breach of cockpit window

Leads me to float a wild theory: Guy in left seat shot guy in right seat thereby creating smoke. Bullet(s) passed through target and breached window.