As a first guess I would say...
a. Accidental chute deployment by the gaffer driving.
b. Deliberate chute deployment by the gaffer driving just to show off.
c. Mechanical/electrical fault deploys chute, gaffer driving does a sterling bit of work up front, notices a bit of excess drag and does the necessary, good job done, free drinks in the bar.
Apart from that, absolutely no idea. Not even seen a Typhoon yet.
