[KineticLensman]

> Challenger was destroyed by an FTS system

No. The shuttle broke up when the overall stack became unstable due to the right hand SRB separating because a strut that attached it to the external tank failed (due to a blowtorch effect from a failed O-ring). The Challenger orbiter ended up 'on top' and broke into several chunks - without involvement of any FTS - because of the aerodynamic stress (one of these chunks was the crew compartment). The SRBs were destroyed by their FTS systems, but this was more than 30 seconds after Challenger broke up. The ET simply disintegrated.

[Edit] added emphasis that the orbiter break-up (and destruction) was not due to any FTS.

[dave78]

I'm very aware of why it initially broke up. But once that started, the range safety officer did activate the FTS system.

The point is that rockets carrying crew do indeed have FTS systems - presence of a crew doesn't negate that need.

[ben_w]

The SRBs (and the EFTs) had FTS's, but the Orbiters didn't.

[BobaFloutist]

>the range safety officer did activate the FTS system.

That doesn't sound very automatic.