Its funny, understanding of what is actually going on at an incident scene is exceptionally important for the responders, in that, not every scene is an immediate "surround and drown" upon arrival. Sometimes a little analysis of what's going on before flipping switches and going immediate full-firefighting ops, is important. Case in point, rolling up once on an engine fire report. There's fire present, but its pretty apparent it's a core/tailpipe fire (airplane not answering calls on freq.....figure they're busy enough as is), and that the crew is motoring the engine in accordance with their procedures to flush the residual fuel out in order to snuff out the flames. The newbie firefighter onboard has the narrow focus of "fire....must put out now", rather than give it a minute, lets hang on a second and monitor what's going on.....that fire isn't going anywhere. Only if the swirling flames start to slow down their swirling, indicating that the motoring isn't working and has been terminated by the crew as they shut down, or the T-handle has been finally pulled and the motoring automatically terminated for the same reason;
now we can go in and snuff it out from the ass end of the engine. Until that time, and with fire not actually spreading anywhere, no need to fill the engine with water/foam
just yet and potentially causing damage where there didn't need to be.
After that time of motoring being unsuccessful and the crew terminating it, now the water/foam will now do less damage to the engine, than the core of the motor far exceeding its max temps and melting.
