The derrick sees the ladder set up on an angle with the guide ropes holdig it in place. At the top is a pulley system for raising and lowering a stretcher or rescuer (in place of a tripod or other device).
I was always taugtht that if you strained an aluminium ladder that way, that they'd fold in half from the stresses. Never found anyone willing to let me try it to find out!!!!
I learned ladder derricks with aluminum ladders in 1975.
This is a commonly-taught Rapid Intervention rescue technique in some parts of the U.S.as well, although in a simpler form that requires fewer firefighters than your photo.
"Thirteen fire departments in the United States use wooden ladders, 12 of them in California. They are:
-- San Francisco -- Oakland -- Hayward -- Alameda County -- San Mateo -- Los Angeles -- Los Angeles County -- Glendale (Los Angeles County) -- Pasadena -- West Covina (Los Angeles County) -- Montebello (Los Angeles County)
-- Arcadia (Los Angeles County) -- Bellevue, Washington"
Our fire academy used to teach this technique (an angled "ladder gin") as part of the basic low-angle rescue course, but with only two guy ropes. It was taught exclusively with 24-foot aluminum extension ladders, but with the fly section not raised so the ladder strength was doubled.
We learned the church raise with a 50-foot bangor ladder at MFRI in 1975. It took 8 firefighters plus an officer to do the raise - two for the ladder, two for the tormentor poles, four on the guy ropes, and the officer directing.
I don't know where the info has come from that we can't do derricks with aluminium- it would appear that it's perhaps one of those war stories that has grown legs and gone from there...
I teach in my safety classes to child care providers and this is something we need to be aware of. When I started in 78 a residentual fire might get up to 700-800 degree now because of the man-mde materials they can get up to 1800 degrees. Thats 3.5 times the temp of your oven.
Theres also heat shock. With elevated heart rates from the excitment and activity and going in a high temp eviroment can and will cause heart attacks which we all know is the leading cause of death in FF's