In this question about aircraft dumping fuel I was told that there may possible be guidance in the QRH. I know that there are a lot of guidelines given to pilots, but I've never heard of this one. Would anyone care to explain, from a pilots perspective, what exactly a QRH is and how it's used in modern aircraft operation?
A QRH is a Quick Reference Handbook and is an approved (by some overseeing entity) document specific to an airplane and operator that contains checklists for just about anything the airplane can experience. At my airline we had copies in the airplane and also in our company flight manual (CFM).
The entry point into a QRH checklist is one of a few things
For option 1, there are various checklists that must be memorized and performed at a moments notice with no reference to the checklist. Some of these are things like trim runaways, engine fire/severe damage, emergency descent. Once the memory part of the checklist is complete you refer to the printed version of the checklist in the QRH to verify and perform additional steps beyond the part you were required to memorize.
For the other options, any time anything abnormal happens or an EICAS message is presented, there are indices by procedure name and also by EICAS message into a specific procedure in the QRH to follow. These procedures may reference other procedures.
For example, If I were to experience a dual engine failure, I would pick up my QRH and find the procedure "DUAL ENGINE FAILURE", this procedure says I should have the master warning light illuminated (and an aural triple chime) and I should see the EICAS message (in red) "ENG 1-2 OUT". After verifying this presentation and verifying I am in the right procedure, I would perform:
A QRH is a Quick Reference Handbook.
It is basically the checklist used in the aircraft along with other useful information, which varies from QRH to QRH, but can include things like system diagrams, maximum cruising altitudes for the current conditions, takeoff and landing performance, etc.
It is usually a small form, spiral bound document that is convenient and easy-to-use in the cockpit: