Originally Posted by
Cubdriver
This rule is a pita and it is rarely used. Most pilots kind of hate it, but knowing the history helps a bit. It was an exemption granted originally to Peoples Express to normal FAA weather rules helping them compete with mainline companies who had more expensive weather departments and their own certified WX reports. The mainlines would get to fly when the same Peoples Express flights had to sit around waiting for NWS updates. It was a way to level the playing field a little bit, making conditional remarks being somewhat vague by nature, less restrictive and less confining for those who cannot afford independent WX reports. Richie Lengel's book also has a good explanation.
"Back in the day", there were other methods to use as well, probably used in conjunction with 3585. Things like planned re-dispatch enroute. Also, even though some may not have been able to pay for their own WX departments, they could pay for something like a RAMTAF, etc from a private vendor. My prior company used to do both.
Even with the experience I have with 3585, as soon as I see in on the release the FIRST thing I do is pull out the FOM and read the section. It simply chews up too much of my personal memory space to memorize it. Combine that if it's a 5 am show following an RR overnight, etc.