When their weather radar failed; a B767-300 flight crew declared an emergency; returned to their departure airport and landed uneventfully overweight rather than dump fuel. Difficulty accessing necessary information and procedures in their newly published Aircraft Operating Manual--developed as a result of the merger of two large pilot groups--was cited as a complicating distraction.

Narrative

While in cruise flight the 'WX FAIL' light came on and off several times on both pilots' instrument panels. We accomplished the weather radar failure procedure in the new Aircraft Operating Manual (AOM) but were not able to resolve our problem. I contacted Maintenance Control and they asked us to reset the weather radar circuit breaker. I refused; due to the fact that the procedure in the Flight Manual (FM) did not direct us to reset the breaker. After several minutes of research; Maintenance Control directed us to an AOM page that lists circuit breakers which may be recycled in flight in order to restore a system. We recycled the directed circuit breaker but radar continued in a failed mode. We then agreed to return to our departure airport and make an overweight landing. I instructed the flight attendants to cease the service and informed them of our return; explaining that it would be a normal landing and no cabin preparation would be required. I made a PA to the passengers explaining the reason for our return. Finally; we declared an emergency; performed an uneventful flaps 30 landing using a Vref speed of 162 KTS on the airport's longest runway; using auto brakes 3 and heavy reversing during the landing roll. CFR inspected our tires after landing. One wheel on the right main reached a temperature of 5 units. All other tires were in the normal range. The firemen brought out a couple of fans to cool down the tire. We were towed to the gate by a company tug. Finding the right stuff in the new AOM is a MAJOR PROBLEM. It needs to have a better index system.