Date: 201704
Local time of day: 1201-1800
Flight conditions: VMC
Light: Daylight
Aircraft: B787 Dreamliner Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
ATC / advisory: Center ZZZZ
Aircraft component: Weather Radar
Component problem: Design
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Confusion; Training / Qualification
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Result: General None Reported / Taken
Contributing factors: Aircraft; Company Policy; Human Factors
Primary problem: Ambiguous

Narrative: With operation of the Rockwell Collins MultiScan Weather Radar unit installed in the B787 we are continuing to see anomalies that are unexplained. These continuing anomalies are leading many pilots on the 787 to lose faith in the weather radar system. With what is being seen; we are potentially putting our aircraft and passenger's safety in jeopardy.During our flight over the ocean we observed a few of these Weather Radar anomalies that I would hope can explain what is occurring with the system to aid in correcting defective radar hardware/software or lack of training in the use or understanding of the equipment. While in WX+T AUTO there was a strong return at the 3 o'clock position and approximately 40 miles. At approximately 120 miles from the cell we placed a waypoint over it to aid in our ability to watch it as we approached the cell. There was no convective activity in that area which should cause this return. However; it appeared that there was an island located in the area of this strong radar return. The question is; with no convective activity in this area; with the system in WX+T Auto; why would there be such a strong radar return there; even if there was an island in that area? [We also] attempted to intentionally bypass the Ground Clutter Suppression (GCS) feature of the radar and paint a ground return by manually directing the radar tilt to a very low level with the system in MAP mode while over the South ocean. There was no change of display or ground return while in the AUTO position. The use of both AUTO and MAN did not result in any sort of ground return arc where the radar energy first strikes the ground and where the energy last strikes the ground farther from the aircraft. There was no visible indication of any radar return arc at low tilt settings. Why is this? Hours later into the flight while still over the ocean the same tilt and radar settings did result in a typical arc of ground return that would be considered normal. Why do we see two different radar returns (one with no ground return arc and one with a ground return arc) with what appear to be the same operating conditions? Our B787 flight manual has only a dozen pages devoted to the MultiScan radar unit and its features. The Rockwell Collins pilot operator's manual on this equipment is in excess of 220 pages. Granted; that manual is devoted to both Boeing and Airbus installations but contains much more detailed information on the use of the system and is of value to us as pilots. We should have access to this more detailed technical information in some form to help us develop a better understanding of the MultiScan radar features; its value and use of this system.Why is it that we continue to hear NOTHING from the manufacturer; the Fleet; the FAA; the training center or flight operations management regarding this ongoing safety and/or training issue?




Synopsis: B787 Captain reported that the Rockwell Collins MultiScan Weather Radar units continue to produce anomalies that are unexplained. He suggested that either the units are flawed or the flight crews need more training.