"I've heard a pilot is legally required to obtain a weather briefing before all flights. Does this mean a call to a Flight Service Station for a briefing? Also, if I do call FSS and talk to a briefer, should I still review online weather sources?" - Jan P.
“According to the NTSB, the simple answer is NO (you aren’t legally required to call the FSS). The NTSB states…
Part 91 regulations do not specifically require the use of any particular sources of weather information for GA pilots, but do require that all pilots familiarize themselves with weather and weather forecast information before beginning a flight.
Certainly making a phone call to speak with a FSS briefer isn’t a bad idea, but can fall short of the information a pilot needs to make a go or stay decision when the weather is marginal or more complex. Many flights can be easily taken even though FSS gives you a lot of doom and gloom, and some flights should not be taken even when FSS says that it shouldn’t be a problem.
Convective icing during the warm season is a perfect example. Flying IFR through a field of congested cumulus clouds at temperatures below 0°C will produce moderate or greater airframe ice and potentially moderate or greater turbulence while in those clouds. However, if this area of convection does not meet convective SIGMET criteria, the Aviation Weather Center will not issue AIRMETs since these enroute advisories are for non-convective icing and non-convective turbulence. It is likely that FSS will not point out this threat during a standard briefing.”