One of the most important aspects of flight planning is  obtaining reliable weather information. Fortunately, pilots  have several outlets to receive reliable weather reports and  forecasts to help them determine if a proposed flight can  be completed safely. For visual flight rules (VFR) flights,  federal regulations require pilots to gather weather reports  and forecasts only if they plan to depart the airport vicinity.  Nevertheless, it is always a good idea to be familiar with  the current and expect weather anytime a flight is planned.  Preflight weather information sources include Automated  Flight Service Stations (AFSS) and National Weather Service  (NWS) telephone briefers, the Direct User Access Terminal  System (DUATS), and the Internet. In addition, a multitude  of commercial venders provide custom services. For complete details regarding available weather services and  products, refer to the current version of the FAA Advisory  Circular (AC) 00-45, Aviation Weather Services, and in the  Pilot’s Handbook of Aeronautical Knowledge, Chapter 12,  Aviation Weather Services. Often times in order to obtain a preflight weather briefing,  certain background information must be given to the weather  specialist: type of flight planned, whether flying VFR (Visual  Flight Rules) or IFR (Instrument Flight Rules), aircraft  registration or pilot’s name, aircraft type, departure airport,  route of flight, destination, flight altitude(s), estimated time  of departure (ETD), and estimated time en route (ETE).  Operators of airports, gliderports, or fixed-base operators  (FBO) may obtain current reports and forecasts from the  AFSS or NWS at various times throughout the day and post  them on a bulletin board for easy reference. Weather briefers do not actually predict the weather; they  simply translate and interpret weather reports and forecasts  within the vicinity of the airport, route of flight, or the  destination airport if the flight is a cross-country. A pilot may  request one of four types of briefings: standard, abbreviated,  soaring  [Figure 9-33],  or outlook.  Weather-related information can be found on the Internet,  including sites directed toward aviation. These sites can be  found using a variety of Internet search engines. It is important  to verify the timeliness and source of the weather information  provided by the Internet sites to ensure the information is up  to date and accurate. Pilots should exercise caution when  accessing weather information on the Internet, especially  if the information cannot be verified. Other sources of  accurate weather information are the NWS website located at Weather-ReIated Information  Preflight Weather Briefing Obtaining Weather Information Convergence line Convergence line A B Figure 9-30.  Convergence induced by flow around topography. Drier winds Moist valley breeze Figure 9-31.  Mountain-top convergence. Slow Lift North Figure 9-32.  Convergence induced by flow around topography. 9-21