 Air traffic controllers have different responsibilities to aircraft operating under the different sets of rules.While IFR flights are under positive control, in the US and Canada VFR pilots can request flight following, which provides traffic advisory services on a time permitting basis and may also provide assistance in avoiding areas of weather and flight restrictions, as well as allowing pilots into the ATC system prior to the need to a clearance into certain airspace.Across Europe, pilots may request for a "Flight Information Service", which is similar to flight following.