14 CFR Part 43, § 43.3(h).  Pilots using the databases are ultimately responsible for  ensuring that the database they are operating with is  current. This includes checking Notices to Airmen (NOTAM)­ type information concerning errors that may be supplied  by the avionics manufacturer or the database supplier. The  database user is responsible for learning how the specific  navigation equipment handles the navigation database.  The manufacturer’s documentation is the pilot’s best source  of information regarding the capabilities and limitations of  a specific database. [Figure 6-30]  Understanding the capabilities and limitations of the  navigation systems installed in an aircraft is one of the  pilot’s biggest concerns for IFR flight. Considering the vast  number of RNAV systems and pilot interfaces available  today, it is critical that pilots and flight crews be familiar  with the manufacturer’s operating manual for each RNAV  system they operate and achieve and retain proficiency  operating those systems in the IFR environment.  Most professional and general aviation pilots are familiar  with the possible human factors issues related to flightdeck  automation. It is particularly important to consider those  issues when using airborne navigation databases. Although  modern avionics can provide precise guidance throughout  all phases of flight, including complex departures and  arrivals, not all systems have the same capabilities.  RNAV equipment installed in some aircraft is limited to  direct route point-to-point navigation. Therefore, it is  very important for pilots to familiarize themselves with  the capabilities of their systems through review of the  manufacturer documentation. Most modern RNAV systems  are contained within an integrated avionics system that  receives input from several different navigation and aircraft  system sensors. These integrated systems provide so much  information that pilots may sometimes fail to recognize  errors in navigation caused by database discrepancies or  misuse. Pilots must constantly ensure that the data they  enter into their avionics is accurate and current. Once  the transition to RNAV is made during a flight, pilots and  flight crews must always be capable and ready to revert to  conventional means of navigation if problems arise.  Some U.S. airports have been closed for up to several years,  with little or no chance that they will ever reopen; yet their  “indefinite” closure status – as opposed to permanent or  UFN closure, or abandonment – causes them to continue  6-14  Figure 6-30. Database rolls.  the approach identifier field for the VOR/DME Runway  34 approach at Eugene Mahlon Sweet Airport (KEUG) in  Eugene, Oregon, as “V34,” different avionics platforms  may display the identifier in any way the manufacturer  deems appropriate. For example, a GPS produced by one  manufacturer might display the approach as “VOR 34,”  whereas another might refer to the approach as “VOR/DME  34,” and an FMS produced by another manufacturer may  refer to it as “VOR34.” [Figure 6-29]  These differences can cause visual inconsistencies between  chart and GPS displays, as well as confusion with approach  clearances and other ATC instructions for pilots unfamiliar  with specific manufacturer’s naming conventions. The  manufacturer determines the capabilities and limitations  of an RNAV system based on the decisions that it makes  regarding that system’s processing of the airborne  navigation database.  Like paper charts, airborne navigation databases are  subject to revision. According to 14 CFR Part 91, § 91.503,  the end user (operator) is ultimately responsible for  ensuring that data meets the quality requirements for its  intended application. Updating data in an aeronautical  database is considered to be maintenance and all Part 91  operators may update databases in accordance with 14  CFR Part 91, § 43.3(g). Parts 121, 125, and 135 operators  must update databases in accordance with their approved  maintenance program. For Part 135 helicopter operators,  this includes maintenance by the pilot in accordance with  Operational Limitations of Airborne Navigation  Databases  Users Role  Closed Indefinitely Airports 