The federal aviation regulations, specifically 14 CFR 91.205, detail the equipment needed for different flight conditions, such as day VFR, night VFR, IFR, etc. For those of us who earned our ratings a decade ago or earlier, this meant compliance for IFR flight with FAR 91.205(d), which formerly required “two-way radio communications systems and navigational equipment appropriate to the ground facilities to be used.” Except for those few intrepid souls still churning through the clag on an ADF, this language meant that one or more VORs were necessary and that, in turn, triggered the 14 CFR 91.171 requirement for a logged VOR operational check within the preceding 30 days.
In 2007, the FAA recognized that GPS navigation had become reliable and, for many operators, the primary navigation aid. In recognition of this, 14 CFR 91.205 was changed to state the minimum equipment requirement as: “Two-way radio communications systems and navigational equipment suitable for the route to be flown.” So, does this change mean that 30-day VOR checks are obsolete, dead letters for GPS-equipped aircraft? The answer is obviously no for the pilot flying IFR solely (from a legal perspective) in reliance on the VORs. It’s also a solid no for that significant portion of the general aviation fleet with first-generation, non-WAAS GPS units certified under TSO-c129. These “129” GPS units were never certified as a sole means of navigation and required certified equipment—VORs and DMEs—as the primary source of navigational guidance. Some of these “129” units (such as the non-WAAS Garmin 430) contain a certified VOR and ILS and, when that functionality is used for IFR flight, they must be checked operationally and the results logged under 14 CFR 91.171 just like any other VOR receiver.
However, operational checks and logging are probably also not a dead letter even for the pilot with the newest state-of-the-art WAAS GPS.
Current-generation WAAS-enabled GPS units are certified under TSO-c146 and, as such, are approved as a sole means of navigation. However, that sole means of navigation refers to navigating with GPS. These “146” units, like the first generation TSO-c129 predecessors, also may contain integrated VOR and ILS receivers that rely just as much on the same ground station equipment as a standalone VOR and ILS. If this VOR capability is used as the primary guidance on an IFR flight, then the same 14 CFR 91.171 operational check and logging requirements apply. In the real world, GPS can and does fail because of various factors ranging from unintentional radio interference to intentional military test jamming which, in the western states' military operations areas, is not infrequent. When the GPS RAIM warning light appears, the pilot is flying on VORs and 14 CFR 91.171 applies.
Under a 2012 addition to 14 CFR Part 43, database updating is no longer considered maintenance and as such it need not be logged. However, this is not a new age “kick the tires, light the fires, stick in a data card, and fly” freedom. The new 14 CFR 43.3(k) is very specific on strictly following the manufacturer’s procedures, including a function test.
Mark is an attorney in Ventura County, California and is licensed to practice law in California, New York, Hawaii, Michigan and North Carolina. He’s a retired US Navy Captain, Judge Advocate General’s Corps and 40+ year member of AOPA. Mark flies a Twin Comanche and is the father of (and first instructor of) two airline pilots, an aircraft mechanic and a Boeing engineer.