NOTE-
Any suitable airport can be used to land in the event of a VOR outage. For example, an airport with a DME-required ILS
approach may be available and could be used by aircraft that are equipped with DME. The intent of the MON airport is to
provide an approach that can be used by aircraft without ADF or DME when radar may not be available.

2. Navigating to an airport. The VOR MON will retain sufficient VORs and increase VOR service volume
to ensure that pilots will have nearly continuous signal reception of a VOR when flying at 5,000 feet AGL. A
key concept of the MON is to ensure that an aircraft will always be within 100 NM of an airport with an instrument
approach that is not dependent on GPS. (See paragraph 1-1-8.) If the pilot encounters a GPS outage, the pilot
will be able to proceed via VOR-to-VOR navigation at 5,000 feet AGL through the GPS outage area or to a safe
landing at a MON airport or another suitable airport, as appropriate. Nearly all VORs inside of the WUSMA and
outside the CONUS are being retained. In these areas, pilots use the existing (Victor and Jet) route structure and
VORs to proceed through a GPS outage or to a landing.
3. Using the VOR MON.
(a) In the case of a planned GPS outage (for example, one that is in a published NOTAM), pilots may
plan to fly through the outage using the MON as appropriate and as cleared by ATC. Similarly, aircraft not
equipped with GPS may plan to fly and land using the MON, as appropriate and as cleared by ATC.
NOTE-
In many cases, flying using the MON may involve a more circuitous route than flying GPS-enabled RNAV.

(b) In the case of an unscheduled GPS outage, pilots and ATC will need to coordinate the best outcome
for all aircraft. It is possible that a GPS outage could be disruptive, causing high workload and demand for ATC
service. Generally, the VOR MON concept will enable pilots to navigate through the GPS outage or land at a
MON airport or at another airport that may have an appropriate approach or may be in visual conditions.
(1) The VOR MON is a reversionary service provided by the FAA for use by aircraft that are unable
to continue RNAV during a GPS disruption. The FAA has not mandated that preflight or inflight planning include
provisions for GPS- or WAAS-equipped aircraft to carry sufficient fuel to proceed to a MON airport in case of
an unforeseen GPS outage. Specifically, flying to a MON airport as a filed alternate will not be explicitly
required. Of course, consideration for the possibility of a GPS outage is prudent during flight planning as is
maintaining proficiency with VOR navigation.
(2) Also, in case of a GPS outage, pilots may coordinate with ATC and elect to continue through the
outage or land. The VOR MON is designed to ensure that an aircraft is within 100 NM of an airport, but pilots
may decide to proceed to any appropriate airport where a landing can be made. WAAS users flying under Part
91 are not required to carry VOR avionics. These users do not have the ability or requirement to use the VOR
MON. Prudent flight planning, by these WAAS-only aircraft, should consider the possibility of a GPS outage.
NOTE-
The FAA recognizes that non-GPS-based approaches will be reduced when VORs are eliminated, and that most airports
with an instrument approach may only have GPS- or WAAS-based approaches. Pilots flying GPS- or WAAS-equipped
aircraft that also have VOR/ILS avionics should be diligent to maintain proficiency in VOR and ILS approaches in the event
of a GPS outage.

1-1-4. VOR Receiver Check
a. The FAA VOR test facility (VOT) transmits a test signal which provides users a convenient means to
determine the operational status and accuracy of a VOR receiver while on the ground where a VOT is located.
The airborne use of VOT is permitted; however, its use is strictly limited to those areas/altitudes specifically
authorized in the Chart Supplement U.S. or appropriate supplement.
b. To use the VOT service, tune in the VOT frequency on your VOR receiver. With the Course Deviation
Indicator (CDI) centered, the omni-bearing selector should read 0 degrees with the to/from indication showing
"from" or the omni-bearing selector should read 180 degrees with the to/from indication showing "to." Should
the VOR receiver operate an RMI (Radio Magnetic Indicator), it will indicate 180 degrees on any omni-bearing

Navigation Aids

1-1-3