FIG 1-1-3

Lower Edge of Low and High Service Volumes (in altitude ATH)

2. With the progression of navigation capabilities to Performance Based Navigation (PBN), additional
capabilities for off-route navigation are necessary. For example, the VOR MON (See paragraph 1-1-3 f.)
requires the use of VORs at 5,000 feet AGL, which is beyond the original SSV ranges. Additionally, PBN
procedures using DME require extended ranges. As a result, the FAA created four additional SSVs. Two of the
new SSVs are associated with VORs: VOR Low (VL) and VOR High (VH), as shown in FIG 1-1-4. The other
two new SSVs are associated with DME: DME Low (DL) and DME High (DH), as shown in FIG 1-1-5. The
SSV at altitudes below 1,000 feet for the VL and VH are the same as FIG 1-1-3. The SSVs at altitudes below
12,900 feet for the DL and DH SSVs correspond to a conservative estimate of the DME radio line of sight (RLOS)
coverage at each altitude (not including possible terrain blockage).

1-1-8

Navigation Aids