Let's say you are 10,000 feet on an IFR flight plan and ATC tells you to fly direct to a high altitude VOR that is greater than 40 NM away. ..IE... you are beyond the Standard Service Volume of the VOR according to the AIM. You tune and identify it, center the CDI...all looks good...BUT...Because you are not on a published route and you are beyond the Standard Service Volume of 40 NM and you are a slant Alpha (IE...no RNAV or GPS)...are you allowed to accept the clearance or legally should you remind ATC you are a slant A and request a vector until able? Refer to AIM 1-1-8(a). I'm looking for legality here rather than practicality. Practiaclly...yeah...just center the CDI and go to the VOR... but is it legal if you are beyond the Standard Service Volume?Thanks in advance for all sincere responces.
Legally you need only be able to fix your position reliably. You can do that with dead reckoning well enough, as you can with a radar vector, an electrical position fix, or a star reading for that matter (for those of us that remember). Or by pilotage.
Ask for a vector. Look at your chart. Start timing and use your heading...you still do that, don't you? Is this legal? You betcha.
You asked about OpSpecs...these are applicable to a particular operator and only to that operator, but you got lucky and picked the right one. You picked OpSpec A002, which includes the definition for Operational Service Volume, as follows:
The Operational Service Volume is that volume of airspace surrounding a NAVAID which is available for operational use and within which a signal of useable strength exists and where that signal is not operational limited by co-chanel interference. Operational Service Volume includes all of the following:
(1) The officially designated Standard Service Volume excluding any portion of the Standard Service Volume which has been restricted.
(2) The Expanded Service Volume.
(3) Within the United States, any published instrument flight proceedure (victor or jet airway, SID, STAR, SIAP, or instrument departure).
(4) Outside the United States, any designated signal coverage or published instrument flight proceedure equivilent to U.S. Standards.
This echoes AC 91-70, which includes the note, "The operational service volume for a specific navaid can be determined by contacting the Frequency Management Section within each regional Airway Facilities Division." Note that the Operational Service Volume includes any airway.
Yes, the OpSpecs you cited do reference Class 1 navigation and address your questions, but only if you're employed by the company to whom each one is issued. They are operator-specific, and not intended as general definition or regulation. In fact, they are allowances to regulation, additions thereof that apply only to the single, specific certificate holder who receives them. These apply to Part 121, 125, 129, and 135 operators. Sister authorizations that mirror the OpSpecs are issued to Fractional operators now, operating under 14 CFR Part 91 subpart K...called "M" specs for "management specifications."
Advisory Circular 90-92, Appendix 2, provides the following definition for Extended Service Volume:
Extended Service Volume - Defines the reception limits of VOR/DME and NDB NAVAIDs which are usable for unpublished route navigation and which are flight checked to confirm these limits of coverage. The extended service volume of NDBs used in oceanic navigation (such as beyond the 75 nm standard service volume) must be individually flight checked. There is no procedure readily available to pilots to help them determine whether or not a particular charted offshore route has an extended service volume. However, air traffic separation is based on DR beyond the extended service volume, so the pilot uses the NAVAID for as long as possible, establishes the wind drift rate, then uses LRN or DR.
The widespread use of long range navigation has largely made this a non-issue. However, in keeping with the original question posed by the thread, if we consider an aircraft that isn't equipped with long range navigation, I have to assume that the pilot is certainly equipped with the capability of establishing his position by dead reckoning...basic navigational skills that should be ingrained at the student-pilot level. Are you legal to include DR in your navigational reportoire? You betcha. Can you? That's up to you. May you? You betcha. Should you? Only if you dont' want thick layers of rust to grow up around all those important skills that you buried after you got your wet ink pilot certificate.
The bottom line for you, if you're flying A to B under strictly Part 91, is that you need to be able to know (A) where you are, and (B) where you're going, and (C) how to get there. If you can do that, you can get there legally. You need to have an approved means to do that. If you're navigating by victor radios (your VOR) and you can receive and identify the navaid you're using, then you're in good shape. You are never prohibited from DR and other basic forms of navigation. Even modern GPS and FMS equipment utilizes DR for navigation...you can, too.
Remember too that you may not be within the standard, extended, or operational service volumes of the navaids from which or to which you're going, but you may be able to fix your position from numerous navaids adjacent to your course. So long as you can fix your position reliably, by the means at your disposal, then you're legal, and more importantly, safe.
As other posters have noted, in a radar environment, you can obtain a single vector across the country if you like, and be in and out of reception of naviads all the while, and be legal. Likewise, if you can fix your position by other means, such as fix to fix using triangualtion from enroute nav stations, a mixture of VOR's and NDB's along your route, and dead reckoning, you're also legal...and might I add, capable.
