Welcome Guest. Sign in or Signup

5 Answers

COP, no DME onboard

Asked by: 1926 views Instrument Rating

Salutations,

So i'm planning an IFR flight here and my aircraft is without gps and dme.  How do I determine the change over point between vor stations?  There is actually no COP for that segment, and I know of course that means I switch halfway between stations, but how do I know when I'm there?  If I had to guess I'd say to go by the estimated flight time and divide by two, but then I am trusting totally the winds aloft forecast.  Is there a better way?

Thanks!

 

Ace Any FAA Written Test!
Actual FAA Questions / Free Lifetime Updates
The best explanations in the business
Fast, efficient study.
Pass Your Checkride With Confidence!
FAA Practical Test prep that reflects actual checkrides.
Any checkride: Airplane, Helicopter, Glider, etc.
Written and maintained by actual pilot examiners and master CFIs.
The World's Most Trusted eLogbook
Be Organized, Current, Professional, and Safe.
Highly customizable - for student pilots through pros.
Free Transition Service for users of other eLogs.
Our sincere thanks to pilots such as yourself who support AskACFI while helping themselves by using the awesome PC, Mac, iPhone/iPad, and Android aviation apps of our sponsors.

5 Answers



  1. Bobby on May 26, 2013

    Either use 1/2 of leg time, or a radial off another VOR (if available).

    0 Votes Thumb up 0 Votes Thumb down 0 Votes



  2. Mark Kolber on May 26, 2013

    Guesstimating the COP is fine. The sole purpose of a COP (charted or midpoint) is to ensure a usable signal; if you’re getting one, there’s no “you shall change navaids now!” involved. And, if you make the switch and get a weak signal and a wavering needle and flag, you’d switch back even if you were beyond the COP, wouldn’t you?

    And, of course, other equipment can be used to determine location..

    • Have 2 VORs? Why not simply tune in the second VOR to the next frequency. When it’s strong and consistent, make the switch. That’s what I did when flying no-DME/no-GPS aircraft.
    • With 2 VORs or an NDB, you can also use a crossing radial or bearing (just like you learned as a private pilot).
    • Have a handheld GPS for situational awareness? Use that.

    +3 Votes Thumb up 3 Votes Thumb down 0 Votes



  3. Jason on May 26, 2013

    Got it, thanks guys. I guess I just thought it strange that it’s not really covered in the instrument procedures, or instrument flying handbooks. Anyways, sounds like it will work out fine. Thank you

    0 Votes Thumb up 0 Votes Thumb down 0 Votes



  4. Ale on May 31, 2013

    In addition to the valuable comments above, I suggest you make a receiver sensitivity check. How?

    When your time calculation “tells” you are about to reach the 1/2 way point, switch to the VOR ahead of you and check your on-board VOR receiver sensitivity (i.e. the closer you are to a VOR station, the faster the VOR needle moves). Compare the receiving sensitivity from the two VORs (the one ahead compared to the one behind) and keep the one with the stronger signals; obviously at some point, the VOR ahead will have stronger signal; this is the time to permanently change to it.

    0 Votes Thumb up 0 Votes Thumb down 0 Votes



  5. Ale on May 31, 2013

    P.S.
    Please note that changing to the next VOR just because you receive its signals is technically wrong. That is because the on-board VOR receive indication (i.e the needle) won’t be accurate enough when the signals are receivable but weak.

    This can cause a serious navigation inaccuracy which might result in flying out of the airway protected airspace and that is when the ATC alerts you about that (e.g. C172 you are flying 2 miles left of the airway boundaries).

    0 Votes Thumb up 0 Votes Thumb down 0 Votes


Answer Question

Our sincere thanks to all who contribute constructively to this forum in answering flight training questions. If you are a flight instructor or represent a flight school / FBO offering flight instruction, you are welcome to include links to your site and related contact information as it pertains to offering local flight instruction in a specific geographic area. Additionally, direct links to FAA and related official government sources of information are welcome. However we thank you for your understanding that links to other sites or text that may be construed as explicit or implicit advertising of other business, sites, or goods/services are not permitted even if such links nominally are relevant to the question asked.