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rkaplan
Administrator
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Posted: Wed Jan 25th, 2006 12:59 am |
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The VNAV feature can be very helpful when flying a non-precision approach with the Garmin 430/530. If you set up the VNAV page to guide you to 0 feet / 0 miles from a waypoint and then you set VSR (Vertical Speed Required) as a field on one of your nav pages, then the VSR display on an approach will show you the required minimum descent rate to reach the missed approach point.
However, the VSR output turns off inside the final approach fix. A workaround to fix this is to press the OBS key after you pass the final aproach fix. The reason for this is that pressing the OBS key deactivates the approach, which permits the VSR guidance to resume.
Note that you SHOULD NOT do this for a GPS approach where the GPS is the legal primary navigation equipment. You should only do this on a non-GPS approach (i.e. VOR or LOC approach) where the GPS provides advisory guidance only and the VOR or LOC signal provides primary navigational guidance.
____________________
Richard Kaplan, CFII
rkaplan@flyimc.com
http://www.flyimc.com
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Joe Jenkins
Member
| Joined: | Wed Jan 25th, 2006 |
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| Posts: | 2 |
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Offline
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Posted: Wed Jan 25th, 2006 09:01 pm |
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Dr Kaplan,
A method that I was taught to me to avoid the dive and drive method on a non-precison approach is to take your distance out multiply by three and add field elevation. Ever heard of this?
Joe
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rkaplan
Administrator
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Posted: Thu Jan 26th, 2006 03:36 am |
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Joe Jenkins wrote:
A method that I was taught to me to avoid the dive and drive method on a non-precison approach is to take your distance out multiply by three and add field elevation. Ever heard of this?
Yes, that will work. It is based on the idea that an airplane on a typical 3-degree glideslope loses about 330 feet per mile or 1,000 feet per 3 miles.
Note I think these techniques work well in VFR conditions but in low IMC conditions I still think dive-and-drive (i.e. 800 FPM descent) is best in a piston airplane. You want to get down to MDA as soon as possible so you can begin to slow the airplane and look for the approach lights and runway.
____________________
Richard Kaplan, CFII
rkaplan@flyimc.com
http://www.flyimc.com
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rkaplan
Administrator
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Posted: Thu Jan 26th, 2006 03:36 am |
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Joe Jenkins wrote:
A method that I was taught to me to avoid the dive and drive method on a non-precison approach is to take your distance out multiply by three and add field elevation. Ever heard of this?
Yes, that will work. It is based on the idea that an airplane on a typical 3-degree glideslope loses about 330 feet per mile or 1,000 feet per 3 miles.
Note I think these techniques work well in VFR conditions but in low IMC conditions I still think dive-and-drive (i.e. 800 FPM descent) is best in a piston airplane. You want to get down to MDA as soon as possible so you can begin to slow the airplane and look for the approach lights and runway.
____________________
Richard Kaplan, CFII
rkaplan@flyimc.com
http://www.flyimc.com
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Joe Jenkins
Member
| Joined: | Wed Jan 25th, 2006 |
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| Posts: | 2 |
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Offline
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Posted: Thu Jan 26th, 2006 02:36 pm |
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Thanks for the reply. Better to be at or near MDA than to be above it still on a descent.
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