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A Circling Approach is normally
made, when the
executed Instrument Approach Procedure serves another runway, other than the
Landing runway. This normally means decision height and visibility is much more
stringent. You must not depart from the procedure unless you have the runway in
sight. If you do lose sight of the airport, then you will have to carry out
the missed approach procedure immediately. Some of the approaches to airfields
are on DME Arc distances from the VOR . This lecture is about teaching you how to
do a circling approach using a VOR/DME Arc IE vectoring yourself
round an arc onto a final approach course at 16 miles out all the way
round until intercepting the inbound radial. The inbound course for this
exercise back to the VOR will be the 195 radial on a heading of 015 .
Pick any VOR of your choice, position yourself overhead and fly outbound on the
085 radial to the VOR 15 DME. You will then need to turn 100 degrees to the right
heading 185. The reason you turn one mile away is because the aircraft will
still push you out to 16 DME in the turn . Likewise if you coming from another VOR
towards this VOR you would start your 100 degree left turn at 17 miles Now
rotate the OBS needle on your VOR instrument until it centres with a TO sign
showing. Keep Adjusting the OBS to keep the needle in the centre. Each time you
have done ten degrees on the OBS indication ,turn your aircraft right ten degrees
and reset the needle to the centre . Repeat the procedure each time you have
done 10 degrees until you get round to the required heading to fly inbound to
the VOR . In this case it is 015, then turn right and fly back in to the VOR. When
you are happy doing it to the right, try doing it to the left.
RULE OF THUMB Your heading until intercepting should
always be 100 degrees more than the radial shown at the bottom of the
instrument.
If the DME read out is more than 16 DME , add
another couple of degrees onto it to the right say 13 degrees instead of 10 degrees
next time to correct it. If the DME readout is less then turn a few degrees to
the left IE 7 degrees instead of 10 degrees. This is normally caused by wind
drift . On the last 10 degrees of interception you will need to set the VOR OBS to
015 ready for the inbound leg. This time keep the needle centred, then fly
inbound to the VOR allowing for Drift.
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