Citace z jineho zdroje - manual k B737 NG, Continental Airlines (ma to traged na strance)
Procedure Turn – DME Arc
A DME arc is the track of an aircraft maintained at a constant distance from a navigational aid by reference to distance measuring equipment (DME).
The distinguishing feature of the DME arc is you are required to fly your aircraft along a circular track around the VORTAC station at a specified distance.
Many transitions, which incorporate DME arcs, are already included in the FMS database and may be selectable by choosing the appropriate approach transition.
Note: A DME arc may be created on the Map by selecting a distance reference (mileage) for a desired FIX page waypoint.
When turning onto an arc, plan to lead your turn to avoid overshooting the desired arc. A good rule-of-thumb is to lead desired DME indication by 1% of your ground speed.
Example: For a 200-knot ground speed, lead 2 miles, and so forth.
Keeping a bearing or radial indicator near the wing tip will keep you close to the desired arc. Flying in a series of short, straight legs are usually the best technique to use. Do not attempt to fly in a continuous bank.
The DME indication will be the same as the published DME distance each time the VOR-RDMI needle passes through the wing tip position. If you drift off the ARC:
If getting closer to the station than desired, turn to put the station behind of the wing tip.
If getting further from the station than desired, turn to put the station ahead of the wing tip.
Technically speaking, correct 10° for each ½ mile outside the arc, and 5° for each ½ mile inside the arc.
Since a graphic presentation of the station’s position is important to flying a DME arc, do not attempt this maneuver with the bearing indicator inoperative.
For most DME transitions, a lead of approximately 10 degrees will be adequate for turning from the arc to the final approach course (at 15 NM from the station, 10 degrees of arc is equivalent to 2½ NM).
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