Common Errors - P-8710066

CHAPTER FOUR

T-6A INSTRUMENT NAVIGATION

9. As the aircraft approaches the point, it will be necessary to determine whether you will

reach the radial or the DME first. To come as close as possible to the new point, it will be

necessary to judge the rate at which the DME is moving and the rate at which you are crossing

radials. If determined one rate is moving faster than the other, it may be the aircraft will reach

the DME or radial first rather than simultaneously. Keep the following in mind when trying to

hit a point:

DME Rate of Change. When the bearing pointer is closer to the heading index than

the 90 benchmark, i.e., above the 45 benchmark, the DME will change faster than

the radials. The opposite is true when the bearing pointer is nearer the 90

benchmark, i.e., when the bearing pointer is below the 45 benchmark.

Remember, unless the winds are very strong, when the head of the bearing

pointer is above the 90 benchmark, the DME will get smaller. When the head

of the bearing pointer is below the 90 benchmark, the DME will probably get

larger.

ii.

To get your DME to "speed up," turn to place the bearing pointer closer to the

heading index. This will slow the rate at which you are crossing radials. When

going inbound, you will be working with the head of the bearing pointer. When

going outbound, you will be working with the tail.

Radial Rate of Change. To cross radials faster, turn to place the bearing pointer

closer to the 90 benchmark. This will slow the rate of DME change.

You will not necessarily be able to determine the exact heading to roll out on as

you are adjusting heading, but that is not as important as altering your heading

before it is too late. Once on your new heading, let things settle down (cross a

few radials, and let a few tenths of DME pass). Then update again by trying to

determine if you will hit the radial or DME first.

ii.

Your goal is to get as close as you can to the desired point. Continually update

until crossing the point.

10. In the event your solution does not work out exactly, you may arrive either at your desired

DME or radial prior to the fix. Regardless of which comes first, you can consider yourself at the

fix once within the distance required by course standards.

COMMON ERRORS

1. Failing to expedite the first step. Remember there is plenty of time to refine your solution

once proceeding in the general direction.

2. Failing to make frequent updates. As you get closer to the station, more updates will be

required to ensure an accurate solution.

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