# holding the centreline

ken hanson (veshagoo) Trainee

hi guys...any help would be appreciated....on final with just about all the airplanes , say about 14 miles out or so i never can hold the airplane on the centreline of the runway i am always CHASING THE GAUGES ....i have no problem with the glideslope just the localizer...thanks ken

## 4 Responses

CRJCapt Chief Captain

The localizer is very sensitive. Use the reference direction( 100 degrees for ILS 10) of the ILS as you starting point and bracket the course. Only use a max of 10 degrees correction(5 degrees within 5 miles of the runway). If you have wind, once you get back to the center of the course, you will have to select a heading that is within the bracket that you have just created. You know that the reference heading(100) won't hold the course and 110 is too much. You fly 105 once on course and watch to see what happens. If it goes left- fly 100 until it centers, if it goes right- fly 110 until it centers.

You should practice VOR tracking first, you use the same technique but it's less sensitive at least at a distance. When you get close to the VOR(less than 2 miles), the course become sensitive like a localizer. That's why it's good practice.

ken hanson (veshagoo) Trainee

thanks for the reply sori what is ...bracket the course... mean thanks ken

CRJCapt Chief Captain

By bracket I mean that you set two values(left and right) that you know won't work. This means that the value you want must be somewhere between the two.

Let's say your on the LOC course of the ILS 12 approach holding a heading of 120 degrees. Your CDI needle starts to drift right(your course is right), there is a wind blowing from 180 degrees that is moving you to the left of the course. 120 becomes one side of the bracket. Now you need to choose a value that you think will overcome the wind and move you to the right to get back on the course. No set value for this, depends on how hard you think the wind is blowing. Choose 10 degrees to start, you can increase it if you don't start moving toward the course. So you turn to a heading of 130. That is your bracket(120-130). You should not have to turn outside of those two headings. As the course centers, choose a heading that you think may work that's between 120-130, 125.
If you then start to drift left again, you only have to turn to 130 because you know it will get you back to the course. If you drift right, turn to 120 and let the wind move you to your course. When you get back to your course, you have determined a new, smaller bracket( either 125-130 or 120-125) depending on if you drifted left or right. That's bracketing the course. It keeps you from making huge, unneeded heading changes by helping you deduce the needed heading.

Last edited by CRJCapt on Sat Jun 16, 2007 11:20 pm, edited 1 time in total

ken hanson (veshagoo) Trainee

yet once more...thanks very much crjcapt...i will try this.....makes very good sense.....appreciate your replys rgds ken

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