הליך ונוסחת קצה כנף

"חוק קצה כנף" הנו הליך חישובי מהיר, קל ולא מדויק, (בדומה לחוק 1/60), המאפשר חישוב מרחק לתחנה משדרת, כאשר המטוס חוצה בניצב בקרוב, שני רדיאלים הידועים לו

זמן לתחנה המשדרת=השינוי הזוויתי במעלות/זמן שחלף בשניות בין שני הרדיאלים

VOR TRACKING (Course Following)

To follow a desired course inbound or outbound with wind unknown, use this procedure:

1. Set OBS to desired course. When the desired course has been intercepted, with the COl centered, maintain a heading corresponding to the OBS.

2. When definite off course position is indicated by the COl, turn 20° in the direction of the COl.

Maintain this heading until needles re-centers

3. When the needle centers, turn 10° towards course selected on OBS. This establishes a 10° wind correction angle. If the COl remains centered, maintain heading. Wind correction angle is correct.

4. If the COl again indications off course position in the same direction, wind correction angle is insufficient. Turn to the same heading used in the 20° correction. When the needle re-centers, turn 5° in the opposite direction. This establishes a 15° wind correction angle.

5. Conversely, if the COl deflects opposite to the initial deflection, the 10° wind correction angle is too great. In this case, parallel the course. When the aircraft has drifted back on course, COl centered, establish a 5° wind correction angle

6. After heading is established in accord with step or steps 3, 4, 5, as required, heading corrections of 5° are normally adequate to keep the COl centered. To obtain the ultimate accuracy, heading corrections of less than 5° are required.

IMPORTANT

If the first 20° change of heading toward the course fails to re-center the COl within a reasonable period of time, another 20° heading should be made toward the COl to accumulate a correction of 40°.

(A strong crosswind is indicated) When the COl re-centers, establish a 20° wind correction angle. Correct this angle as necessary, using the same technique as above.

AIDS TO COURSE FOLLOWING:

Following a VOR radial is a trial and error process in which a series of headings are used to determine the desired course. Finding this course depends on each successive trial heading based on the results of previous headings. A new trial heading should not be established until the results of the previous trial heading

have been determined.

When flying toward a VOR and the COl retains a constant off course indication, that heading will cause the aircraft to intercept the course at the station. This causes the aircraft to converge on the course. In this situation, the aircraft should be turned 5° toward the course and this correction maintained until the COl recenters.

Then turn back to the heading that held the COl in a constant position.

CAUTION:

When the OBS heading and the aircraft heading are reciprocals, a condition commonly referred to as "reverse sensing occurs.

Example: An aircraft flying to or from a VOR on a heading of 090° with the OBS set to 270°. If the aircraft is to the left of the course, the COl will be deflected left, and if the aircraft is right of the course, the COl will be deflected to the right. In this situation, turns must be made away from the needle in order to intercept the course. This is the opposite of the procedure normally used in course following, thus the term "reverse sensing.

This is why we:

Track toward a VOR with a "TO" indication

Track away from a VOR with a "FROM" indication

VOR COURSE INTERCEPTION PROCEDURES

These procedures are used when it is desired to intercept a course that does not coincide with the present location of the aircraft.

To Intercept a Course "TO" A VOR Facility:

1. Tune in and Identify the desired facility, then turn volume down

2. Turn the aircraft to a heading Parallel to the desired course

3. Center the COl with "TO" indication if tracking Inbound or "From" if tracking Outbound

4. Determine the difference between the centered COl and your desired course.

a. If course is Less than 30° difference use a 45° intercept

b. If course is More than 30° difference use a 90° intercept

5. Turn OBS to desired course. Note: The COl will indicate the proper direction to turn the aircraft.

6. Turn the aircraft - 45° or 90° toward the needle (COl)

VOR TIME CHECK

This is an expanded explanation of the wing tip bearing changes (90°) method of execution of VOR time check as shown in the FAA Instrument Flying Handbook AC 61-27.

The formula solution is applied to the elapsed time for a predetermined change in azimuth from the aircraft to a station located at 90° from the aircraft heading.

Execution:

1. Tune in and Identify with the desired VOR station

2. Center the COl with the OBS with a "TO" Indication

3. Turn the aircraft to heading corresponding to the course indicated on the OBS. (The radius of this turn may take the aircraft slightly off the original inbound course indicated on the OBS, therefore, step 4 follows)

4. Re-center COl with OBS (still with a "TO" reading) and correct heading to correspond with this reading. The nose of the aircraft is pointed at the station.

5. Turn the aircraft 80° to the right of the inbound heading assumed in Step 4. Turn the course selector 10° counterclockwise. (Opposite the direction of turn, COl needle will be deflected right the same as the direction of the turn)

6. Maintain heading. When the COl centers, note the time.

7. Maintain heading. Rotate the OBS 10° counterclockwise. (The COl needle will again be deflected right)

8. When COl again centers, note time and compute elapsed time from Step 6.

9. Turn the aircraft to track to the station.

10. As the turn in Step 9 is initiated, compute time to station, using one of the following formulas:

By analysis of the above formula we derive the following:

Time to station in minutes equals minutes flown to obtain 10° bearing change multiplied by 6.

Time to Station (In minutes) = Time Flown in Seconds

Degrees of Bearing Change

By analysis of the above formula, we note that the time to station in minutes equals 1/10 of the time flown in seconds for 10° bearing change. For example, if a 10° wing tip bearing change takes 80 seconds, time to station is 8 minutes.

NOTE: The tum indicated in Step 5 of the foregoing procedure may in practice be made either right or left, keeping in mind that the OBS is turned counterclockwise in case of a right turn and clockwise for a left turn.

However, to simplify standardization it is recommended that during initial training this tum be made to the right.

Illustration

Steps Indicated in Above Illustration

1 Center COl with "TO' and tum to heading same as course shown on OBS

2 Re-center COl and correct heading to agree with OBS.

• OBS 290°, Heading 290°

3 Tum aircraft 80° right, OBS 10° counterclockwise

• OBS 280°, Heading 010°

4 COl centers, start time, then tum OBS 10° further counterclockwise

• OBS 270°, Heading 010°

5 COl centers, stop time, start tum toward station and compute time to station

6 Give estimate to station

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