866
14 CFR Ch. I (1–1–19 Edition)
§ 171.313
T
ABLE
8
C
—A
UXILIARY
D
ATA
—Continued
Word
(See
note 6)
Data content
Type
of data
Maximun
time be-
tween trans-
missions
(Seconds)
Bits
used
Range of values
Least
sig-
nifi-
cant
bit
Back azimuth antenna alignment with run-
way centerline.
...........
....................
12
¥
20.47
°
to 20.47
°
(See note 3) ..
0.01
°
Spare ...........................................................
...........
....................
16 ......................................................
.........
Parity ............................................................
...........
....................
7 (See note 1) .................................
.........
N
OTE
1: Parity bits I
70
to I
76
are chosen to
satisfy the equations which follow:
For BIT I
70
:
Even = (I
13
+ ... + I
18
) + I
20
+ I
22
+ I
24
+ I
25
+ I
28
+ I
29
+ I
31
+ I
32
+ I
33
+ I
35
+ I
36
+ I
38
+ I
41
+ I
44
+ I
45
+ I
46
+ I
50
+ (I
52
+ ... + I
55
) + I
58
+
I
60
+ I
64
+ I
65
+ I
70
For BIT I
71
:
Even = (I
14
+ ... + I
19
) + I
21
+ I
23
+ I
25
+ I
26
+ I
29
+ I
30
+ I
32
+ I
33
+ I
34
+ I
36
+ I
37
+ I
39
+ I
42
+ I
45
+ I
46
+ I
47
+ I
51
+ (I
53
+ ... + I
56
) + I
59
+
I
61
+ I
65
+ I
66
+ I
71
For BIT I
72
:
Even = (I
15
+ ... + I
20
) + I
22
+ I
24
+ I
26
+ I
27
+ I
30
+ I
31
+ I
33
+ I
34
+ I
35
+ I
37
+ I
38
+ I
40
+ I
43
+ I
46
+ I
47
+ I
48
+ I
52
+ (I
54
+ ... + I
57
) + I
60
+
I
62
+ I
66
+ I
67
+ I
72
For BIT I
73
:
Even = (I
16
+ ... + I
21
) + I
23
+ I
25
+ I
27
+ I
28
+ I
31
+ I
32
+ I
34
+ I
35
+ I
36
+ I
38
+ I
39
+ I
41
+ I
44
+ I
47
+ I
48
+ I
49
+ I
53
+ (I
55
+ ... + I
58
) + I
61
+
I
63
+ I
67
+ I
68
+ I
73
For BIT I
74
:
Even = (I
17
+ ... + I
22
) + I
24
+ I
26
+ I
28
+ I
29
+ I
32
+ I
33
+ I
35
+ I
36
+ I
37
+ I
39
+ I
40
+ I
42
+ I
45
+ I
48
+ I
49
+ I
50
+ I
54
+ (I
56
+ ... + I
59
) + I
62
+
I
64
+ I
68
+ I
69
+ I
74
For BIT I
75
:
Even = (I
13
+ ... + I
17
) + I
19
+ I
21
+ I
23
+ I
24
+ I
27
+ I
28
+ I
30
+ I
31
+ I
32
+ I
34
+ I
35
+ I
37
+ I
40
+ I
43
+ I
44
+ I
45
+ I
49
+ (I
51
+ ... + I
54
) + I
57
+
I
59
+ I
63
+ I
64
+ I
69
+ I
75
For BIT I
76
:
Even = I
13
+ I
14
+ ... + I
75
+ I
76
N
OTE
2: Code for I
56
is: 0 = conical; 1 =
planar.
N
OTE
3: The convention for the coding of
negative numbers is as follows:
¥
MSB is the
sign bit; 0 = + ; 1 =
¥
.
—Other bits represent the absolute value.
The convention for the antenna location is
as follows: As viewed from the MLS approach
reference datum looking toward the datum
point, a positive number shall represent a lo-
cation to the right of the runway centerline
(lateral offset) or above the runway (vertical
offset), or towards the stop end of the run-
way (longitudinal distance).
The convention for the antenna alignment
is as follows: As viewed from above, a posi-
tive number shall represent clockwise rota-
tion from the runway centerline to the re-
spective zero-degree guidance plane.
N
OTE
4: Data Word A3 is transmitted at in-
tervals of 1.0 seconds or less throughout the
approach Azimuth coverage sector, except
when back Azimuth guidance is provided.
Where back Azimuth is provided transmit at
intervals of 1.33 seconds or less throughout
the approach Azimuth sector and 4.0 seconds
or less throughout the back Azimuth cov-
erage sector.
N
OTE
5: When back Azimuth guidance is
provided, transmit at intervals of 1.33 sec-
onds or less throughout the back Azimuth
coverage sector and 4.0 seconds or less
throughout the approach Azimuth coverage
sector.
N
OTE
6: The designation ‘‘A1’’ represents
the function identification code for ‘‘Auxil-
iary Data A’’ and address code number 1.
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