background image

862 

14 CFR Ch. I (1–1–19 Edition) 

§ 171.311 

T

ABLE

8a—B

ASIC

D

ATA

W

ORDS

—Continued 

Data bit 

Data item definition 

LSB 

value 

Data bit 

value 

Note 1: 

Transmit throughout the Approach Azimuth guidance 

sector at intervals of 1.0 seconds or less. 

Note 2: 

The all zero state of the data field represents the 

lower limit of the absolute range of the coded parameter 
unless otherwise noted. 

Basic Data Word No. 4 

1 Preamble .........................

N/A 

2 ..........................................

............

3 ..........................................

............

4 ..........................................

............

5 ..........................................

............

6 ..........................................

............

7 ..........................................

............

8 ..........................................

............

9 ..........................................

............

10 ..........................................

............

11 ..........................................

............

12 ..........................................

............

13 

Approach azimuth mag-

netic orientation (0

° 

to 

359

°

).

1

° 

1

° 

14 ..........................................

............

2

° 

15 ..........................................

............

4

° 

16 ..........................................

............

8

° 

17 ..........................................

............

16

° 

18 ..........................................

............

32

° 

19 ..........................................

............

64

° 

20 ..........................................

............

128

° 

21 ..........................................

............

256

° 

22 

Back azimuth magnetic 

orientation (0

° 

to 359

°

).

1

° 

1

° 

23 ..........................................

............

2

° 

24 ..........................................

............

4

° 

25 ..........................................

............

8

° 

26 ..........................................

............

16

° 

27 ..........................................

............

32

° 

28 ..........................................

............

64

° 

29 ..........................................

............

128

° 

30 ..........................................

............

256

° 

31 

Parity: (13 + 14 + 15. . . 

+ 30 + 31 = odd).

N/A N/A 

32 

Parity: (14 + 16 + 18. . . 

+ 30 + 32 = odd).

N/A N/A 

Note 1: 

Transmit at intervals of 1.0 second or less through-

out the Approach Azimuth guidance sector, except when 
Back Azimuth guidance is provided. See Note 8. 

Note 2: 

The all zero state of the data field represents the 

lower limit of the absolute range of the coded parameter 
unless otherwise noted. 

Basic Data Word No. 5 

1 Preamble .........................

N/A 

2 ..........................................

............

3 ..........................................

............

4 ..........................................

............

5 ..........................................

............

6 ..........................................

............

7 ..........................................

............

8 ..........................................

............

9 ..........................................

............

10 ..........................................

............

11 ..........................................

............

12 ..........................................

............

13 

Back azimuth proportional 

coverage negative limit 
(0

° 

to 

¥

42

°

).

2

° 

¥

2

° 

14 ..........................................

............

¥

4

° 

15 ..........................................

............

¥

8

° 

T

ABLE

8a—B

ASIC

D

ATA

W

ORDS

—Continued 

Data bit 

Data item definition 

LSB 

value 

Data bit 

value 

16 ..........................................

............

¥

16

° 

17 ..........................................

............

¥

32

° 

18 

Back azimuth proportional 

coverage positive limit 
(0

° 

to + 42

°

).

2

° 

2

° 

19 ..........................................

............

4

° 

20 ..........................................

............

8

° 

21 ..........................................

............

16

° 

22 ..........................................

............

32

° 

23 

Back azimuth beamwidth 

(0.5

° 

to 4.0

°

) See note 

7.

0.5

° 

0.5

° 

24 ..........................................

............

1.0

° 

25 ..........................................

............

2.0

° 

26 

Back azimuth status ........

............

See Note 10 

27 ......do ...............................

............

Do. 

28 ......do ...............................

............

Do. 

29 ......do ...............................

............

Do. 

30 ......do ...............................

............

Do. 

31 

Parity: (13 + 14 + 15. . . 

+ 30 + 31 = odd).

N/A N/A 

32 

Parity: (14 + 16 + 18. . . 

+ 30 + 32 = odd).

N/A N/A 

Note 1: 

Transmit only when Back Azimuth guidance is pro-

vided. See note 9. 

Note 2: 

The all zero state of the data filed represents the 

lower limit of the absolute range of the coded parameter 
unless otherwise noted. 

Basic Data Word No. 6 

1 Preamble .........................

N/A 

2 ..........................................

............

3 ..........................................

............

4 ..........................................

............

5 ..........................................

............

6 ..........................................

............

7 ..........................................

............

8 ..........................................

............

9 ..........................................

............

10 ..........................................

............

11 ..........................................

............

12 ..........................................

............

(13– 
30) 

MLS ground equipment 

identification (Note 3).

............

13 Character 

2 ......................

N/A 

B1 

14 ..........................................

............

B2 

15 ..........................................

............

B3 

16 ..........................................

............

B4 

17 ..........................................

............

B5 

18 ..........................................

............

B6 

19 Character 

3 ......................

N/A 

B1 

20 ..........................................

............

B2 

21 ..........................................

............

B3 

22 ..........................................

............

B4 

23 ..........................................

............

B5 

24 ..........................................

............

B6 

25 Character 

4 ......................

N/A 

B1 

26 ..........................................

............

B2 

27 ..........................................

............

B3 

28 ..........................................

............

B4 

29 ..........................................

............

B5 

30 ..........................................

............

B6 

31 

Parity: (13 + 14 + 15. . . 

+ 30 + 31 = odd).

N/A N/A 

32 

Parity: (14 + 16 + 18. . . 

+ 30 + 32 = odd).

N/A N/A 

Note 1: 

Transmit at intervals of 1.0 second or less through-

out the Approach Azimuth guidance sector, except when Back 
Azimuth guidance is provided. See note 8. 

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