Technical Provisions for Mode S Services and Extended Squitter

DRAFT - Working Paper ASP TSGWP11-01 for review by the TSG during the meeting in June 2011 in Paris
C-36 Technical Provisions for Mode S Services and Extended Squitter
Table C-30. A/V Length and Width Code
A/V - L/W
Length Code Width Upper-Bound Length and Width
Code
Code
for Each Length/Width Code
(Decimal) “ME” “ME” “ME” “ME” Length
Width
Bit 49 Bit 50 Bit 51 Bit
52
(meters)
(meters)
0 0 0 0 0 No Data or Unknown
1 0 0 0 1 15 23
2
3
0 0 1
0
1
25
28.5
34
4
5
0 1 0
0
1
35
33
38
6
7
0 1 1
0
1
45
39.5
45
8
9
1 0 0
0
1
55
45
52
10
11
1 0 1
0
1
65
59.5
67
12
13
1 1 0
0
1
75
72.5
80
14
15
1 1 1
0
1
85
80
90
If the Aircraft or Vehicle is longer than 85 meters, or wider than 90 meters, then decimal Aircraft/Vehicle
Length/Width Code 15 shall be used.
Note.— For example, consider a powered glider with overall length of 24 meters and wingspan of
50 meters. Normally, an aircraft of that length would be in length category 1 (that is, have a length code of
1). But since the wingspan exceeds 34 meters, it does not qualify for even the “wide” subcategory (width
code = 1) of length category 1. Such an aircraft would be assigned length code = 4 and width code = 1,
meaning “length less than 55 meters and width less than 52 meters.”
C.2.3.10.12 Track Angle/Heading
The Track Angle/Heading is a 1-bit (“ME” bit 53, Message bit 85) subfield of the ADS-B Aircraft Operational
Status Message (Subtype=1, for Surface Participants) that allows correct interpretation of the data contained
in the Heading/Ground Track subfield of the ADS-B Surface Position Message when the Air/Ground status is
determined to be in the “On-Ground” state as indicated in §3.1.2.6.10.1.2 of Annex 10, Vol. IV.
Draft
C.2.3.10.13 Horizontal Reference Direction (HRD)
This 1-bit (“ME” bit 54, Message bit 86) subfield will be used to indicate the reference direction (true north or
magnetic north) for horizontal directions such as Heading, Track Angle. The Horizontal Reference Direction
subfield will be encoded as specified in Table C-31.
Table C-31. Horizontal Reference Direction (HRD) Encoding
HRD Value Meaning
0 True North
1 Magnetic North
C.2.3.10.14 System Design Assurance (SDA)
The position transmission chain includes the ADS-B transmission equipment, ADS-B processing equipment,
position source, and any other equipment that processes the position data and position quality metrics that
shall be transmitted.
DRAFT - Working Paper ASP TSGWP11-01 for review by the TSG during the meeting in June 2011 in Paris