Parameter

Number

of bits

Description

Encryption

Status

Function ID

5

2 = Overlay, Option 1

AES encrypted

Overlay Type

4

0 = Expanding Square 1 = Sector

2 = Parallel Line 3 = Creeping Line

4-5 = not allowed [for use with FID 3] 6 = Circle

7-15 = undefined

AES encrypted

Overlay Number

5

Sender generated (0-31)

AES encrypted

Center/Origin Longitude

25

Longitude to nearest 1/1000 min (±180 degrees; East = positive; West = negative; 181 degrees = not available =

default) [± 1.8 meter accuracy]

AES encrypted

Center/Origin Latitude

24

Latitude to nearest 1/1000 min (±90 degrees; North = positive; South =

negative; 91 degrees = not available = default) [± 1.8 meter accuracy]

AES encrypted

Radius/Length

17

0000.01-1310.72 nautical miles; Radius dimension for Expanding Square, Sector & Circle Overlays, Length dimension for Parallel & Creeping Line Overlays

AES encrypted

Width

17

Width 0000.01-1310.72 nautical miles;

0000.00 = not Parallel Line or Creeping Line Pattern

AES encrypted

Orientation

9

Major axis direction in degrees (0-359);

AES encrypted

Number of sectors

7

Number of sectors, up to 128; 0 = not a Sector Pattern

AES encrypted

Track Spacing

14

Track Spacing 000.01-163.84;

000.00 = Sector Pattern, Polygon or single trackline

AES encrypted

First turn

1

0 = left; 1 = right

AES encrypted

Search Speed

10

Specified search speed in knots;

0 = default = not applicable/specified.

AES encrypted

Search Altitude

12

Specified search altitude in feet;

0 = default = not applicable/specified.

AES encrypted

Unused bits set to zero

90

Unused bits set to zero are inserted so that the number of bits in the encrypted field is a multiple of 128 bits.

AES encrypted

Checksum

16

Cyclic Redundancy Check (CRC) 16-bit polynomial

AES encrypted

TOTAL

256

256 encrypted bits

AES encrypted