In what case AIS Message Type 3 should be transmitted?

[Wittgenstein]

Hi, I am a new comer. Having read the discussion on the topic of "Shipping Containers on*Radar," I come to join here to get your helps.

My recent interest is focused on 27 types of*AIS*messages, especially on*AIS*message type 3, which was transmitted in the critical moment of the sunken Ferry Sewol on the western sea of S.Korea.

The usage of AIS Message Type 3, which I found through surfing the*Internet, is as follows :

(1) "AIS Message 3 is a special or interrogation position report that is commanded*using AIS message 15"

(2) "Message 3*transmission*is ITDMA based and is used*when a ship is announcing a need for extra slots due to increased reporting rate,*
usually related to a change in speed or cruising direction."*

Here, my puzzle is "Is the above (1) and (2) just the same case, or two separate cases?"

The answer to the puzzle, I think, may solve the cause of the Sunken Ferry Sewol incident on April 16 2016.

I need a clear answer from you, AIS users.

The below raw data of AIS Message Type 3 is of the sunken*Ferry*Sewol on April 16 2014.*

$IEC01,VTS1004,4403318,P,0,20140416084837|!AIVDM,1 ,1,,B,16SWOT002ga0VwpCS9L5B4Fv2D9:,0*0B^65
$IEC03,VTS1004,4403310,P,0,20140416084913|!AIVDM,1 ,1,,B,36SWOT0Ojc90Wj@CS3i5eDdJ20sQ,0*6D^0E
$IEC03,VTS1004,4403310,P,0,20140416084919|!AIVDM,1 ,1,,B,36SWOT0Oja90WojCS2kmm4nV20wh,0*48^5F
$IEC03,VTS1004,4403310,P,0,20140416084919|!AIVDM,1 ,1,,A,36SWOT0Oja90WojCS2kmm4nV21Ri,0*6E^06
$IEC03,VTS1004,4403318,P,0,20140416084919|!AIVDM,1 ,1,,B,36SWOT0Oja90WojCS2kmm4nV20wh,0*48^57
$IEC03,VTS1004,4403318,P,0,20140416084919|!AIVDM,1 ,1,,A,36SWOT0Oja90WojCS2kmm4nV21Ri,0*6E^0E
$IEC03,VTS1004,4403310,P,0,20140416084925|!AIVDM,1 ,1,,B,36SWOT0OjW90WtdCS1mEv52j2271,0*27^36
$IEC03,VTS1004,4403310,P,0,20140416084926|!AIVDM,1 ,1,,B,36SWOT0OjW90WuJCS1c60E4l2000,0*47^53
$IEC03,VTS1004,4403310,P,0,20140416084930|!AIVDM,1 ,1,,A,36SWOT0OjU90WwtCS10n=m<t20q0,0*05^10
$IEC03,VTS1004,4403310,P,0,20140416084931|!AIVDM,1 ,1,,A,36SWOT0OjU90WwtCS10n=m>j22h1,0*03^11
$IEC03,VTS1004,4403308,P,0,20140416084936|!AIVDM,1 ,1,,A,36SWOT0OjP90`1vCRww6`UU82000,0*2A^46
$IEC03,VTS1004,4403310,P,0,20140416084937|!AIVDM,1 ,1,,B,36SWOT0OjN90`26CRwlFdma:23@A,0*17^06
$IEC03,VTS1004,4403310,P,0,20140416084956|!AIVDM,1 ,1,,A,36SWOT0Oj?a0Ww`CRumWaW;P2000,0*06^10
$IEC03,VTS1004,4403318,P,0,20140416084956|!AIVDM,1 ,1,,A,36SWOT0Oj?a0Ww`CRumWaW;P2000,0*06^18
$IEC03,VTS1004,4403318,P,0,20140416085016|!AIVDM,1 ,1,,A,36SWOT0Oica0We<CRspaQGnB2000,0*5D^38
$IEC03,VTS1004,4403318,P,0,20140416085019|!AIVDM,1 ,1,,A,36SWOT0Oica0WcDCRsi9bWtJ21OQ,0*4C^20
$IEC03,VTS1004,4403318,P,0,20140416085020|!AIVDM,1 ,1,,B,36SWOT0Oica0WcDCRsi9bWtJ210P,0*31^22
$IEC03,VTS1004,4403310,P,0,20140416085025|!AIVDM,1 ,1,,B,36SWOT0Oica0WWTCRsaaiH4T227Q,0*0A^67
$IEC03,VTS1004,4403318,P,0,20140416085025|!AIVDM,1 ,1,,B,36SWOT0Oica0WWTCRsaaiH4T227Q,0*0A^6F
$IEC03,VTS1004,4403318,P,0,20140416085026|!AIVDM,1 ,1,,B,36SWOT0Oiba0WTLCRsTasp4T2000,0*63^71
$IEC03,VTS1004,4403318,P,0,20140416085031|!AIVDM,1 ,1,,A,36SWOT0Oiaa0WNPCRsOb<p<f22lQ,0*37^22
$IEC03,VTS1004,4403318,P,0,20140416085037|!AIVDM,1 ,1,,B,36SWOT0Oi`a0WHTCRsM:IH>r23Ai,0*22^35
$IEC03,VTS1004,4403310,P,0,20140416085037|!AIVDM,1 ,1,,B,36SWOT0Oi`a0WHTCRsM:IH>r23Ai,0*22^3D
$IEC03,VTS1004,4403310,P,0,20140416085046|!AIVDM,1 ,1,,B,36SWOT0Oi`a0W>pCRsObdpC<2000,0*27^3B
$IEC03,VTS1004,4403310,P,0,20140416085050|!AIVDM,1 ,1,,A,36SWOT0Oiaa0W<dCRsObg8E@20v@,0*34^2D
$IEC03,VTS1004,4403318,P,0,20140416085050|!AIVDM,1 ,1,,A,36SWOT0Oiaa0W<dCRsObg8E@20v@,0*34^25
$IEC03,VTS1004,4403318,P,0,20140416085056|!AIVDM,1 ,1,,A,36SWOT0Oiba0W30CRsd;2pMR2000,0*2F^4B
$IEC03,VTS1004,4403310,P,0,20140416085057|!AIVDM,1 ,1,,A,36SWOT0Oiba0W30CRsd;2pMR2000,0*2F^42
$IEC03,VTS1004,4403310,P,0,20140416085100|!AIVDM,1 ,1,,B,36SWOT0Oiba0W18CRsi;6`QV20uh,0*3A^52
$IEC03,VTS1004,4403318,P,0,20140416085100|!AIVDM,1 ,1,,B,36SWOT0Oiba0W18CRsi;6`QV20uh,0*3A^5A
$IEC03,VTS1004,4403318,P,0,20140416085109|!AIVDM,1 ,1,,A,36SWOT0PAWa0VmTCRt<cRGj42110,0*07^1B
$IEC03,VTS1004,4403310,P,0,20140416085109|!AIVDM,1 ,1,,A,36SWOT0PAWa0VmTCRt<cRGj42110,0*07^13
$IEC03,VTS1004,4403318,P,0,20140416085113|!AIVDM,1 ,1,,B,36SWOT0PAVa0Vl`CRtAcUWh620vA,0*6D^0F
$IEC03,VTS1004,4403310,P,0,20140416085116|!AIVDM,1 ,1,,A,36SWOT0PATa0VilCRtKcgof<2000,0*56^48
$IEC03,VTS1004,4403318,P,0,20140416085116|!AIVDM,1 ,1,,A,36SWOT0PATa0VilCRtKcgof<2000,0*56^40
$IEC03,VTS1004,4403310,P,0,20140416085125|!AIVDM,1 ,1,,B,36SWOT0PALa0VbDCRtvd8GdN22:Q,0*3A^55
$IEC03,VTS1004,4403318,P,0,20140416085125|!AIVDM,1 ,1,,B,36SWOT0PALa0VbDCRtvd8GdN22:Q,0*3A^5D
$IEC03,VTS1004,4403310,P,0,20140416085130|!AIVDM,1 ,1,,A,36SWOT0PAGa0VUtCRuJ<FGbb20uh,0*70^6E
$IEC03,VTS1004,4403318,P,0,20140416085130|!AIVDM,1 ,1,,A,36SWOT0PAGa0VUtCRuJ<FGbb20uh,0*70^66
$IEC03,VTS1004,4403310,P,0,20140416085131|!AIVDM,1 ,1,,A,36SWOT0PAGa0VUtCRuJ<FGbb22hA,0*46^5C
$IEC03,VTS1004,4403310,P,0,20140416085136|!AIVDM,1 ,1,,A,36SWOT0PABa0VRlCRuk<S7bn2000,0*3F^55
$IEC03,VTS1004,4403310,P,0,20140416085137|!AIVDM,1 ,1,,B,36SWOT0PAAa0VQpCRuu<`obr23AQ,0*5A^30
$IEC03,VTS1004,4403318,P,0,20140416085137|!AIVDM,1 ,1,,B,36SWOT0PAAa0VQpCRuu<`obr23AQ,0*5A^38
$IEC03,VTS1004,4403310,P,0,20140416085144|!AIVDM,1 ,1,,A,36SWOT001<a0VNhCRvK<moc623mA,0*7A^16
$IEC03,VTS1004,4403310,P,0,20140416085146|!AIVDM,1 ,1,,B,36SWOT001<a0VNhCRvK<moc>2000,0*5E^36
$IEC03,VTS1004,4403318,P,0,20140416085146|!AIVDM,1 ,1,,B,36SWOT001<a0VNhCRvK<moc>2000,0*5E^3E
$IEC03,VTS1004,4403318,P,0,20140416085149|!AIVDM,1 ,1,,A,36SWOT0019a0VMPCRvb<rocB2120,0*2A^46
$IEC03,VTS1004,4403318,P,0,20140416085156|!AIVDM,1 ,1,,A,36SWOT0015a0VKDCRw8=5WcJ2000,0*1A^7B
$IEC03,VTS1004,4403310,P,0,20140416085156|!AIVDM,1 ,1,,A,36SWOT0015a0VKDCRw8=5WcJ2000,0*1A^73
$IEC03,VTS1004,4403310,P,0,20140416085200|!AIVDM,1 ,1,,B,36SWOT0011a0VIhCRwNe=ocV212h,0*6A^04
$IEC03,VTS1004,4403318,P,0,20140416085206|!AIVDM,1 ,1,,B,36SWOT000va0VHlCRwh=C7cl2000,0*10^06
$IEC03,VTS1004,4403310,P,0,20140416085207|!AIVDM,1 ,1,,B,36SWOT000va0VHlCRwh=C7cl2000,0*10^0F
$IEC03,VTS1004,4403318,P,0,20140416085210|!AIVDM,1 ,1,,A,36SWOT000sa0VGTCS0;eI7b220v0,0*7F^1E
$IEC03,VTS1004,4403310,P,0,20140416085210|!AIVDM,1 ,1,,A,36SWOT000sa0VGTCS0;eI7b220v0,0*7F^16
$IEC01,VTS1004,4403318,P,0,20140416085213|!AIVDM,1 ,1,,B,16SWOT000ra0VG@CS0@eKGb626s@,0*15^00
$IEC01,VTS1004,4403310,P,0,20140416085213|!AIVDM,1 ,1,,B,16SWOT000ra0VG@CS0@eKGb626s@,0*15^08
$IEC03,VTS1004,4403318,P,0,20140416085216|!AIVDM,1 ,1,,A,36SWOT000qa0VFtCS0M=OWb<2000,0*5C^3C

[JohnT]

Recreational cruising boats use AIS Class B, which generally does not support AIS messaging. You need to put your query to somebody who has studied AIS Class A - I.e. Somebody in the commercial shipping world and not the recreational cruising folk.

[Franziska]

Try the GCaptain forum.

www.ladyrover.com