Add Label B9 ATIS Request decoder plugin

lib/MessageDecoder.ts

@@ -78,6 +78,7 @@ const pluginClasses = [
   Plugins.Label_QQ,
   Plugins.Label_QR,
   Plugins.Label_QS,
+  Plugins.Label_B9_ATIS_Request,
 ];
 
 export class MessageDecoder {

lib/plugins/Label_B9_ATIS_Request.ts

@@ -0,0 +1,197 @@
+import { DecoderPlugin } from '../DecoderPlugin';
+import { DecodeResult, Message, Options } from '../DecoderPluginInterface';
+
+/**
+ * Label B9 — ATIS Request (downlink, aircraft → ground)
+ *
+ * The aircraft asks a named ground station's ATIS service (sub-type TI2
+ * = Terminal Information v2) for the current ATIS broadcast. This is a
+ * short, formatted request carrying the target airport, an opaque
+ * sequence/parameter field, and a trailing integrity checksum.
+ *
+ * Wire format:
+ *
+ *   / EDDK . TI2 / 024 EDDK A 6 61A
+ *   | |    | |   | |   |    | | |
+ *   | |    | |   | |   |    | | └── Checksum / trailer (2–4 hex-like chars; likely CRC)
+ *   | |    | |   | |   |    | └──── Sub-qualifier (single alphanumeric)
+ *   | |    | |   | |   |    └────── ATIS information letter (A–Z, Alpha..Zulu)
+ *   | |    | |   | |   └─────────── Repeated airport ICAO (echo of target)
+ *   | |    | |   | └─────────────── Sequence / parameter field (3-digit, e.g. 024, 040, 000)
+ *   | |    | |   └───────────────── Delimiter
+ *   | |    | └───────────────────── Sub-type / service code (typ. TI2)
+ *   | |    └─────────────────────── Delimiter
+ *   | └──────────────────────────── Target ground station airport ICAO (4 chars)
+ *   └────────────────────────────── Preamble / sub-format indicator '/'
+ *
+ * Examples observed in the wild:
+ *   /EDDK.TI2/024EDDKA661A   (Cologne Bonn, Germany)
+ *   /KADW.TI2/024KADWA53E9   (Joint Base Andrews)
+ *   /EGLL.TI2/000EGLLAABB2   (Heathrow)
+ *   /KLAX.TI2/024KLAXDB1CC
+ *   /KSFO.TI2/040KSFOCBE89
+ */
+export class Label_B9_ATIS_Request extends DecoderPlugin {
+  name = 'label-b9-atis-request';
+
+  qualifiers() {
+    return {
+      labels: ['B9'],
+    };
+  }
+
+  decode(message: Message, options: Options = {}): DecodeResult {
+    const decodeResult = this.initResult(
+      message,
+      'ATIS Request (aircraft → ground-station ATIS service)',
+    );
+
+    const text = (message.text || '').trim();
+    if (!text) {
+      this.setDecodeLevel(decodeResult, false);
+      return decodeResult;
+    }
+
+    // Primary shape: /ICAO.SUBTYPE/SEQ(3d) ICAO(4) LETTER(1) SUBQ(1) CHK(2..4)
+    const regex =
+      /^\/(?<gs>[A-Z]{4})\.(?<subtype>[A-Z0-9]+)\/(?<seq>\d{3})(?<echo>[A-Z]{4})(?<letter>[A-Z])(?<subq>[A-Z0-9])(?<chk>[A-Z0-9]{2,4})$/;
+    const m = text.match(regex);
+
+    if (!m?.groups) {
+      // Partial fallback — pull just the leading /ICAO.SUBTYPE/ header if present
+      const hdr = text.match(/^\/([A-Z]{4})\.([A-Z0-9]+)\//);
+      if (hdr) {
+        decodeResult.raw.preamble = '/';
+        decodeResult.raw.ground_station_icao = hdr[1];
+        decodeResult.raw.atis_subtype = hdr[2];
+        decodeResult.raw.arrival_icao = hdr[1];
+        decodeResult.formatted.items.push(
+          {
+            type: 'message_type',
+            code: 'MSGTYP',
+            label: 'Message Type',
+            value: 'ATIS Request — downlink to ground-station ATIS service',
+          },
+          {
+            type: 'ground_station',
+            code: 'GNDSTN',
+            label: 'Ground Station ICAO',
+            value: hdr[1],
+          },
+          {
+            type: 'atis_subtype',
+            code: 'SUBTYPE',
+            label: 'Sub-type / Service',
+            value: hdr[2] === 'TI2' ? 'TI2 (Terminal Information v2)' : hdr[2],
+          },
+        );
+        decodeResult.remaining.text = text.substring(hdr[0].length);
+        this.setDecodeLevel(decodeResult, true, 'partial');
+        return decodeResult;
+      }
+      this.setDecodeLevel(decodeResult, false);
+      return decodeResult;
+    }
+
+    const { gs, subtype, seq, echo, letter, subq, chk } = m.groups;
+
+    decodeResult.raw.preamble = '/';
+    decodeResult.raw.ground_station_icao = gs;
+    decodeResult.raw.atis_subtype = subtype;
+    decodeResult.raw.sequence = seq;
+    decodeResult.raw.payload_echo_icao = echo;
+    decodeResult.raw.atis_letter = letter;
+    decodeResult.raw.atis_subqualifier = subq;
+    decodeResult.raw.checksum = chk;
+    decodeResult.raw.arrival_icao = gs;
+
+    const subtypeLabel =
+      subtype === 'TI2' ? 'TI2 (Terminal Information v2)' : subtype;
+
+    decodeResult.formatted.items = [
+      {
+        type: 'message_type',
+        code: 'MSGTYP',
+        label: 'Message Type',
+        value: 'ATIS Request — downlink to ground-station ATIS service',
+      },
+      {
+        type: 'ground_station',
+        code: 'GNDSTN',
+        label: 'Ground Station ICAO',
+        value: gs,
+      },
+      {
+        type: 'atis_subtype',
+        code: 'SUBTYPE',
+        label: 'Sub-type / Service',
+        value: subtypeLabel,
+      },
+      {
+        type: 'sequence',
+        code: 'SEQ',
+        label: 'Sequence / Parameter',
+        value: seq,
+      },
+      {
+        type: 'payload_echo',
+        code: 'ECHO',
+        label: 'Payload Target ICAO',
+        value: echo + (echo === gs ? ' (echoes target)' : ' (differs from header)'),
+      },
+      {
+        type: 'atis_letter',
+        code: 'ATIS_LETTER',
+        label: 'ATIS Info Letter',
+        value: `${letter} (${this.phonetic(letter)})`,
+      },
+      {
+        type: 'atis_subqualifier',
+        code: 'ATIS_SUBQ',
+        label: 'Sub-qualifier',
+        value: subq,
+      },
+      {
+        type: 'checksum',
+        code: 'CHK',
+        label: 'Checksum',
+        value: chk,
+      },
+    ];
+
+    this.setDecodeLevel(decodeResult, true, 'full');
+    return decodeResult;
+  }
+
+  private phonetic(letter: string): string {
+    const names: Record<string, string> = {
+      A: 'Alpha',
+      B: 'Bravo',
+      C: 'Charlie',
+      D: 'Delta',
+      E: 'Echo',
+      F: 'Foxtrot',
+      G: 'Golf',
+      H: 'Hotel',
+      I: 'India',
+      J: 'Juliet',
+      K: 'Kilo',
+      L: 'Lima',
+      M: 'Mike',
+      N: 'November',
+      O: 'Oscar',
+      P: 'Papa',
+      Q: 'Quebec',
+      R: 'Romeo',
+      S: 'Sierra',
+      T: 'Tango',
+      U: 'Uniform',
+      V: 'Victor',
+      W: 'Whiskey',
+      X: 'X-ray',
+      Y: 'Yankee',
+      Z: 'Zulu',
+    };
+    return names[letter.toUpperCase()] || letter;
+  }
+}

lib/plugins/official.ts

@@ -64,3 +64,4 @@ export * from './Label_QR';
 export * from './Label_QP';
 export * from './Label_QS';
 export * from './Label_QQ';
+export * from './Label_B9_ATIS_Request';