Merge pull request #33 from openskynetwork/ground-status

Better decoding and documentation for airborne/ground status

src/main/java/org/opensky/libadsb/msgs/AllCallReply.java

@@ -83,6 +83,25 @@ public byte getCapabilities() {
 		return capabilities;
 	}
 
+	/**
+	 * @return whether capabilities indicate that aircraft is on the ground.
+	 * Note that returning false does not indicate that the aircraft is airborne as status might be unknown!
+	 * See also {@link #isAirborne()}.
+	 */
+	public boolean isOnGround() {
+		return capabilities == 4;
+	}
+
+	/**
+	 * @return whether capabilities indicate that aircraft is airborne.
+	 * Note that returning false does not indicate that the aircraft is on ground as status might be unknown!
+	 * See also {@link #isOnGround()}.
+	 */
+	public boolean isAirborne() {
+		return capabilities == 5;
+	}
+
+
 	/**
 	 * Some receivers already subtract the crc checksum
 	 * from the parity field right after reception.

src/main/java/org/opensky/libadsb/msgs/AltitudeReply.java

@@ -111,13 +111,23 @@ public boolean hasSPI() {
 	}
 
 	/**
-	 * @return whether flight status indicates that aircraft is
-	 * airborne or on the ground; For flight status >= 4, this flag is unknown
+	 * @return whether flight status indicates that aircraft is on the ground.
+	 * For flight status >= 4, this flag is unknown. Thus, a return value of false
+	 * does not indicate that the aircraft is airborne! See also {@link #isAirborne()}.
 	 */
 	public boolean isOnGround() {
 		return flight_status==1 || flight_status==3;
 	}
 
+	/**
+	 * @return whether flight status indicates that aircraft is airborne.
+	 * For flight status >= 4, this flag is unknown. Thus, a return value of false
+	 * does not indicate that the aircraft is on ground! See also {@link #isOnGround()} .
+	 */
+	public boolean isAirborne() {
+		return flight_status == 0 || flight_status == 2;
+	}
+
 	/**
 	 * indicator for downlink requests
 	 * @return the 5 bits downlink request. The coding is:<br>

src/main/java/org/opensky/libadsb/msgs/CommBAltitudeReply.java

@@ -118,13 +118,23 @@ public boolean hasSPI() {
 	}
 
 	/**
-	 * @return whether flight status indicates that aircraft is
-	 * airborne or on the ground; For flight status >= 4, this flag is unknown
+	 * @return whether flight status indicates that aircraft is on the ground.
+	 * For flight status >= 4, this flag is unknown. Thus, a return value of false
+	 * does not indicate that the aircraft is airborne! See also {@link #isAirborne()}.
 	 */
 	public boolean isOnGround() {
 		return flight_status==1 || flight_status==3;
 	}
 
+	/**
+	 * @return whether flight status indicates that aircraft is airborne.
+	 * For flight status >= 4, this flag is unknown. Thus, a return value of false
+	 * does not indicate that the aircraft is on ground! See also {@link #isOnGround()} .
+	 */
+	public boolean isAirborne() {
+		return flight_status == 0 || flight_status == 2;
+	}
+
 	/**
 	 * indicator for downlink requests
 	 * @return the 5 bits downlink request. The coding is:<br>

src/main/java/org/opensky/libadsb/msgs/CommBIdentifyReply.java

@@ -118,13 +118,23 @@ public boolean hasSPI() {
 	}
 
 	/**
-	 * @return whether flight status indicates that aircraft is
-	 * airborne or on the ground; For flight status >= 4, this flag is unknown
+	 * @return whether flight status indicates that aircraft is on the ground.
+	 * For flight status >= 4, this flag is unknown. Thus, a return value of false
+	 * does not indicate that the aircraft is airborne! See also {@link #isAirborne()}.
 	 */
 	public boolean isOnGround() {
 		return flight_status==1 || flight_status==3;
 	}
 
+	/**
+	 * @return whether flight status indicates that aircraft is airborne.
+	 * For flight status >= 4, this flag is unknown. Thus, a return value of false
+	 * does not indicate that the aircraft is on ground! See also {@link #isOnGround()} .
+	 */
+	public boolean isAirborne() {
+		return flight_status == 0 || flight_status == 2;
+	}
+
 	/**
 	 * indicator for downlink requests
 	 * @return the 5 bits downlink request. The coding is:<br>

src/main/java/org/opensky/libadsb/msgs/IdentifyReply.java

@@ -111,13 +111,23 @@ public boolean hasSPI() {
 	}
 
 	/**
-	 * @return whether flight status indicates that aircraft is
-	 * airborne or on the ground; For flight status >= 4, this flag is unknown
+	 * @return whether flight status indicates that aircraft is on the ground.
+	 * For flight status >= 4, this flag is unknown. Thus, a return value of false
+	 * does not indicate that the aircraft is airborne! See also {@link #isAirborne()}.
 	 */
 	public boolean isOnGround() {
 		return flight_status==1 || flight_status==3;
 	}
 
+	/**
+	 * @return whether flight status indicates that aircraft is airborne.
+	 * For flight status >= 4, this flag is unknown. Thus, a return value of false
+	 * does not indicate that the aircraft is on ground! See also {@link #isOnGround()} .
+	 */
+	public boolean isAirborne() {
+		return flight_status == 0 || flight_status == 2;
+	}
+
 	/**
 	 * indicator for downlink requests
 	 * @return the 5 bits downlink request. The coding is:<br>