diff --git a/libraries/DataFlash/DataFlash.h b/libraries/DataFlash/DataFlash.h
index 9749c8c21c..d62c61ecb1 100644
--- a/libraries/DataFlash/DataFlash.h
+++ b/libraries/DataFlash/DataFlash.h
@@ -358,6 +358,7 @@ struct PACKED log_EKF1 {
     float velN;
     float velE;
     float velD;
+    float posD_dot;
     float posN;
     float posE;
     float posD;
@@ -817,7 +818,7 @@ Format characters in the format string for binary log messages
     { LOG_SIMSTATE_MSG, sizeof(log_AHRS), \
       "SIM","QccCfLL","TimeUS,Roll,Pitch,Yaw,Alt,Lat,Lng" }, \
     { LOG_EKF1_MSG, sizeof(log_EKF1), \
-      "EKF1","QccCffffffccc","TimeUS,Roll,Pitch,Yaw,VN,VE,VD,PN,PE,PD,GX,GY,GZ" }, \
+      "EKF1","QccCfffffffccc","TimeUS,Roll,Pitch,Yaw,VN,VE,VD,dPD,PN,PE,PD,GX,GY,GZ" }, \
     { LOG_EKF2_MSG, sizeof(log_EKF2), \
       "EKF2","Qbbbcchhhhhh","TimeUS,Ratio,AZ1bias,AZ2bias,VWN,VWE,MN,ME,MD,MX,MY,MZ" }, \
     { LOG_EKF3_MSG, sizeof(log_EKF3), \
@@ -827,7 +828,7 @@ Format characters in the format string for binary log messages
     { LOG_EKF5_MSG, sizeof(log_EKF5), \
       "EKF5","QBhhhcccCC","TimeUS,normInnov,FIX,FIY,AFI,HAGL,offset,RI,meaRng,errHAGL" }, \
     { LOG_NKF1_MSG, sizeof(log_EKF1), \
-      "NKF1","QccCffffffccc","TimeUS,Roll,Pitch,Yaw,VN,VE,VD,PN,PE,PD,GX,GY,GZ" }, \
+      "NKF1","QccCfffffffccc","TimeUS,Roll,Pitch,Yaw,VN,VE,VD,dPD,PN,PE,PD,GX,GY,GZ" }, \
     { LOG_NKF2_MSG, sizeof(log_NKF2), \
       "NKF2","Qbccccchhhhhh","TimeUS,AZbias,GSX,GSY,GSZ,VWN,VWE,MN,ME,MD,MX,MY,MZ" }, \
     { LOG_NKF3_MSG, sizeof(log_NKF3), \
diff --git a/libraries/DataFlash/LogFile.cpp b/libraries/DataFlash/LogFile.cpp
index b96aa6bc32..93a3402912 100644
--- a/libraries/DataFlash/LogFile.cpp
+++ b/libraries/DataFlash/LogFile.cpp
@@ -1144,10 +1144,12 @@ void DataFlash_Class::Log_Write_EKF(AP_AHRS_NavEKF &ahrs, bool optFlowEnabled)
     Vector3f dAngBias;
     Vector3f dVelBias;
     Vector3f gyroBias;
+    float posDownDeriv;
     ahrs.get_NavEKF().getEulerAngles(euler);
     ahrs.get_NavEKF().getVelNED(velNED);
     ahrs.get_NavEKF().getPosNED(posNED);
     ahrs.get_NavEKF().getGyroBias(gyroBias);
+    ahrs.get_NavEKF().getPosDownDerivative(posDownDeriv);
     struct log_EKF1 pkt = {
         LOG_PACKET_HEADER_INIT(LOG_EKF1_MSG),
         time_us : hal.scheduler->micros64(),
@@ -1157,6 +1159,7 @@ void DataFlash_Class::Log_Write_EKF(AP_AHRS_NavEKF &ahrs, bool optFlowEnabled)
         velN    : (float)(velNED.x), // velocity North (m/s)
         velE    : (float)(velNED.y), // velocity East (m/s)
         velD    : (float)(velNED.z), // velocity Down (m/s)
+        posD_dot : (float)(posDownDeriv), // first derivative of down position
         posN    : (float)(posNED.x), // metres North
         posE    : (float)(posNED.y), // metres East
         posD    : (float)(posNED.z), // metres Down
@@ -1294,10 +1297,12 @@ void DataFlash_Class::Log_Write_EKF2(AP_AHRS_NavEKF &ahrs, bool optFlowEnabled)
     Vector3f dAngBias;
     Vector3f dVelBias;
     Vector3f gyroBias;
+    float posDownDeriv;
     ahrs.get_NavEKF2().getEulerAngles(euler);
     ahrs.get_NavEKF2().getVelNED(velNED);
     ahrs.get_NavEKF2().getPosNED(posNED);
     ahrs.get_NavEKF2().getGyroBias(gyroBias);
+    ahrs.get_NavEKF2().getPosDownDerivative(posDownDeriv);
     struct log_EKF1 pkt = {
         LOG_PACKET_HEADER_INIT(LOG_NKF1_MSG),
         time_us : hal.scheduler->micros64(),
@@ -1307,6 +1312,7 @@ void DataFlash_Class::Log_Write_EKF2(AP_AHRS_NavEKF &ahrs, bool optFlowEnabled)
         velN    : (float)(velNED.x), // velocity North (m/s)
         velE    : (float)(velNED.y), // velocity East (m/s)
         velD    : (float)(velNED.z), // velocity Down (m/s)
+        posD_dot : (float)(posDownDeriv), // first derivative of down position
         posN    : (float)(posNED.x), // metres North
         posE    : (float)(posNED.y), // metres East
         posD    : (float)(posNED.z), // metres Down