diff --git a/src/modules/interface/crtp_commander_high_level.h b/src/modules/interface/crtp_commander_high_level.h
index 9ee0c3a830..542028ab02 100644
--- a/src/modules/interface/crtp_commander_high_level.h
+++ b/src/modules/interface/crtp_commander_high_level.h
@@ -52,6 +52,8 @@ Header file for high-level commander that computes smooth setpoints based on hig
 #define TRAJECTORY_MEMORY_SIZE 4096
 extern uint8_t trajectories_memory[TRAJECTORY_MEMORY_SIZE];
 
+#define NUM_TRAJECTORY_DEFINITIONS 10
+
 /* Public functions */
 void crtpCommanderHighLevelInit(void);
 
diff --git a/src/modules/src/crtp_commander_high_level.c b/src/modules/src/crtp_commander_high_level.c
index f582978a5c..32c574e186 100644
--- a/src/modules/src/crtp_commander_high_level.c
+++ b/src/modules/src/crtp_commander_high_level.c
@@ -55,8 +55,34 @@ such as: take-off, landing, polynomial trajectories.
 #include "log.h"
 #include "param.h"
 
+// Local types
+enum TrajectoryLocation_e {
+  TRAJECTORY_LOCATION_INVALID = 0,
+  TRAJECTORY_LOCATION_MEM     = 1, // for trajectories that are uploaded dynamically
+  // Future features might include trajectories on flash or uSD card
+};
+
+enum TrajectoryType_e {
+  TRAJECTORY_TYPE_POLY4D = 0, // struct poly4d, see pptraj.h
+  // Future types might include versions without yaw
+};
+
+struct trajectoryDescription
+{
+  uint8_t trajectoryLocation; // one of TrajectoryLocation_e
+  uint8_t trajectoryType;     // one of TrajectoryType_e
+  union
+  {
+    struct {
+      uint32_t offset;  // offset in uploaded memory
+      uint8_t n_pieces;
+    } __attribute__((packed)) mem; // if trajectoryLocation is TRAJECTORY_LOCATION_MEM
+  } trajectoryIdentifier;
+} __attribute__((packed));
+
 // Global variables
 uint8_t trajectories_memory[TRAJECTORY_MEMORY_SIZE];
+static struct trajectoryDescription trajectory_descriptions[NUM_TRAJECTORY_DEFINITIONS];
 
 static bool isInit = false;
 static struct planner planner;
@@ -78,6 +104,7 @@ enum TrajectoryCommand_e {
   COMMAND_STOP                    = 3,
   COMMAND_GO_TO                   = 4,
   COMMAND_START_TRAJECTORY        = 5,
+  COMMAND_DEFINE_TRAJECTORY       = 6,
 };
 
 struct data_set_group_mask {
@@ -114,33 +141,21 @@ struct data_go_to {
   float duration; // sec
 } __attribute__((packed));
 
-enum TrajectoryLocation_e {
-  TRAJECTORY_LOCATION_MEM = 0, // for trajectories that are uploaded dynamically
-  // Future features might include trajectories on flash or uSD card
-};
-
-enum TrajectoryType_e {
-  TRAJECTORY_TYPE_POLY4D = 0, // struct poly4d, see pptraj.h
-  // Future types might include versions without yaw
-};
-
 // starts executing a specified trajectory
 struct data_start_trajectory {
   uint8_t groupMask; // mask for which CFs this should apply to
   uint8_t relative;  // set to true, if trajectory should be shifted to current setpoint
   uint8_t reversed;  // set to true, if trajectory should be executed in reverse
-  uint8_t trajectoryLocation; // one of TrajectoryLocation_e
-  uint8_t trajectoryType;     // one of TrajectoryType_e
-  union
-  {
-    struct {
-      uint32_t offset;  // offset in uploaded memory
-      uint8_t n_pieces;
-    } __attribute__((packed)) mem; // if trajectoryLocation is TRAJECTORY_LOCATION_MEM
-  } trajectoryIdentifier;
+  uint8_t trajectoryId; // id of the trajectory (previously defined by COMMAND_DEFINE_TRAJECTORY)
   float timescale; // time factor; 1 = original speed; >1: slower; <1: faster
 } __attribute__((packed));
 
+// starts executing a specified trajectory
+struct data_define_trajectory {
+  uint8_t trajectoryId;
+  struct trajectoryDescription description;
+} __attribute__((packed));
+
 // Private functions
 static void crtpCommanderHighLevelTask(void * prm);
 
@@ -150,6 +165,7 @@ static int land(const struct data_land* data);
 static int stop(const struct data_stop* data);
 static int go_to(const struct data_go_to* data);
 static int start_trajectory(const struct data_start_trajectory* data);
+static int define_trajectory(const struct data_define_trajectory* data);
 
 // Helper functions
 static struct vec state2vec(struct vec3_s v)
@@ -258,6 +274,9 @@ void crtpCommanderHighLevelTask(void * prm)
       case COMMAND_START_TRAJECTORY:
         ret = start_trajectory((const struct data_start_trajectory*)&p.data[1]);
         break;
+      case COMMAND_DEFINE_TRAJECTORY:
+        ret = define_trajectory((const struct data_define_trajectory*)&p.data[1]);
+        break;
       default:
         ret = ENOEXEC;
         break;
@@ -328,32 +347,44 @@ int go_to(const struct data_go_to* data)
 int start_trajectory(const struct data_start_trajectory* data)
 {
   int result = 0;
-  if (isInGroup(data->groupMask)
-    && data->trajectoryLocation == TRAJECTORY_LOCATION_MEM
-    && data->trajectoryType == TRAJECTORY_TYPE_POLY4D) {
-    xSemaphoreTake(lockTraj, portMAX_DELAY);
-    float t = usecTimestamp() / 1e6;
-    trajectory.t_begin = t;
-    trajectory.timescale = data->timescale;
-    trajectory.n_pieces = data->trajectoryIdentifier.mem.n_pieces;
-    trajectory.pieces = (struct poly4d*)&trajectories_memory[data->trajectoryIdentifier.mem.offset];
-    if (data->relative) {
-      trajectory.shift = vzero();
-      struct traj_eval traj_init;
-      if (data->reversed) {
-        traj_init = piecewise_eval_reversed(&trajectory, trajectory.t_begin);
-      }
-      else {
-        traj_init = piecewise_eval(&trajectory, trajectory.t_begin);
+  if (isInGroup(data->groupMask)) {
+    if (data->trajectoryId < NUM_TRAJECTORY_DEFINITIONS) {
+      struct trajectoryDescription* trajDesc = &trajectory_descriptions[data->trajectoryId];
+      if (   trajDesc->trajectoryLocation == TRAJECTORY_LOCATION_MEM
+          && trajDesc->trajectoryType == TRAJECTORY_TYPE_POLY4D) {
+        xSemaphoreTake(lockTraj, portMAX_DELAY);
+        float t = usecTimestamp() / 1e6;
+        trajectory.t_begin = t;
+        trajectory.timescale = data->timescale;
+        trajectory.n_pieces = trajDesc->trajectoryIdentifier.mem.n_pieces;
+        trajectory.pieces = (struct poly4d*)&trajectories_memory[trajDesc->trajectoryIdentifier.mem.offset];
+        if (data->relative) {
+          trajectory.shift = vzero();
+          struct traj_eval traj_init;
+          if (data->reversed) {
+            traj_init = piecewise_eval_reversed(&trajectory, trajectory.t_begin);
+          }
+          else {
+            traj_init = piecewise_eval(&trajectory, trajectory.t_begin);
+          }
+          struct vec shift_pos = vsub(pos, traj_init.pos);
+          trajectory.shift = shift_pos;
+        } else {
+          trajectory.shift = vzero();
+        }
+        result = plan_start_trajectory(&planner, &trajectory, data->reversed);
+        xSemaphoreGive(lockTraj);
       }
-      struct vec shift_pos = vsub(pos, traj_init.pos);
-      trajectory.shift = shift_pos;
-    } else {
-      trajectory.shift = vzero();
     }
-
-    result = plan_start_trajectory(&planner, &trajectory, data->reversed);
-    xSemaphoreGive(lockTraj);
   }
   return result;
 }
+
+int define_trajectory(const struct data_define_trajectory* data)
+{
+  if (data->trajectoryId >= NUM_TRAJECTORY_DEFINITIONS) {
+    return ENOEXEC;
+  }
+  trajectory_descriptions[data->trajectoryId] = data->description;
+  return 0;
+}