diff --git a/src/tasks/simulation.rs b/src/tasks/simulation.rs
index 27f5052..a20c54b 100644
--- a/src/tasks/simulation.rs
+++ b/src/tasks/simulation.rs
@@ -11,7 +11,7 @@ use nalgebra::{Vector2, Vector3};
 use log::*;
 use rmp::decode::{RmpRead, RmpReadErr, ValueReadError};
 
-use crate::{events::{Measurement, SensorSource, SensorState}, simdata::{AnnotationReading, EventRecord, EventStreamHeader, GPSReading, IMUReading, RmpData, SimDataError, StreamEvent, StreamHeader, StreamIndex, StreamType}};
+use crate::{Breaker, events::{Measurement, SensorSource, SensorState}, simdata::{AnnotationReading, EventRecord, EventStreamHeader, GPSReading, IMUReading, RmpData, SimDataError, StreamEvent, StreamHeader, StreamIndex, StreamType}};
 
 #[derive(Debug)]
 pub struct SharedFlash<S> {
@@ -99,24 +99,28 @@ impl<S: ReadStorage + Clone + core::fmt::Debug> Iterator for SimDataTable<S> whe
                     Ok(header) => {
                         match self.reader.subset(header.size) {
                             Ok(sensor_reader) => {
-                                self.reader.seek(header.size);
+                                self.reader.seek(header.size).unwrap_or_else(|err| {
+                                    error!("Simulation data appears bigger than the storage capacity: {err:?}")
+                                });
                                 self.index += 1;
                                 debug!("Found header={header:?}");
                                 return Some(SimDataReader::open(sensor_reader, header.id));
                             },
                             err => {
-                                error!("Read error while opening simulation stream {err:?}");
+                                error!("Could not open the next simulation data chunk: {err:?}");
                                 return None;
                             }
                         }
                     },
                     Err(SimDataError::UnsupportedStreamType(meta)) => {
                         error!("Found unknown simulation data chunk {meta:?}");
-                        self.reader.seek(meta.size as usize);
+                        self.reader.seek(meta.size as usize).unwrap_or_else(|err| {
+                            error!("Simulation data appears bigger than the storage capacity: {err:?}")
+                        });
                         self.index += 1;
                     }
                     Err(err) => {
-                        error!("Read error while decoding simulation stream table {err:?}");
+                        error!("Read error while reading next chunk in simulation stream table {err:?}");
                         return None;
                     }
                 }
@@ -145,13 +149,18 @@ impl<S: ReadStorage> RangeReader<S> {
         }
     }
 
-    pub fn seek(&mut self, offset: usize) {
+    pub fn seek(&mut self, offset: usize) -> Result<(), RangeReadError<S::Error>> {
         self.offset += offset;
+        if self.offset > self.end {
+            Err(RangeReadError::OutOfData)
+        } else {
+            Ok(())
+        }
     }
 
     pub fn subset(&self, size: usize) -> Result<Self, SimDataError<S::Error>> where S: Clone + core::fmt::Debug {
         trace!("subset {:#02x}:{:#02x} -> {:#02x}:{:#02x}", self.start, self.end, self.start + self.offset, self.start + self.offset + size);
-        if self.start + self.offset + size < self.end {
+        if self.start + self.offset + size > self.end {
             Err(SimDataError::EndOfStream)
         } else {
             Ok(Self {
@@ -276,10 +285,21 @@ pub async fn simulation_task(mut reader: SimDataReader<SharedFlash<FlashStorage>
     events.send(Measurement::SensorHardwareStatus(SensorSource::Simulation, SensorState::AcquiringFix)).await;
     events.send(Measurement::SensorHardwareStatus(reader.srcid(), SensorState::Online)).await;
 
+    let mut idx = 0;
+    let mut idx_breaker = Breaker::default();
+
     // TODO: SimulationProgress updates
     loop {
         match reader.read_next().await {
-            Ok(Some(next_evt)) => events.send(next_evt).await,
+            Ok(Some(next_evt)) => {
+                events.send(next_evt).await;
+                let pct = (idx as f32) / (reader.event_count as f32);
+                idx_breaker.set((pct * 255.0) as u8);
+                if let Some(pct) = idx_breaker.read_tripped() {
+                    events.send(Measurement::SimulationProgress(reader.srcid(), reader.runtime, pct)).await;
+                }
+                idx += 1;
+            },
             Ok(None) => {
                 warn!("End of simulation data stream");
                 break