diff --git a/src/openutm_verification/core/reporting/reporting.py b/src/openutm_verification/core/reporting/reporting.py
index a2a546ac..ea8c2cc5 100644
--- a/src/openutm_verification/core/reporting/reporting.py
+++ b/src/openutm_verification/core/reporting/reporting.py
@@ -10,7 +10,7 @@
 from loguru import logger
 
 from openutm_verification.core.execution.config_models import AppConfig, ReportingConfig
-from openutm_verification.core.flight_phase import FLIGHT_PHASE_LABELS
+from openutm_verification.core.flight_phase import FLIGHT_PHASE_LABELS, FlightPhase
 from openutm_verification.core.reporting._viz_engine import (
     extract_step_payload,
     label_from_step_id,
@@ -194,8 +194,22 @@ def _generate_html_report(report_data: ReportData, output_dir: Path, base_filena
         loader=FileSystemLoader(template_dir),
         autoescape=select_autoescape(enabled_extensions=("html", "xml"), default_for_string=True, default=True),
     )
+    _phase_rank: dict[str, int] = {p.value: i for i, p in enumerate(FlightPhase)}
+
+    def _phase_groupby(steps: list[dict]) -> list[tuple[str, list[dict]]]:
+        """Group steps by phase and return groups in canonical flight phase order."""
+        groups: dict[str, list[dict]] = {}
+        for step in steps:
+            phase = step.get("phase") or ""
+            groups.setdefault(phase, []).append(step)
+        return sorted(
+            groups.items(),
+            key=lambda item: _phase_rank.get(item[0], len(_phase_rank)),
+        )
+
     env.filters["markdown"] = lambda text: markdown.markdown(text) if text else ""
     env.filters["default_phase"] = lambda steps: [{**s, "phase": s.get("phase") or ""} for s in steps]
+    env.filters["phase_groupby"] = _phase_groupby
     template = env.get_template("report_template.html")
 
     html_content = template.render(
diff --git a/src/openutm_verification/core/templates/report_template.html b/src/openutm_verification/core/templates/report_template.html
index cfc34d48..67e730af 100644
--- a/src/openutm_verification/core/templates/report_template.html
+++ b/src/openutm_verification/core/templates/report_template.html
@@ -130,13 +130,13 @@ <h4>Documentation:</h4>
                 <h4>Steps:</h4>
                 {% set has_phases = result.steps | selectattr('phase') | list | length > 0 %}
                 {% if has_phases %}
-                    {% for phase_group in result.steps | default_phase | groupby('phase') %}
+                    {% for phase, steps in result.steps | default_phase | phase_groupby %}
                     {% set phase_index = loop.index %}
                     <div class="phase-group">
-                        {% if phase_group.grouper %}
+                        {% if phase %}
                         <div class="phase-header">
-                            <span class="phase-badge">{{ phase_group.grouper }}</span>
-                            {{ (phase_labels or {}).get(phase_group.grouper, phase_group.grouper) }}
+                            <span class="phase-badge">{{ phase }}</span>
+                            {{ (phase_labels or {}).get(phase, phase) }}
                         </div>
                         {% else %}
                         <div class="phase-header">Other Steps</div>
@@ -144,7 +144,7 @@ <h4>Steps:</h4>
                         <table class="steps-table">
                         <thead><tr><th>Step Name</th><th>Status</th><th>Duration (s)</th><th>Result</th></tr></thead>
                         <tbody>
-                        {% for step in phase_group.list %}
+                        {% for step in steps %}
                             {% set result_json = step.result | tojson(indent=2) %}
                             {% set line_count = result_json.split('\n') | length %}
                             <tr>
diff --git a/tests/test_reporting_output.py b/tests/test_reporting_output.py
index 14a35908..ddc1f802 100644
--- a/tests/test_reporting_output.py
+++ b/tests/test_reporting_output.py
@@ -139,6 +139,12 @@ def test_report_html_groups_steps_by_phase(tmp_path: Path):
     assert "Stream telemetry" in html
     assert "Cleanup" in html
 
+    # Phase headers must appear in canonical flight order: PRE FLIGHT -> CRUISE -> POST FLIGHT
+    pre_pos = html.index(">PRE FLIGHT<")
+    cruise_pos = html.index(">CRUISE<")
+    post_pos = html.index(">POST FLIGHT<")
+    assert pre_pos < cruise_pos < post_pos, "Phase groups must appear in canonical flight phase order"
+
 
 def test_report_html_no_phases_renders_flat_table(tmp_path: Path):
     app_config = _make_app_config(tmp_path)