diff --git a/nav.py b/nav.py
index 87e798f..4ed6603 100644
--- a/nav.py
+++ b/nav.py
@@ -64,6 +64,15 @@ def plan(destination):
     return route, total, total / CRUISE_SPEED, fuel
 
 
+def print_plan(destination):
+    """Print the flight plan for a destination."""
+    route, total, days, fuel = plan(destination)
+    print("Route: " + " -> ".join(NAMES[w] for w in route))
+    print(f"Distance: {total:.1f} million km")
+    print(f"Travel time: {round(days)} days")
+    print(f"Fuel required: {round(fuel)} t")
+
+
 def main():
     if sys.argv[1] == "--list":
         for key in sorted(ROUTES):
@@ -73,11 +82,7 @@ def main():
     if destination not in ROUTES:
         known = ", ".join(sorted(ROUTES))
         sys.exit(f"Unknown destination: {destination} (known: {known})")
-    route, total, days, fuel = plan(destination)
-    print("Route: " + " -> ".join(NAMES[w] for w in route))
-    print(f"Distance: {total:.1f} million km")
-    print(f"Travel time: {round(days)} days")
-    print(f"Fuel required: {round(fuel)} t")
+    print_plan(destination)
 
 
 if __name__ == "__main__":