diff --git a/app/Cron/Nightly/ClearExpiredSimbrief.php b/app/Cron/Hourly/ClearExpiredSimbrief.php
similarity index 74%
rename from app/Cron/Nightly/ClearExpiredSimbrief.php
rename to app/Cron/Hourly/ClearExpiredSimbrief.php
index 37925fe6..8a770bb6 100644
--- a/app/Cron/Nightly/ClearExpiredSimbrief.php
+++ b/app/Cron/Hourly/ClearExpiredSimbrief.php
@@ -1,9 +1,9 @@
 <?php
 
-namespace App\Cron\Nightly;
+namespace App\Cron\Hourly;
 
 use App\Contracts\Listener;
-use App\Events\CronNightly;
+use App\Events\CronHourly;
 use App\Services\SimBriefService;
 use Illuminate\Support\Facades\Log;
 
@@ -22,9 +22,9 @@ class ClearExpiredSimbrief extends Listener
     /**
      * @param \App\Events\CronNightly $event
      */
-    public function handle(CronNightly $event): void
+    public function handle(CronHourly $event): void
     {
-        Log::info('Nightly: Removing expired Simbrief entries');
+        Log::info('Hourly: Removing expired Simbrief entries');
         $this->simbriefSvc->removeExpiredEntries();
     }
 }
diff --git a/app/Database/migrations/2021_05_28_165608_remove_setting_simbriefexpiredays.php b/app/Database/migrations/2021_05_28_165608_remove_setting_simbriefexpiredays.php
new file mode 100644
index 00000000..f8106998
--- /dev/null
+++ b/app/Database/migrations/2021_05_28_165608_remove_setting_simbriefexpiredays.php
@@ -0,0 +1,19 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Support\Facades\DB;
+
+class RemoveSettingSimbriefExpireDays extends Migration
+{
+    /**
+     * Run the migrations.
+     *
+     * @return void
+     */
+    public function up()
+    {
+        DB::table('settings')
+            ->where(['key' => 'simbrief.expire_days'])
+            ->delete();
+    }
+}
diff --git a/app/Database/seeds/settings.yml b/app/Database/seeds/settings.yml
index e353a517..b2478394 100644
--- a/app/Database/seeds/settings.yml
+++ b/app/Database/seeds/settings.yml
@@ -207,13 +207,13 @@
   options: ''
   type: boolean
   description: 'Only allow briefs to be created for bidded flights'
-- key: simbrief.expire_days
+- key: simbrief.expire_hours
   name: 'Simbrief Expire Time'
   group: simbrief
-  value: 5
+  value: 6
   options: ''
   type: number
-  description: 'Days after how long to remove unused briefs'
+  description: 'Hours after how long to remove unused briefs'
 - key: simbrief.noncharter_pax_weight
   name: 'Non-Charter Passenger Weight'
   group: simbrief
@@ -256,6 +256,13 @@
   options: ''
   type: boolean
   description: 'Use privatized user name as SimBrief OFP captain name'
+- key: simbrief.block_aircraft
+  name: 'Restrict Aircraft'
+  group: simbrief
+  value: false
+  options: ''
+  type: boolean
+  description: 'When enabled, an aircraft can only be used for one active SimBrief OFP and Flight/Pirep'
 - key: pireps.duplicate_check_time
   name: 'PIREP duplicate time check'
   group: pireps
diff --git a/app/Http/Controllers/Frontend/PirepController.php b/app/Http/Controllers/Frontend/PirepController.php
index 3759ac05..00697cef 100644
--- a/app/Http/Controllers/Frontend/PirepController.php
+++ b/app/Http/Controllers/Frontend/PirepController.php
@@ -399,7 +399,13 @@ class PirepController extends Controller
             if ($brief !== null) {
                 /** @var SimBriefService $sbSvc */
                 $sbSvc = app(SimBriefService::class);
-                $sbSvc->attachSimbriefToPirep($pirep, $brief);
+                // Keep the flight_id with SimBrief depending on the button selected
+                // Save = Keep the flight_id , Submit = Remove the flight_id
+                if ($attrs['submit'] === 'save') {
+                    $sbSvc->attachSimbriefToPirep($pirep, $brief, true);
+                } elseif ($attrs['submit'] === 'submit') {
+                    $sbSvc->attachSimbriefToPirep($pirep, $brief);
+                }
             }
         }
 
diff --git a/app/Http/Controllers/Frontend/SimBriefController.php b/app/Http/Controllers/Frontend/SimBriefController.php
index 32497d1d..f91629b6 100644
--- a/app/Http/Controllers/Frontend/SimBriefController.php
+++ b/app/Http/Controllers/Frontend/SimBriefController.php
@@ -100,6 +100,13 @@ class SimBriefController
                 $aircrafts = $aircrafts->where('airport_id', $flight->dpt_airport_id);
             }
 
+            if (setting('simbrief.block_aircraft')) {
+                // Build a list of aircraft_id's being used for active sb packs
+                $sb_aircraft = SimBrief::whereNotNull('flight_id')->pluck('aircraft_id');
+                // Filter aircraft list to non used/blocked ones
+                $aircrafts = $aircrafts->whereNotIn('id', $sb_aircraft);
+            }
+
             return view('flights.simbrief_aircraft', [
                 'flight'    => $flight,
                 'aircrafts' => $aircrafts,
diff --git a/app/Providers/CronServiceProvider.php b/app/Providers/CronServiceProvider.php
index af3934ce..0d97f546 100644
--- a/app/Providers/CronServiceProvider.php
+++ b/app/Providers/CronServiceProvider.php
@@ -2,11 +2,11 @@
 
 namespace App\Providers;
 
+use App\Cron\Hourly\ClearExpiredSimbrief;
 use App\Cron\Hourly\DeletePireps;
 use App\Cron\Hourly\RemoveExpiredBids;
 use App\Cron\Hourly\RemoveExpiredLiveFlights;
 use App\Cron\Nightly\ApplyExpenses;
-use App\Cron\Nightly\ClearExpiredSimbrief;
 use App\Cron\Nightly\NewVersionCheck;
 use App\Cron\Nightly\PilotLeave;
 use App\Cron\Nightly\RecalculateBalances;
@@ -31,7 +31,6 @@ class CronServiceProvider extends ServiceProvider
             SetActiveFlights::class,
             RecalculateStats::class,
             NewVersionCheck::class,
-            ClearExpiredSimbrief::class,
         ],
 
         CronWeekly::class => [
@@ -45,6 +44,7 @@ class CronServiceProvider extends ServiceProvider
             DeletePireps::class,
             RemoveExpiredBids::class,
             RemoveExpiredLiveFlights::class,
+            ClearExpiredSimbrief::class,
         ],
     ];
 }
diff --git a/app/Services/PirepService.php b/app/Services/PirepService.php
index e43b680e..1696645c 100644
--- a/app/Services/PirepService.php
+++ b/app/Services/PirepService.php
@@ -148,6 +148,18 @@ class PirepService extends Service
             throw new AircraftNotAvailable($pirep->aircraft);
         }
 
+        // See if this aircraft is being used by another user's active simbrief ofp
+        if (setting('simbrief.block_aircraft', false)) {
+            $sb_aircraft = SimBrief::select('aircraft_id')
+                ->where('aircraft_id', $pirep->aircraft_id)
+                ->where('user_id', '!=', $pirep->user_id)
+                ->whereNotNull('flight_id')
+                ->count();
+            if ($sb_aircraft > 0) {
+                throw new AircraftNotAvailable($pirep->aircraft);
+            }
+        }
+
         // See if this aircraft is at the departure airport
         /* @noinspection NotOptimalIfConditionsInspection */
         if (setting('pireps.only_aircraft_at_dpt_airport') && $aircraft->airport_id !== $pirep->dpt_airport_id) {
@@ -164,9 +176,20 @@ class PirepService extends Service
             }
         }
 
-        event(new PirepPrefiled($pirep));
-
         $pirep->save();
+        $pirep->refresh();
+
+        // Check if there is a simbrief_id, update it to have the pirep_id
+        // Keep the flight_id until the end of flight (pirep file)
+        if (array_key_exists('simbrief_id', $attrs)) {
+            /** @var SimBrief $simbrief */
+            $simbrief = SimBrief::find($attrs['simbrief_id']);
+            if ($simbrief) {
+                $this->simBriefSvc->attachSimbriefToPirep($pirep, $simbrief, true);
+            }
+        }
+
+        event(new PirepPrefiled($pirep));
 
         return $pirep;
     }
@@ -427,6 +450,19 @@ class PirepService extends Service
             }
         }
 
+        // Check if there is a simbrief_id, change it to be set to the PIREP
+        // at the end of the flight when it's been submitted finally.
+        // Prefile, Save (as draft) and File already have this but the Submit button
+        // visible at pireps.show blade uses this function so Simbrief also needs to
+        // checked here too (to remove the flight_id and release the aircraft)
+        if (!empty($pirep->simbrief)) {
+            /** @var SimBrief $simbrief */
+            $simbrief = SimBrief::find($pirep->simbrief->id);
+            if ($simbrief) {
+                $this->simBriefSvc->attachSimbriefToPirep($pirep, $simbrief);
+            }
+        }
+
         Log::info('New PIREP filed', [$pirep]);
         event(new PirepFiled($pirep));
 
diff --git a/app/Services/SimBriefService.php b/app/Services/SimBriefService.php
index f09880c5..3ccc2a87 100644
--- a/app/Services/SimBriefService.php
+++ b/app/Services/SimBriefService.php
@@ -132,21 +132,23 @@ class SimBriefService extends Service
      *
      * 1. Read from the XML the basic PIREP info (dep, arr), and then associate the PIREP
      *    to the flight ID
-     * 2. Remove the flight ID from the SimBrief field and assign the pirep_id to the row
+     * 2. Remove the flight ID from the SimBrief model and assign the pirep ID to the row
+     *    at the end of the flight. Keep flight ID until the flight ends (pirep file).
      * 3. Update the planned flight route in the acars table
      * 4. Add additional flight fields (ones which match ACARS)
      *
      * @param          $pirep
-     * @param SimBrief $simBrief The briefing to create the PIREP from
+     * @param SimBrief $simBrief    The briefing to create the PIREP from
+     * @param bool     $keep_flight True keeps the flight_id, default is false
      *
      * @return \App\Models\Pirep
      */
-    public function attachSimbriefToPirep($pirep, SimBrief $simBrief): Pirep
+    public function attachSimbriefToPirep($pirep, SimBrief $simBrief, $keep_flight = false): Pirep
     {
         $this->addRouteToPirep($pirep, $simBrief);
 
         $simBrief->pirep_id = $pirep->id;
-        $simBrief->flight_id = null;
+        $simBrief->flight_id = !empty($keep_flight) ? $pirep->flight_id : null;
         $simBrief->save();
 
         return $pirep;
@@ -185,14 +187,14 @@ class SimBriefService extends Service
     }
 
     /**
-     * Remove any expired entries from the SimBrief table. Expired means there's
-     * a flight_id attached to it, but no pirep_id (meaning it was never used for
-     * an actual flight)
+     * Remove any expired entries from the SimBrief table.
+     * Expired means there's a flight_id attached to it, but no pirep_id
+     * (meaning it was never used for an actual flight)
      */
     public function removeExpiredEntries(): void
     {
-        $expire_days = setting('simbrief.expire_days', 5);
-        $expire_time = Carbon::now('UTC')->subDays($expire_days);
+        $expire_hours = setting('simbrief.expire_hours', 6);
+        $expire_time = Carbon::now('UTC')->subHours($expire_hours);
 
         $briefs = SimBrief::where([
             ['pirep_id', null],
@@ -202,7 +204,7 @@ class SimBriefService extends Service
         foreach ($briefs as $brief) {
             $brief->delete();
 
-            // TODO: Delete any assets
+            // TODO: Delete any assets (Which assets ?)
         }
     }
 }