diff --git a/src/newgrf_airport.cpp b/src/newgrf_airport.cpp
--- a/src/newgrf_airport.cpp
+++ b/src/newgrf_airport.cpp
@@ -21,7 +21,8 @@ AirportSpec AirportSpec::oilrig = {NULL,
 AirportSpec AirportSpec::specs[NUM_AIRPORTS];
 
 /**
- * Retrieve airport spec for the given airport
+ * Retrieve airport spec for the given airport. If an override is available
+ *  it is returned.
  * @param type index of airport
  * @return A pointer to the corresponding AirportSpec
  */
@@ -32,6 +33,19 @@ AirportSpec AirportSpec::specs[NUM_AIRPO
 	return &AirportSpec::specs[type];
 }
 
+/**
+ * Retrieve airport spec for the given airport. Even if an override is
+ *  available the base spec is returned.
+ * @param type index of airport
+ * @return A pointer to the corresponding AirportSpec
+ */
+/* static */ AirportSpec *AirportSpec::GetWithoutOverride(byte type)
+{
+	if (type == AT_OILRIG) return &oilrig;
+	assert(type < lengthof(AirportSpec::specs));
+	return &AirportSpec::specs[type];
+}
+
 bool AirportSpec::IsAvailable() const
 {
 	if (_cur_year < this->min_year) return false;
diff --git a/src/newgrf_airport.h b/src/newgrf_airport.h
--- a/src/newgrf_airport.h
+++ b/src/newgrf_airport.h
@@ -47,6 +47,7 @@ struct AirportSpec {
 	TTDPAirportType ttd_airport_type;      ///< ttdpatch airport type (Small/Large/Helipad/Oilrig)
 
 	static const AirportSpec *Get(byte type);
+	static AirportSpec *GetWithoutOverride(byte type);
 
 	bool IsAvailable() const;