Let docking angle be determined by the host building.

OpenRA.Mods.Common/Activities/Air/ReturnToBase.cs

@@ -111,9 +111,12 @@ namespace OpenRA.Mods.Common.Activities
 			if (ShouldLandAtBuilding(self, dest))
 			{
 				var exit = dest.FirstExitOrDefault();
-				var offset = exit != null ? exit.Info.SpawnOffset : WVec.Zero;
-				if (aircraft.Info.TurnToDock || !aircraft.Info.VTOL)
-					facing = aircraft.Info.InitialFacing;
+				var offset = WVec.Zero;
+				if (exit != null)
+				{
+					offset = exit.Info.SpawnOffset;
+					facing = exit.Info.Facing;
+				}
 
 				aircraft.MakeReservation(dest);
 				QueueChild(new Land(self, Target.FromActor(dest), offset, facing, Color.Green));

OpenRA.Mods.Common/Traits/Air/Aircraft.cs

@@ -114,9 +114,6 @@ namespace OpenRA.Mods.Common.Traits
 		[Desc("Does this VTOL actor need to turn before landing (on terrain)?")]
 		public readonly bool TurnToLand = false;
 
-		[Desc("Does this VTOL actor need to turn before landing on a resupplier?")]
-		public readonly bool TurnToDock = true;
-
 		[Desc("Does this actor automatically take off after resupplying?")]
 		public readonly bool TakeOffOnResupply = false;
 

OpenRA.Mods.Common/UpdateRules/Rules/RemoveTurnToDock.cs

@@ -0,0 +1,61 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version. For more
+ * information, see COPYING.
+ */
+#endregion
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace OpenRA.Mods.Common.UpdateRules.Rules
+{
+	public class RemoveTurnToDock : UpdateRule
+	{
+		public override string Name { get { return "TurnToDock is removed from the Aircraft trait."; } }
+		public override string Description
+		{
+			get
+			{
+				return "TurnToDock is removed from the Aircraft trait in favor of letting the Exit trait on the host" +
+					"building determine whether or not turning is required and to what facing the aircraft must turn.";
+			}
+		}
+
+		readonly List<Tuple<string, string>> turningAircraft = new List<Tuple<string, string>>();
+
+		public override IEnumerable<string> AfterUpdate(ModData modData)
+		{
+			var message = "TurnToDock is now deprecated. The following actors had TurnToDock enabled:\n"
+				+ UpdateUtils.FormatMessageList(turningAircraft.Select(n => n.Item1 + " (" + n.Item2 + ")"))
+				+ "\n If you wish these units to keep their turning behaviour when docking with a host building" +
+					"you will need to define a 'Facing' parameter on the 'Exit' trait of the host building. This change" +
+					"does not affect the behaviour for landing on terrain which is governed by TurnToLand.";
+
+			if (turningAircraft.Any())
+				yield return message;
+
+			turningAircraft.Clear();
+		}
+
+		public override IEnumerable<string> UpdateActorNode(ModData modData, MiniYamlNode actorNode)
+		{
+			var aircraft = actorNode.LastChildMatching("Aircraft");
+			if (aircraft != null)
+			{
+				var turnToDock = aircraft.LastChildMatching("TurnToDock");
+				if (turnToDock != null || turnToDock.NodeValue<bool>())
+					yield break;
+
+				turningAircraft.Add(Tuple.Create(actorNode.Key, actorNode.Location.Filename));
+			}
+
+			yield break;
+		}
+	}
+}

OpenRA.Mods.Common/UpdateRules/UpdatePath.cs

@@ -73,6 +73,7 @@ namespace OpenRA.Mods.Common.UpdateRules
 				new RenameSelfHealing(),
 				new ReplaceBurns(),
 				new RemoveMuzzleSplitFacings(),
+				new RemoveTurnToDock(),
 			})
 		};