diff --git a/OpenRA.Mods.Common/Activities/Air/TakeOff.cs b/OpenRA.Mods.Common/Activities/Air/TakeOff.cs
index deed92cfb8..2ed1d5a5ab 100644
--- a/OpenRA.Mods.Common/Activities/Air/TakeOff.cs
+++ b/OpenRA.Mods.Common/Activities/Air/TakeOff.cs
@@ -28,7 +28,7 @@ namespace OpenRA.Mods.Common.Activities
 			if (aircraft.ForceLanding)
 				return;
 
-			if (self.World.Map.DistanceAboveTerrain(aircraft.CenterPosition).Length >= aircraft.Info.MinAirborneAltitude)
+			if (!aircraft.HasInfluence())
 				return;
 
 			// We are taking off, so remove influence in ground cells.
diff --git a/OpenRA.Mods.Common/Activities/DeliverUnit.cs b/OpenRA.Mods.Common/Activities/DeliverUnit.cs
index 8a67675c29..cf10bed5e6 100644
--- a/OpenRA.Mods.Common/Activities/DeliverUnit.cs
+++ b/OpenRA.Mods.Common/Activities/DeliverUnit.cs
@@ -86,8 +86,6 @@ namespace OpenRA.Mods.Common.Activities
 				if (carryall.Carryable == null)
 					return;
 
-				self.Trait<Aircraft>().RemoveInfluence();
-
 				var localOffset = carryall.CarryableOffset.Rotate(body.QuantizeOrientation(self.Orientation));
 				var targetPosition = self.CenterPosition + body.LocalToWorld(localOffset);
 				var targetLocation = self.World.Map.CellContaining(targetPosition);
diff --git a/OpenRA.Mods.Common/Traits/Air/Aircraft.cs b/OpenRA.Mods.Common/Traits/Air/Aircraft.cs
index a27962f0d1..f2318dfecb 100644
--- a/OpenRA.Mods.Common/Traits/Air/Aircraft.cs
+++ b/OpenRA.Mods.Common/Traits/Air/Aircraft.cs
@@ -622,7 +622,7 @@ namespace OpenRA.Mods.Common.Traits
 
 		public (CPos Cell, SubCell SubCell)[] OccupiedCells()
 		{
-			if (!self.IsAtGroundLevel())
+			if (self.World.Map.DistanceAboveTerrain(CenterPosition).Length >= Info.MinAirborneAltitude)
 				return landingCells.Select(c => (c, SubCell.FullCell)).ToArray();
 
 			return new[] { (TopLeft, SubCell.FullCell) };
@@ -869,6 +869,10 @@ namespace OpenRA.Mods.Common.Traits
 
 		public void AddInfluence(IEnumerable<CPos> landingCells)
 		{
+			if (this.landingCells.Any())
+				throw new InvalidOperationException(
+					$"Cannot {nameof(AddInfluence)} until previous influence is removed with {nameof(RemoveInfluence)}");
+
 			this.landingCells = landingCells;
 			if (self.IsInWorld)
 				self.World.ActorMap.AddInfluence(self, this);
@@ -876,9 +880,7 @@ namespace OpenRA.Mods.Common.Traits
 
 		public void AddInfluence(CPos landingCell)
 		{
-			landingCells = new List<CPos> { landingCell };
-			if (self.IsInWorld)
-				self.World.ActorMap.AddInfluence(self, this);
+			AddInfluence(new[] { landingCell });
 		}
 
 		public void RemoveInfluence()
@@ -889,6 +891,11 @@ namespace OpenRA.Mods.Common.Traits
 			landingCells = Enumerable.Empty<CPos>();
 		}
 
+		public bool HasInfluence()
+		{
+			return landingCells.Any() || self.World.Map.DistanceAboveTerrain(CenterPosition).Length < Info.MinAirborneAltitude;
+		}
+
 		#endregion
 
 		#region Implement IMove
diff --git a/OpenRA.Mods.Common/Traits/World/ActorMap.cs b/OpenRA.Mods.Common/Traits/World/ActorMap.cs
index e55bd3d432..b9b2c68d69 100644
--- a/OpenRA.Mods.Common/Traits/World/ActorMap.cs
+++ b/OpenRA.Mods.Common/Traits/World/ActorMap.cs
@@ -248,8 +248,7 @@ namespace OpenRA.Mods.Common.Traits
 				{
 					current = node.Actor;
 					node = node.Next;
-					if (!current.Disposed)
-						return true;
+					return true;
 				}
 
 				return false;
@@ -284,7 +283,7 @@ namespace OpenRA.Mods.Common.Traits
 
 			var always = sub == SubCell.FullCell || sub == SubCell.Any;
 			for (var i = layer[uv]; i != null; i = i.Next)
-				if (!i.Actor.Disposed && (i.SubCell == sub || i.SubCell == SubCell.FullCell || always))
+				if (i.SubCell == sub || i.SubCell == SubCell.FullCell || always)
 					yield return i.Actor;
 		}
 
@@ -386,7 +385,7 @@ namespace OpenRA.Mods.Common.Traits
 		{
 			var always = sub == SubCell.FullCell || sub == SubCell.Any;
 			for (var i = layer[uv]; i != null; i = i.Next)
-				if ((always || i.SubCell == sub || i.SubCell == SubCell.FullCell) && !i.Actor.Disposed && withCondition(i.Actor))
+				if ((always || i.SubCell == sub || i.SubCell == SubCell.FullCell) && withCondition(i.Actor))
 					return true;
 
 			return false;