Dim SearchCell As Range
Dim SearchTerm As Variant
Sheets("Air").Select
Range("A3").Select
Do
SearchTerm = ActiveCell.Value
Sheets("Mixed").Select
Columns("A").Select
Set SearchCell = Cells.Find(What:=SearchTerm)

If SearchCell Is Nothing Then
    Sheets("Air").Select
    ActiveCell.Offset(1, 0).Select
Else
    Cells.Find(What:=SearchTerm).Activate
    ActiveCell.EntireRow.Select
    Selection.Delete Shift:=xlUp
    Sheets("Air").Select
    ActiveCell.Offset(1, 0).Select
End If

Loop Until ActiveCell.Value = ""