One suction unit. An untested suction unit. A Yankauer as the primary catheter.
Laryngoscoping before decontaminating — or suctioning endlessly without the blade in.
Trying to pass a bougie through a standard suction catheter.
Working the suction and the laryngoscope alone when there is a second pair of hands in the room.
Parking deep when the blood is coming down from the face.
Never let this delay a cricothyrotomy in a patient you cannot oxygenate.