Depth of the ETT in the trachea will be determined by advancing the bronchoscope to just touch the carina, and the depth at the elbow connector marked with a spring clip applied to the bronchoscope. It will then be withdrawn to the ETT tip, and a second clip placed. The bronchoscope will be withdrawn further until the light glowing transmitted from the bronchoscope tip shines through the cricothyroid membrane, and a third clip placed on the bronchoscope. The bronchoscope will be removed and surgery will proceed. Measurements will be made of the distance between the clips.