Deflate the air mattress completely. Roll the mattress to make sure all the air has been released, then unroll it and lay it on a flat surface. Make sure you can clearly see the torn seam.
Apply a thick layer of adhesive sealant to the inside of the seam. Press the seam together and pinch each end with a clothespin. Angle the clothespins forty five degrees away from the center of the tear. The adhesive will leak outside the seam; this will not harm the seam or bed.
Apply another thin coat along the torn seam outside the bed. Align the new adhesive line to the seam to better hold the bed closed. Avoid gluing the clothespins to the seam as they will need to be removed.
Flatten the rest of the Aerobed and leave it overnight. Remove the clothespins in the morning and inflate the bed to check for cracks in the adhesive. Apply new adhesive to any cracks and let the adhesive rest for a full day or until it is completely dry.