The Southwest Airlines team has detected small, subsurface cracks in three of its jetliners. The cracks are similar to those found in the Boeing 737-300, which caused the aircraft to lose pressure and forcing a terrifying emergency landing. 

The Southwest airlines said that the planes which have cracks similar to those in the Boeing 737-300 would be evaluated and repaired before they are return to service. The cracks found in the three planes were developed in two lines of riveted joints that run the length of the aircraft. The riveted joints that run the length of the plane were previously not believed to be cause of technical problem but now the airline is testing them.

The airlines have planned to examine 79 other Boeing 737-300s grounded by it. The other 19 aircrafts inspected by the Southwest Airlines has shown no technical problems and will be returned to service. Evaluation of the remaining airplanes is expected to be completed by Tuesday.

About 600 flights were cancelled by the weekend after Southwest grounded 79 of its planes.  The airlines have said that the flight cancellation is likely to continue until the planes are back in service.