Incorrect diagnosis of defects and lack of manpower to certify aircraft as fit before being released for flights are among the key causes identified by the Directorate General of Civil Aviation (DGCA) for the spurt in snags being reported by Indian carriers in recent weeks. An increasing trend of financially strained releasing aircraft under "minimum equipment list" (MEL). Under this, an aircraft is cleared to fly by allowing a non-critical component to be repaired or replaced within a certain time frame. This has been identified as the third major cause for the recent increase in mid-air scares. Accordingly, the regulator on Monday directed airlines to tackle these issues latest by July 28, failing which strict action will be taken.