Delhi: Crane, coupled with low visibility, posed problems on runway

In a letter to the NHAI on January 8, the Delhi International Airport Limited (DIAL) asked that the crane be lowered during low visibility hours. This was to be done by January 5. The letter noted that the cranes were re-erected two days later. When low visibility conditions hit flights over the past few days, DIAL was compelled to downgrade runway 3 from CAT-IIIB compliant to CAT-I compliant, said sources.

NHAI, in a response Monday, said, “Following aviation safety guidelines issued by Airports Authority of India. NHAI will not erect any cranes/booms in Package-1 of Dwarka Express-way from Shiv Murti Interchange till Road-Under-Bridge, thus stopping all construction activities at the site for this duration.”

According to DIAL sources, DGCA had sent the standard operation procedures for low visibility to the NHAI along with the letter, requesting the cranes be taken down from 8 pm to 10 am.

While take offs can still take place in low visibility conditions, it is near impossible for landings to take place due to the danger the cranes present. The 4th and newest runway, while operational, is still not CAT-IIIB compliant as the operational certification takes 42 to 45 days to be done. However, as per DIAL, calibration tests are complete.

What are CAT ops?

CAT operations are landing capabilities for flights in different weather conditions.

CAT I involves a decision height not dropping below 60 m (200ft) and a minimum visibility of 800m or a runway visual range of at least 550m.

CAT II entails a decision height between 30 m (100ft) and 60 m (200ft), and a runway visual range not less than 350 m.

CAT III is the most advanced, encompassing three subcategories. CAT IIIA has a decision height lower than 30 m (100ft) or none, and a runway visual range not less than 200 m.

CAT IIIB involves a decision height lower than 15 m (50ft) or none, and a runway visual range less than 200 m but not less than 50m.

Finally, CAT IIIC implies a precision instrument approach and landing with no decision height and no limitations on runway visual range.