Flight delays increase with heavy rain

MUMBAI: Though the percentage of on-time departures for morning flights has gone up at the city airport as the new norms for mitigating flight delays were implemented early this week, on Thursday, with heavy rain, delays increased.

"The delays went up a bit today due to rain but we don't have the figures as of now," said M G Junghare, general manager, Mumbai airport, adding that airlines have wizened up to the new norms. "If an arrival is late and the aircraft cannot operate the next departure on time, the airline flies with a revised time of departure. So it gets a revised slot before passengers board the aircraft," he added. Technically, such a flight, which has a revised time of departure would not be recorded as having operated on time.

"Following a delayed arrival or departure, we reschedule all the other flights of the particular aircraft," said an airline official. Whether the passengers of the consequent flights get informed about the delay before they leave for the airport depends on how early the information comes in, he added.

Getting the morning departures in order was a priority for air traffic control, which started implementing DGCA's Air Transport Circular 10 of 2009, from Monday onwards to mitigate flight delays. Domestic flight arrivals at Mumbai airport start only after 7.30 am. But there are a total of 37 departures between 5.50 am and 7 am itself, bunched together in nine slots (see box). "Each departure takes three minutes. Thirty-seven departures means a minimum of 81 minutes. But the flight schedules listed demand that these 37 departures be operated in 70 minutes," added Junghare. It is in this one critical hour that delays creep into flight schedules and send a cascading effect on departure timings. The 15 flights scheduled between 5.40 am and 6 am, always depart between 6 am and 7 am, bunching flights further.

However, air traffic controllers have managed to overcome that in the last two days, despite a shutdown of operations on the secondary runway. "By having a minute-to-minute co-ordination with Approach Control, we managed to space the departures in that one critical hour and check delays to a great extent," said Junghare.