Aviation regulator DGCA on Thursday permitted two Vistara pilots, who had issued a 'Mayday' distress call due to low-fuel near Lucknow airport while operating a Mumbai-Delhi flight, to resume their duties till the final investigation report comes in, sources said.
"Both the pilots have been permitted by the DGCA to resume their flying duties. However, the final decision regarding them would be taken once the final investigation report comes in," a source told PTI.
The pilots, who were operating the UK944 flight, were grounded by the DGCA on Tuesday, a day after they issued the distress call.
The preliminary enquiry by the Directorate General of Civil Aviation (DGCA) showed that when the pilots were approaching Delhi airport's runway 29, at a height of 250 feet, the pilot-in-command decided to divert to Lucknow due to "perceived increase in tail winds beyond the aircraft limitations", source said.
The plane had 3,396 kg of estimated fuel on board (EFOB) when the pilot-in-command took this decision, the sources said .
The pilots - who were approaching for landing and were just 17 miles from runway 27 of Lucknow airport - were informed by the Air Traffic Control (ATC) of the airport that the runway visual range (RVR) is 475 metres and it is dropping to 275 metres, according to the enquiry.
The minimum RVR required for landing safely is 600 metres.
The preliminary enquiry of the DGCA found that due to low visibility, the pilots discontinued the approach towards landing and their aircraft was cleared by the ATC to climb to 4,000 feet, the sources said.
When the EFOB reached 1260 kgs, the 'minimum fuel' was declared and when it was 1100 kgs, the pilots issued a 'Mayday Fuel' call, they said.
The pilot-in-command must declare a situation of fuel emergency by broadcasting "Mayday Mayday Mayday Fuel", when the calculated usable fuel estimated to be available upon landing at the nearest airport -- where a safe landing can be made -- is less than the planned final reserve fuel, as per DGCA rules.
The pilots then asked the ATC to inform them about the closest available airport, the sources said.
The two, meanwhile, discussed the options for diversion and decided to divert to Kanpur. Due to weather observed enroute, the pilots further decided to divert to Allahabad, they said.
At this time, the ATC informed them that the weather in Lucknow was improving and the RVR had reached 600 metres, according to the preliminary enquiry.
"Just a few seconds later, the ATC informed that the RVR was 1000 metres. At this point, the plane was 37 miles from Lucknow airport and 58 miles from Allahabad airport. The fuel in the plane was just 500 kgs," the enquiry found.
The pilots decided to go to Lucknow airport as the distance was less, the sources said.
When the aircraft landed at Lucknow airport, the plane had just 260 kgs of EFOB, they said.