(This story originally appeared in on Jul 25, 2017)

NEW DELHI: Air India has grounded two pilots who forgot to retract aircraft landing gear after take off and then flew all the way from Kolkata to Nagpur with the wheels out. While the flight's destination was Mumbai, flying with the wheels out meant flying low and more fuel burn due to which the plane had to land at Nagpur after running low on fuel.The pilots realised that the wheels had been out all the while only while preparing to land at Nagpur! The lapse happened on AI 676 that took off from Kolkata last Saturday (July 22) with 99 Mumbai-bound passengers on board."After take off, both the women pilots forgot to retract the landing gear. As a result, the brand new Airbus A-320 continued to ascend at a very low climb rate. The plane finally gave up climbing after reaching an altitude of 24,000 feet as the extended landing gear meant very heavy drag. It then levelled out (continued flying at 24,000 feet as opposed to the usually assigned level of 35-37,000 feet) and flew at 230 knots (426 kmph) for the next 1.5 hours," said a source.Aircraft are designed to fly with minimum drag for enhanced fuel efficiency and extended range. Since AI 676 was flying at a much lower than the optimal level and that too with wheels out, it meant more fuel burn due to extra drag.By the time the A-320 was near Nagpur, it was very low on fuel and the pilots decided to divert there as the plane could not have made it to Mumbai. "When preparing to land, they decided to lower the landing gear. At this point they realised that the wheels had been out all the while from Kolkata!" said the source.AI spokesperson Dhananjay Kumar said the airline is investigating this case. "The pilots were de-rostered (taken off flying duty) after the incident was reported," Kumar said.Expressing disbelief at this lapse, a senior AI pilot attributed this to "human error and/or casual approach"."This lapse shows extremely poor situational awareness and complete breakdown of crew resource management between both women pilots on that flight. The post-take off check list includes checking if the landing gear has been retracted. They realised the landing gears were down only while preparing to land at Nagpur after running low on fuel. In such poor situational awareness, it is a miracle that they realised the plane is running low on fuel," said a senior commander.Pilots are also surprised why and how the cabin crew or passengers did not complain of noise and vibrations associated with flying at lower altitudes. They may have felt flying in monsoon means more turbulence than usual, said a pilot. Flying at higher altitudes where air is less dense leads to improved jet engine efficiency, which translates into less fuel burn.