A major aviation crash was avoided on Wednesday as an alert woman pilot saved the lives of 300 passengers when one Vistara flight entered an active runway just as another Vistara Airlines plane was taking off at the Delhi airport.

India's aviation regulator, the Directorate General of Civil Aviation (DGCA), said this happened owing to a failure by Air Traffic Control (ATC).

An Ahmedabad-Delhi flight of Vistara Airlines had just landed and had been instructed by an ATC official to cross an active runway to reach the parking bay.

Meanwhile, a Vistara Airlines Delhi-Bagdogra flight had been given permission to take off on that same runway.

The collision was only avoided thanks to 45-year-old Captain Sonu Gill on the Ahmedabad-Delhi flight.

According to reports, the planes were 1.8 km, or 1,800 metres, apart, and if the pilot had not warned ATC of the presence of the other plane, the outcome could have been disastrous.

The DGCA said that Vistara flight VTI926 had landed on Runway 29L and was told by ATC to cross Runway 29R en route to its parking bay. However, the ATC official 'momentarily forgot' the instructions given to VTI926 and told flight VTI725 to take off from Runway 29R.

The regulator's statement said the ATC 'on realisation of the error, based on input from VTI926, tower controller instructed VTI725 to cancel take-off'.

The aviation regulator said an 'alert pilot in the aircraft crossing the runway (VTI926) alerted Air Traffic Control and the aircraft on its take-off run (VTI725) was ordered to abort take-off'.