The incident occurred earlier this week when the no-frill airline's Airbus A-320, coming in from Mumbai, had started descent for landing and its cockpit crew received a warning from an onboard system about the presence of another aircraft, sources said today.
The pilots aborted landing and had to 'go around' on the advise of the ATC, which caused panic among passengers, before safely touching down at the airport here.
The pilots "received an EGPWS (enhanced ground proximity warning systems) warning confirming about the helicopter in the same circuit," an IndiGo spokesperson said in New Delhi.
"As a precautionary measure, the IndiGo crew on board immediately informed the Air Traffic Control, which advised the captain to take a go around and then proceed for landing. In compliance with the ATC advisory, IndiGo flight 6E-433 made a normal landing at the Chandigarh Airport" on Tuesday.
A passenger Udeshpal Singh Uppal described it as a "traumatic" experience.
Satwant Singh Sandhu, a Punjab police official, said that as the plane suddenly started "zooming back into the air, I was among others who started screaming fearing that it would crash."
The matter was reported immediately to the aviation regulator DGCA, the airline spokesperson said, adding that "safety is our highest priority".
But Chandigarh airport director Capt H S Toor told PTI here today that "it was some sort of ignorance on the part of passengers as going around is a normal procedure."
"It's a 99 per cent go around case. Nothing was abnormal," he said, adding that in Delhi airport, such go-around procedures are carried out many a time as there are several landings.