Passengers were taken in four buses to board the aircraft.
After a Go First Airways flight took off from Bengaluru with more than 50 passengers forgotten in a bus on the tarmac, aviation regulator DGCA has asked the airline for a report.
The DGCA or Directorate General of Civil Aviation said today it is "looking into the matter" after many passengers slammed the airline on Twitter, calling it a "most horrifying experience".
Flight G8 116 took off for Delhi from Bengaluru's Kempegowda International Airport around 6.30 am on Monday.
Passengers were taken in four buses to the aircraft. Some 55 passengers kept waiting in one of the buses as the Go First plane took off, according to complaints on Twitter tagging the airline, Civil Aviation Minister Jyotiraditya Scindia, and Prime Minister Narendra Modi's office.
The passengers had their boarding passes and their bags were all checked in.
Go First Airways, responding to the tweets, said: "We regret the inconvenience caused."
The passengers were reportedly accommodated on a flight that left four hours later, around 10 am. "We have sought a report from the airline and appropriate action shall be taken," a DGCA official was quoted as saying by reports.
The airline, however, has not put out any statement on what appears to be a huge botch-up.
Sumit Kumar, who works for Autopact in Bengaluru, was among the passengers left waiting on the tarmac. "The passengers were given an alternative to take an Air India flight at 10:00 am," he said.
"We were more than 54 plus on the bus. The boarding wasn't completed. 6:20 am was the flight, and they put us in another flight at 10 am," he said.
According to Mr Kumar, their bus was left near the gate when the others offloaded passengers near the plane. "The ground staff was checking whether the flight took off. They said initially the flight will return. I missed my meetings. This is going to be my last flight on Go First," he told NDTV.
A post by Shreya Sinha called it the "most horrifying experience". She said the passengers were in the bus for an hour.
"Most horrifying experience with @GoFirstairways 5:35 am Boarded the bus for aircraft 6:30 am Still in bus stuffed with over 50 passengers, driver stopped the bus after being forced. Flight G8 116 takes off, leaving 50+ passengers. Heights of negligence!" tweeted Shreya Sinha.
Satish Kumar, whose Twitter bio says "youth BJP", shared a screenshot of the ticket.
"Flight G8 116 (BLR - DEL) flew leaving passengers on ground! More than 50 passengers on 1 bus were left on ground and the flight took off with just passengers of 1 bus onboarded. Is @GoFirstairways@JM_Scindia @PMOIndia operating in sleep? No Basic checks."
In recent weeks, airlines have faced scrutiny over a range of infractions, keeping the regulator busy with inquiries. The pilots and crew of an Air India flight from New York to Delhi on November 26 have been grounded over their handling of a drunk business class passenger urinating on a 70-year-old woman.
The passenger has been arrested after more than six weeks. Air India, which complained to the police only last week, admitted lapses.
Instances of fights on flights have also emerged.