An Air India flight was forced to make an emergency landing soon after taking off from Delhi’s Indira Gandhi International Airport on Monday after two engineers “forgot” to remove pins from the landing gear of the flight, reported PTI. Both engineers were taken off duty pending inquiry, the airline’s spokesperson said.

The pins on the landing gear ensure that the wheels of an aircraft do not accidentally retract when it touches the ground. If the pins are not removed before take-off, the wheels cannot be retracted while the plane is in flight.

The Cochin-bound AI 993 plane took off from the airport at 5.36 am on Monday morning. However, one the pilot realised he was unable to retract the wheels, the flight was forced to make an emergency landing. The flight with 236 passengers on board, took off once again four hours later, at 9.56 am. The matter has been reported to the Directorate General of Civil Aviation.