A Frontier Airlines Airbus A321-200 aircraft nearly took off from Nashville International Airport with an ice-covered wing during last month’s snow/ice storm.

The aircraft had gone through de-icing, but a flight attendant indicated they needed to return to the gate due to their left wing not being de-iced.

The Federal Aviation Administration is investigating the incident, which could have caused problems during takeoff and created an unsafe situation for passengers and crew.

The aircraft had reportedly gone through a de-icing process, but the company responsible somehow failed to de-ice the wing.

Frontier Airlines confirmed the incident and added that it is no longer working with the de-icing company that performed the job.

“Safety is our foremost priority and we are very proud of our flight crew for identifying the issue and ensuring the matter was addressed before takeoff,” Frontier said in a statement. “We are no longer using the de-icing company in question.”

The de-icing company, the nationwide outfit Trego/Dugan Aviation, said in a statement:

“Nothing of this sort has happened in the past 50+ years and we have vigorously attacked the underlying circumstances to prevent anything like this in the future.”