An Air India flight to Frankfurt was forced to return to the Delhi airport on Wednesday after it suffered mid-air decompression. “Air India flight AI121 operating from Delhi to Frankfurt today faced an issue of decompression and returned to Delhi,” the airline said in a statement. “No passenger suffered any injury.”

The air is extremely thin at higher altitudes due to low atmospheric pressure and oxygen. In order to avoid injuries and ill-effects on flyers’ health, aircraft maintain a specific internal cabin pressure.

According to unidentified airline officials, the decompression in the Boeing 787 Dreamliner occurred 15 minutes after take-off at a height of around 20,000 feet, PTI reported.

“The pilot decided to return as the oxygen masks dropped and the plane landed safely at Delhi airport,” a senior Air India official told the Hindustan Times. “The passengers were asked to deboard and were taken to the terminal.”

The pilot turned back from Rajasthan air space and landed safely in Delhi at around 4 pm, according to ANI.

“The flight will now operate with a change of aircraft at 0600hrs [6 am] on 7th March from Delhi,” added the statement. “All passengers are safe and are being extended all assistance at Delhi.” The standard departure time of the flight is 1.35 pm.