Ryanair flight made Mayday call over ‘cheesy smell’

A Ryanair pilot radioed a Mayday call to Stansted Airport after noticing a "cheesy smell" in the plane's cockpit, according to an incident report.

Flight crew on the September 2014 Ryanair charter from Almeria to London had to don oxygen masks after the plane’s commander said he felt unwell due to a strong smell.

The plane was met by fire and rescue services upon its arrival at the airport.

A recently released report by Ireland's Air Accident Investigation Unit (AAIU) reveals a series of complaints made about the same Boeing 737 aircraft over an 18-day period in September 2014.

Various flight crews reported “obnoxious” smells on the plane and a fine mist, which in one incident caused pilots to become disoriented.

In a log book entry on September 3rd, 2014, flight crew working on the aircraft noted a “strong smell of engine oil”, causing it to be withdrawn for maintenance.

Almost a week later on September 9th, crew members again complained about an “obnoxious” smell and the presence of a “very fine mist” on the flight deck.

There were further reports of unpleasant smells the following day, before numerous cabin crews noticed a “strong, heavy, cheesy smell” on September 12th, which caused headaches, a “layer on tongues” and disorientation.

The aircraft was withdrawn from service for more repairs, before flying again on September 16th.

There were further complaints of bad smells up until its fifth and final flight of the day on September 18th, when the pilot made the call to Stansted Airport.

Throat irritation

Writing in a log book, the 26-year-old pilot said he suffered irritation to the back of his throat, allegedly caused by “chemical-type fumes”.

The fumes were noticed in the cabin when the flight began its descent in to Stansted, prompting the Mayday notice.

The commander deployed oxygen masks for himself and the first officer during the descent, but declined to alert the flight’s 174 passengers to the situation so as to avoid causing alarm.

The plane subsequently made a normal landing, with no need for assistance.

The headaches and throat irritation experienced by the pilot lasted for two weeks following the incident. He only returned to work the following month.

The first officer reported no adverse effects.

Inspectors for the AAIU did not manage to come to a definitive conclusion as to the cause of the “serious” incident on September 18th.

However, they deduced that an internal oil leak in the plane’s auxiliary power unit probably led to contamination of the air conditioning system, even after the unit was replaced on September 10th.

Both of the plane’s engines had to be replaced between September 1st and 18th, and the auxiliary power unit was replaced twice over the same period.

The aircraft resumed service on September 25th, 2014, after which there were no further complaints about fumes or odours.

The events prompted Ryanair to introduce a new checklist system for troubleshooting the reporting of smells or fumes, the report found.