By Will Roberts
A mystery smell made a co-pilot feel dizzy and forced a plane carrying 139 passengers into an emergency landing, it has been revealed.
An accident report into the Lufthansa Airbus A321 flight from Frankfurt to London Heathrow describes how the plane's captain had to wear an oxygen mask after a strong smell was reported in the cockpit and the co-pilot began to feel dizzy and nauseous.
In the cabin passengers reported light throat irritation, according to the Air Accidents Investigation Branch (AAIB) report into the incident on October 21 last year.
The plane landed safely at Heathrow airport and nobody on board the flight was injured or suffered any lasting effects of the incident.
However subsequent investigations into the incident have proven inconclusive in terms of identifying what the mystery smell was.
When the crew returned to Frankfurt they were tested but results showed nothing abnormal, while checks on the aircraft itself revealed nothing out of the ordinary.
The report reveals that the co-pilot said he was feeling dizzy and was suffering from eye and throat irritation, while both he and the captain could smell a strong odour. The captain then called a member of the cabin crew, who also confirmed she was suffering from the same symptoms and that passengers had complained about the smell too.
Taking emergency measures, both the captain and the co-pilot put on oxygen masks and requested priority landing clearance. Once on the ground, with the engines switched off, the situation improved, according to the report.
A few passengers reported "light throat irritation" but nobody was seriously suffering.
Hospital blood tests carried out on six members of crew revealed nothing, shrouding the event in mystery.
The AAIB said "This event thus joins a growing number of cases in which there has been a similar lack of conclusive evidence as to the cause(s) of aircraft cabin air quality issues.
"Over the years there have been numerous reviews, studies and research projects on air quality events, conducted in a number of countries."
According to UK Civil Aviation Authority figures, so-called "fume events" occur on approximately 0.05 per cent of all commercial passenger and cargo flights.
The report went on: "In most cases the effects on air crew take the form of 'acute' symptoms such as eye and throat irritation as experienced by the crew of D-AIRX (the Lufthansa plane) although long-term health issues have been recorded.
"However, inconsistent reporting is thought to have affected the quality of the evidence."