NEW DELHI: In possibly the first delay of its kind, an Air India captain on Wednesday morning refused to operate an aircraft as one of the emergency oxygen masks in the cockpit was ‘dirty’. AI operations team tried to reason with the pilot that he should not delay the flight for this reason and get the mask cleaned with cologne like cabin crew disinfects masks for making announcements. But the pilot stuck to his ground, insisting that the mask be cleaned and sealed. As a result, the Delhi-Kochi flight , AI 467, with a scheduled departure time of 5.35 am was delayed by almost three hours.AI chairman Rohit Nandan has taken a very serious view of this delay and ordered a thorough probe into the antecedents of the commander to check if he has been delaying flights on ‘specious’ grounds in the past too. “We are trying our best to improve our on time performance and silly excuses like these cannot be tolerated to delay a flight for so long. This was the first fight the aircraft was to operate on Wednesday. A delay in Delhi meant all the other flights it was to operate were consequentially delayed by about three hours,” said a senior AI official.The ‘dirty’ mask in question belonged to the portable oxygen cylinder that is kept in the cockpit. This is to be used by pilots if they have to leave the cockpit in an emergency situation like fire, smoke or de-pressurization in the cabin. Smoke from oven is a common occurrence in aircraft and even for checking them, pilots are supposed to use this portable cylinder.The portable oxygen bottle is in addition to the quick donning pneumatic mask that is in the cockpit for both the pilots. Putting on these masks is the first thing pilots have to do in the event of any emergency so that they remain conscious and are able to land the plane safely.Cockpits do not have overhead oxygen masks that passenger cabins have. The overhead masks can supply oxygen for 15 minutes — enough time for an aircraft to descend to 10,000 feet or normal atmospheric pressure — in the event of de-pressurization. Cockpit masks have oxygen supply for longer periods.“The operations team reasoned with the pilot to use cologne to clean the mask and operate the flight. But he did not do that. As a result, the flight got delayed by several hours,” said a source.However, some pilots questioned why it took AI so long to clean the mask. Very often pilots point out that the cockpit is dirty and then the maintenance staff cleans it in minutes.