A pilot has told how security on his aircraft was tightened to presidential standards hours after 9/11 as airlines were warned of the possibility of more terrorist attacks.

Nick Eades was due to fly a long-haul British Airways Boeing 747 from Bombay - now Mumbai - to London on the night of the New York atrocity, which claimed 2,996 lives.

The flight had originally been fully booked for around 400 passengers but the pilot recalled how half of those who were due to travel cancelled their tickets amid heightened anxiety over flying.

"One of my main concerns was the welfare of the crew," said Mr Eardley, as the 20th anniversary of the Twin Towers attacks was marked world-wide. "All of them had undoubtedly been affected to some degree.

"Alarmingly all the aircraft involved in the atrocities had suffered a breach of the flight deck.

"The hijackers had managed to enter the flight deck, overpower the flight crew, and fly the aircraft to its target. 

"Our priority, therefore, that night was to ensure that nobody could access the flight deck except the crew."

He said it was fortunate that the flight deck of the 747 is on the upper deck, which is normally restricted to around 30 Club Class passengers and is a popular choice because it resembles a private jet.

"We decided to close this cabin to passengers and station one of the more burly flight attendants at the base of stairs to prevent unauthorised access," said Mr Eades.

"We would then position another crew member at the top of the stairs to act as a second deterrent and alert the flight crew should an attack occur. 

"Finally, our flight engineer, a gentleman you would not like to come across in a dark alley, would guard the flight deck door with the aircraft's crash axe.

"This hopefully would give us a very secure way of protecting the plane. All present agreed to operate home on this basis," said the Sussex-based pilot, whose grandfather worked on the Glasgow shipyards.

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He said he found out many later that the captain of Air Force One, carrying President Bush and another Boeing 747, had implemented the same precautions in the aftermath of the attacks. 

"Apparently, even the president of the United States could not access the upper deck on his aircraft," said the pilot.

He recalls being surprised after a manager rejected his plan to close this portion of the plane fearing it would upset passengers.

"Passengers have always tried to book the upper deck on a 747 as it resembles a private jet rather than an airliner. 

"I was taken aback by this attitude, especially at such heightened risk. 

"Containing my anger as best I could, I asked the agent to please call the local area manager, the most senior manager in Bombay. After a quick discussion, I handed the phone to the squirming duty manager. The upper deck was now closed."

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He said crew members guarded the stairs "at all times" during the return flight, which passed without any issues until a last-minute security scare.

"After all our passengers had disembarked, I stood up and was about to go downstairs to thank the crew when a passenger came up the stairs.

"This was against everything we had previously agreed on, and I tensed myself for what was to come. 

"The look on my face must have alerted the passenger. He very quickly produced his identity card and it was the Heathrow airport duty manager," said the pilot, who is married with two grown-up sons.

The crew were told that classic 747's were to be immediately grounded before being disposed of as they were deemed less efficient than the newer 747-400. 

Mr Eades is preparing to retire as a BA pilot after more than 40 years flying and hold the record for being the world's most experienced 747 pilot.

Still Improving by Nick Eades will be available in book stores and online outlets in November.