The first officer heard the strange noise and immediately turned towards the pilot-in-command.
He wasn’t surprised to see the captain looking forward seemingly unaware of the loud surge of air. Over the first few days, the FO noticed the captain was a little hard of hearing. Earlier, in the hotel van, the skipper did not realize a flight attendant was telling him a story until she politely tapped him on the shoulder. Sad, because in those days, the captain could not have been more than fifty nine years old.
“Did you hear that?” the FO asked loud enough to avoid having to repeat himself.
His response indirectly answered the question.
“It sounded like a loud surge of air… maybe from the air conditioning ducts?”
“I didn’t hear anything,” the captain mumbled as he continued rolling towards the departure runway.
Just then, the chimes and dings of flight attendants calling each other was faintly heard behind the flight deck door. The FO realized the cabin crew heard the noise and were discussing it over the intercom. He surmised it would only be a matter of seconds before they called up to the flight deck.
The obnoxious tone unique to the Airbus blared through the speakers informing the pilots that the lead flight attendant was calling.
“I bet they heard it too,” the FO said to the captain. FAs will only interrupt a sterile cockpit if they have safety concerns.
“Then, you answer it.”
In addition to partially deaf, he was a little grumpy.
The second-in-command answered the call from the back.
“Uh, we just heard a strange noise back here. It sounded like a gust of wind going through the airplane.” The lead flight attendant described the noise almost exactly the way the first officer heard it.
“Did you feel any air moving? Or, just the noise?” asked the FO.
“Just the noise.”
“OK, we’re going to troubleshoot a little bit and get back to you.”
It was an unusually quiet day at the large, international airport. By the time the first officer hung up the phone, they were next for takeoff. The captain was itching to go, but his hands were tied after his four crew members all reported hearing the same odd and concerning noise.
He begrudgingly agreed to troubleshoot.
There were no other aircraft behind their jet.
After setting the parking brake, the captain ran up the engines and called the maintenance department for guidance. There wasn’t a “Strange Rush of Air Noise” checklist in any of the manuals.
All the engines and systems looked completely normal.
Maintenance suggested that the APU probably released one last surge of air when it completed its shut down cycle. (The APU runs for a bit after selecting the switch to OFF.) It was a logical explanation and the crew was confident there was nothing wrong with their aircraft. The flight attendants also agreed that continuing was the only justifiable option.
Moments later, the right seat pilot slowly advanced the thrust levers to the takeoff position.
All indications were normal as the Airbus accelerated down the runway.
Climbing out of the busy airspace towards the flight levels, the aircraft pressurized on schedule.
Once at cruise, all possible malfunctions related to a rush of air had been ruled out.
There was nothing wrong with the jet.
A few hours later, the aircraft touched down uneventfully at their layover destination.
After a brief taxi, they arrived at the gate. The parking checklist was completed as the jet-bridge approached the forward cabin door.
Both pilots were gathering their belongings when they heard a loud knock on the flight deck door.
Any knock soon after parking would be unusual. No one really bothers the pilots until they are ready to exit the cockpit. The knock’s urgency suggested that someone really needed to speak with the two guys up front.
The captain opened the door to find a wide eyed, somewhat excited ramp worker on the other side.
“Do you know you have a blown tire?” he asked.
The two pilots went down to the ramp to inspect the mains. They found one of the four tires completely deflated with a large hole in it. Other than the hole, it was completely intact. It hadn’t shredded or sustained any other noticeable damage. It just hung there while the other main held up that side of the aircraft.
“I guess that explains what we heard before takeoff,” the first officer said nonchalantly as he stared down at the wheel assembly.
After a brief debate, the captain conceded it would have been too great of a coincidence to hear an unusual loud rush of air and arrive at the destination with an unrelated blown tire.
The airline had not purchased the option of displaying tire pressures in the flight deck.
The tires all looked good on the pre-flight walk-around.
There were no aircraft behind them during their taxi. Perhaps another pilot would have seen the flat tire?
When the tire blew, the rush of air must have hit the strut. As the air quickly ejected from the tire, the air frame probably become a conductor for the noise. As unbelievable as it seemed, almost the entire crew inside the aircraft heard a noise that emanated below the wing outside the plane.
After writing up the tire in the maintenance logbook, they walked out, boarded a van and headed for the layover hotel.
Along the way, they debriefed.
It bothered both of them tremendously that they had no way of knowing the tire had gone flat. The first officer noted that only having three mains on the concrete during takeoff and landing did not alter the handling characteristics. The captain also had not noticed anything abnormal during the taxi-in.
They both acknowledged the potential safety hazards if the tire had shredded and were thankful it stayed intact. Each wondered about any unknown performance penalties. Like so many things in aviation and life in general, they needed to learn from the experience, shrug it off and move forward.
The captain has long since retired.
You can bet the first officer will speak up the next time he hears that noise.
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