It seems that quite a few people are un-nerved by all the odd sounds and weird feelings that you experience on a flight. So I thought it maybe useful and interesting if we put together a list of them all, and their proper explanation. That way, when people hear 3 bings, they will know it is not the Captain telling the crew the plane is about to crash!
The Push Back
- When you get onto the plane it maybe plugged into the airport's power supply. However it may also be using its own generator (Auxiliary Power Unit, APU) in the tail. This will be that high-pitched scream you hear.
- When you sit down, you may notice smoke coming from the air conditioning vents above the windows. The plane is not on fire! It is simply the cold air condensing water out of the warmer moist air that is already in the plane. You will also hear a load of clunks and bangs. This will be the crew wheeling and stowing the food, and more importantly the duty free. It will also be the ground crew throwing your luggage into the hold (as hard as they can!). You may also hear them closing the cargo doors, making a whir and a thump.
- The crew will then close and arm the doors. Arming involves turning on the shoots that will go off automatically should the doors subsequently be opened. They then double check this, and ensure that the safety pins (usually with a big red ribbon attached to them) are inserted into the arming mechanism. "Cross check complete" is then reported to the flight deck.
- As the engines start the aircon will stop and the lights dim. This is not an electrical fault, but just the result of the power being switched from the APU (mentioned earlier) to the main engine generators.
Taxi
- As you taxi to the runway you may smell and acrid burning odour. This would be the exhaust from the plane in front of you - not nice, but nothing to worry about.
- The bump, bump you hear is the wheels going over the expansion joints in the concrete taxiway.
- The brakes may squeal as you slow. Again this is just dust and debris on the friction surface of the brakes and nothing to be concerned about. On an Airbus you may also hear someone having a go at the plane with a large electric drill. In fact this is the Power Transfer Unit, which takes power from one engine to another - an Airbus feature.
- While on the ride to the runway the flaps and slats (the bits that move at the back and fronts of the wings) to test them. They will then extend them into the position they should be for take off, with a whirring of gears and wheels.
- There will be a few bongs on the intercom system just before take off. This tells the crew to sit down, and may be accompanied by an announcement like "cabin crew be seated for take off".
- Everything in the galleys should be properly secured. However you may hear a few things falling over as the plane starts its acceleration down the runway. You may also see the lockers above your head shaking and wobbling around - they are designed to do this.
-
The first moments of flight
- Many airports require a turn pretty quickly after take off. This can be for air traffic control reasons, or to avoid flying noisily over too many houses. It can be disconcerting to see the sky out of one window and the ground out the other. While the turn is perfectly normal (and it is unlikely the plane is banking more than 20 to 25 degrees), if this worries you don't look!
- You will then hear the clunks and bangs of the wheels being retracted - this is done by one of the crew who stays in the hold during take off with a big spanner to wind them up
. The wheels may have been spinning at 100mph or more at take off, so you might feel some vibration as the brakes stop them spinning.
- I think the worst feeling is the swooping, plunging feeling you get about a minute after takeoff. In fact you are just slowing down a little and the upward pitch of the plane reduces slightly - the plane is still accelerating and climbing. But it feels for all the world like you have suddenly gone into a dive - our bodies are remarkably sensitive to changes in acceleration and pitch when deprived of visual reference points. This again is a noise abatement measure, and is very popular with the folks down below in their sitting rooms.
- You may also feel a little turbulence which is caused by thermal effects on the air above the hot city/hills/desert you are flying over, the clouds you are passing through, or the change in temperature as you move from over land to over sea.
- at 10,000 feet the pilots will use the intercom to bong again - 10,000 feet is a key point in the rules relating to air-travel.
- Finally you hear the flaps and slats adjusting to their in-flight positions. And it's time for a drink [y]
The approach
- The crew will throttle back the engines to start the aircraft descending. As the aircraft slows they will start to extend those flaps and slats again. Passing 10,000 feet there will be the bong again.
- At some point large flaps on top of the wing called spoilers will be extended. These slow the plane still further, but they also cause a very choppy flight for a while.
- As you actually come into land one of three things will happen. The engines will probably rise a bit in pitch, and the plane may wobble around a bit. This is the pilot making last minute fine adjustment to the rate of decent. This will make the landing smoother - what a considerate fellow! Alternatively there maybe no change, which means the pilot is so good that she got it all bang on from the start (or she is a little less considerate). Very, very occasionally the engines will go to high power and you climb off again. This is a normal manoeuvre and can be for many reasons - an unexpected gust of wind, a deer on the runway, even "something doesn’t quite feel right". Usually it’s the plane just before you not exiting off the runway quite quickly enough. Very rarely you may briefly touch down before rising again for the "go-around". Either way, this is not a last-ditch manoeuvre, and is well planned for by the crew and air traffic control.
- The wheels will touch the ground - back ones fist then the front ones - and the engines will fire up in reverse thrust to slow the plane. The spoilers will also shoot up (and sometimes other bits on the engines, which is to do with the reverse thrust) and the brakes will squeal.
- If the pilot lands right in the middle of the runway you will hear the wheels bumping as they roll over the centreline lights, a bit like cats eyes on the road. As the plane taxis you will hear the flaps and slats retracting again, and the Power Transfer if you are on an airbus.
- The seat belt sign will finally go off, with another bong of course, and the power may be switched to the APU with another flashing of lights. Welcome to London Heathrow, it's time to complain about your lost luggage!
There is one noise I have never worked out. If is during climb, but only sometimes, and sounds like ball bearings rolling down inside the roof above your head - any ideas anyone?
The Push Back
- When you get onto the plane it maybe plugged into the airport's power supply. However it may also be using its own generator (Auxiliary Power Unit, APU) in the tail. This will be that high-pitched scream you hear.
- When you sit down, you may notice smoke coming from the air conditioning vents above the windows. The plane is not on fire! It is simply the cold air condensing water out of the warmer moist air that is already in the plane. You will also hear a load of clunks and bangs. This will be the crew wheeling and stowing the food, and more importantly the duty free. It will also be the ground crew throwing your luggage into the hold (as hard as they can!). You may also hear them closing the cargo doors, making a whir and a thump.
- The crew will then close and arm the doors. Arming involves turning on the shoots that will go off automatically should the doors subsequently be opened. They then double check this, and ensure that the safety pins (usually with a big red ribbon attached to them) are inserted into the arming mechanism. "Cross check complete" is then reported to the flight deck.
- As the engines start the aircon will stop and the lights dim. This is not an electrical fault, but just the result of the power being switched from the APU (mentioned earlier) to the main engine generators.
Taxi
- As you taxi to the runway you may smell and acrid burning odour. This would be the exhaust from the plane in front of you - not nice, but nothing to worry about.
- The bump, bump you hear is the wheels going over the expansion joints in the concrete taxiway.
- The brakes may squeal as you slow. Again this is just dust and debris on the friction surface of the brakes and nothing to be concerned about. On an Airbus you may also hear someone having a go at the plane with a large electric drill. In fact this is the Power Transfer Unit, which takes power from one engine to another - an Airbus feature.
- While on the ride to the runway the flaps and slats (the bits that move at the back and fronts of the wings) to test them. They will then extend them into the position they should be for take off, with a whirring of gears and wheels.
- There will be a few bongs on the intercom system just before take off. This tells the crew to sit down, and may be accompanied by an announcement like "cabin crew be seated for take off".
- Everything in the galleys should be properly secured. However you may hear a few things falling over as the plane starts its acceleration down the runway. You may also see the lockers above your head shaking and wobbling around - they are designed to do this.
-
The first moments of flight
- Many airports require a turn pretty quickly after take off. This can be for air traffic control reasons, or to avoid flying noisily over too many houses. It can be disconcerting to see the sky out of one window and the ground out the other. While the turn is perfectly normal (and it is unlikely the plane is banking more than 20 to 25 degrees), if this worries you don't look!
- You will then hear the clunks and bangs of the wheels being retracted - this is done by one of the crew who stays in the hold during take off with a big spanner to wind them up
. The wheels may have been spinning at 100mph or more at take off, so you might feel some vibration as the brakes stop them spinning.- I think the worst feeling is the swooping, plunging feeling you get about a minute after takeoff. In fact you are just slowing down a little and the upward pitch of the plane reduces slightly - the plane is still accelerating and climbing. But it feels for all the world like you have suddenly gone into a dive - our bodies are remarkably sensitive to changes in acceleration and pitch when deprived of visual reference points. This again is a noise abatement measure, and is very popular with the folks down below in their sitting rooms.
- You may also feel a little turbulence which is caused by thermal effects on the air above the hot city/hills/desert you are flying over, the clouds you are passing through, or the change in temperature as you move from over land to over sea.
- at 10,000 feet the pilots will use the intercom to bong again - 10,000 feet is a key point in the rules relating to air-travel.
- Finally you hear the flaps and slats adjusting to their in-flight positions. And it's time for a drink [y]
The approach
- The crew will throttle back the engines to start the aircraft descending. As the aircraft slows they will start to extend those flaps and slats again. Passing 10,000 feet there will be the bong again.
- At some point large flaps on top of the wing called spoilers will be extended. These slow the plane still further, but they also cause a very choppy flight for a while.
- As you actually come into land one of three things will happen. The engines will probably rise a bit in pitch, and the plane may wobble around a bit. This is the pilot making last minute fine adjustment to the rate of decent. This will make the landing smoother - what a considerate fellow! Alternatively there maybe no change, which means the pilot is so good that she got it all bang on from the start (or she is a little less considerate). Very, very occasionally the engines will go to high power and you climb off again. This is a normal manoeuvre and can be for many reasons - an unexpected gust of wind, a deer on the runway, even "something doesn’t quite feel right". Usually it’s the plane just before you not exiting off the runway quite quickly enough. Very rarely you may briefly touch down before rising again for the "go-around". Either way, this is not a last-ditch manoeuvre, and is well planned for by the crew and air traffic control.
- The wheels will touch the ground - back ones fist then the front ones - and the engines will fire up in reverse thrust to slow the plane. The spoilers will also shoot up (and sometimes other bits on the engines, which is to do with the reverse thrust) and the brakes will squeal.
- If the pilot lands right in the middle of the runway you will hear the wheels bumping as they roll over the centreline lights, a bit like cats eyes on the road. As the plane taxis you will hear the flaps and slats retracting again, and the Power Transfer if you are on an airbus.
- The seat belt sign will finally go off, with another bong of course, and the power may be switched to the APU with another flashing of lights. Welcome to London Heathrow, it's time to complain about your lost luggage!
There is one noise I have never worked out. If is during climb, but only sometimes, and sounds like ball bearings rolling down inside the roof above your head - any ideas anyone?
