We all know it's statistically less fatal to fly than to drive a car.

We also know you're more like to get hit by lightning than be involved in a plane crash.

But despite this, we still freak out when a bump happens mid-flight, or if an unexpected sound emanates from below the fuselage. Visions of spiralling towards the earth fill our minds almost uncontrollably.

Luckily, one pilot from Monarch airlines has soothed passengers' fears by explaining what all the creaks, groans, and bumps mean when you're on a plane.

Roar of the rear engine

Passengers boarding at the rear of a plane will often hear the roar of an engine, despite the plane remaining very much on the tarmac.

This is the sound of the Auxiliary Power Unit (APU) - which at this point in your journey is being used to generate the air conditioning in the cabin.

Most airports that we visit – Spanish ones in particular – insist that we connect to their ground air conditioning units, a local noise abatement restriction. Whilst quiet for the airport they are not very effective in the cabin, where the temperature can rise uncomfortably at times.

It's when the temperature gets too high in the cabin that they switch on the APU, which turns on one of the air conditioning units under the plane. These units themselves can also make a lot of noise, like a banshee or a muffled roar.

Rumblings below your seat

No this isn't gremlins. For passenger planes which still carry baggage below, rumblings in what seem to be innards of the plane are actually just bags being locked into place by the handlers.

The high pitched whine that comes before take off is the sound of the baggage and cargo doors being closed using a hydraulic pump under the wing.

Dog barking

Don't worry, your pooch's medication hasn't worn off. According to Monarch, if you're on an Airbus the sound of the plane's three hydraulics systems being started sounds like dog yapping.

The aircraft's three hydraulic systems are now all up and running, and the power transfer unit (PTU) integrates them. This results in a series of yelping sounds, usually three, coming from under the aircraft floor, as the three systems take their normal load


During taxiing, airflow sound will reconfigure due to pressurisation. You might hear something though as the wheels run over centrelights on the runway.

There will be the occasional ‘thump-thump-thump’ as the nose wheel runs over the runway centreline lights; we try to avoid this, but it is not always possible.

All the toilets in the world flushing

On some aircraft, the sound of the landing gear being raised up during take off, is akin to something rather odd.

This has been unkindly described as 'sounding like all the toilets in the world being flushed at once, but on the A320/321 (and the Boeing 737) it’s a much simpler affair.

Noises will remain constant once a plan is cruising. As you prepare to land, the bangs and whoops will return.

More rumbling

Air Traffic Control will also require specific speeds and rates of descent on the way down, so in addition to changes in engine power we may need to use speed brakes on the wing. These can produce a rumble, and a slight buffeting, particularly in the rear of the aircraft.

This is apparently becoming more common, as the skies get busier.

Moreover, aircraft are expected to avoid flying level for noise reasons, meaning that regular declines in altitude are more frequent and therefore the speed breaks are applied more frequently.

Creaking and rattling

As you go to land, the engines will be turned down, meaning that you can suddenly hear all the noises they were previously obscuring.

If there is turbulence you will hear the cabin fittings creaking and rattling, and you may see the overhead bins moving slightly. This is normal, and designed to happen!


As you land and halt on the stand, the pilot will set the parking break, producing a final audible clunk.


That's not the aircraft. That's the sound of people clapping for landing safely. It's the little things.

The guide in full is available on Monarch's website.

HT The Mirror

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