Flight attendant reveals why you should never order a Diet Coke on planes

By ESTHER MARSHALL

Published: 12:48 BST, 5 May 2025 | Updated: 12:48 BST, 5 May 2025

From demanding an upgrade to refusing to obey the seatbelt sign, there are lots of ways that passengers can make a flight a nightmare for the cabin crew. 

And there’s even an innocent drinks order that could ruin your flight attendant’s day. 

According to one flight attendant, Diet Coke and Coke Zero orders can present a challenge for the crew. 

Taking to Reddit, the flight attendant who said they worked for a domestic airline in the USA, offered to answer passengers’ questions. 

One passenger ‘violet_mango_green’ asked: ‘Is it true flight attendants hate requests for Diet Coke more than sodas with sugar in them?’ 

The cabin crew member replied: ‘I don’t know the science behind it but Diet Coke and Coke Zero are just way more fizzy to pour than other drinks and take forever to fizz down when pouring!

‘I usually just give the passenger the whole can if they ask because I could have served three more passengers by [the] time the cup is full.’ 

And, according to McGill University, the reason why Diet Coke fizzes more is because it has a higher viscosity level. 

According to one flight attendant, Diet Coke and Coke Zero orders can present a challenge for the crew

Original Coke may be easier for flight attendants to pour on a plane

This means that its fizzing potential is ‘slightly diminished’  but when ‘bubbles do form’ they tend to ‘be more stable’ and last longer. 

The fizzier bubbles explain why a Diet Coke or Coke Zero is generally a bit more difficult for flight attendants to pour than a sugary drink. 

Meanwhile, another flight attendant recently took to TikTok to warn passengers to avoid drinking the coffee on a plane. 

The flight attendant claimed that crew are required to empty used coffee pots into the plane’s toilet. 

He explained: ‘When you take a coffee pot and dump it in the toilet, in order to not make a huge mess everywhere you kind of have to get a little close to the toilet.’ 

And an etiquette expert has revealed exactly when it’s acceptable to take your shoes off on a plane.  

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Flight attendant reveals why you should never order a Diet Coke on planes

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