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I've heard some conspiracy theorists claim that if you were to bring a soda can or a bad of chips onto an airplane, they would pop?

Is this true? If so, why?

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    Anybody can observe that the food service on aircraft includes soda cans and bags of chips, some of which seem a bit bloated but don't actually "pop". – Greg Hewgill Jul 16 '18 at 02:00
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    Reddit TIFU of the year – Noah Krasser Jul 16 '18 at 06:57
  • By coincidence, this weeks' BBC Click (probably geolocked to the UK) went to Ford's climate testing center - just after the 10 minute mark there's a short clip simulating high altitude, with 3 bags of crisps sat on the car, 2 of which pop. – James Thorpe Jul 16 '18 at 07:34
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    At school we put soda cans into vacuum chambers, nothing happened. Bag of chips at high altitudes puff up extremely but I think that its the extra pressure of grabbing them that makes them pop (had that happen to me once). Soda cans should be stable enough to withstand a lot more abuse, sometimes even if you want you can't make them pop by throwing them at the ground. – PlasmaHH Jul 16 '18 at 08:17
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    Nice question Jack! I think this might be better suited to https://skeptics.stackexchange.com/ though :) – Korthalion Jul 16 '18 at 08:54
  • @Korthalion Not unless a credible source is included in the question. – Mast Jul 16 '18 at 14:22
  • Anedoctally, a bag of chips in the back of my family's car popped on our way up to Mauna Kea observatory in Hawaii. Notably, this is one of the few places where you ascend very quickly (sea level to 14k ft in ~2hrs), so maybe speed plays a role? – mbrig Jul 16 '18 at 14:33
  • @Mast Why would a question need posting on skeptics.se if the OP had a credible source? – Korthalion Jul 16 '18 at 15:25
  • I had a ZipLoc bag with crisps in it open by itself on an aircraft during ascent. It made a mess in my bag. No big deal though. – JohnEye Jul 16 '18 at 15:31
  • @Korthalion The other way around. It could only be posted there if the OP had a credible source. IMO it's just fine here though, but you can take it to meta if you disagree. – Mast Jul 16 '18 at 16:06
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    Conspiracy theorists?... Telling you that soda cans and chip bags should burst?... And, the fact that commercial airline galleys are stocked with cans of soda and bags of chips that don't burst proves... some nefarious plot? – Solomon Slow Jul 16 '18 at 16:56
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    Something not mentioned is things put in the cargo hold. Many people think the cargo hold is unpressurized and that therefore chips or soda in there would be exposed to the low pressures at 35,000 feet. However, the hold is pressurized (though not usually heated), because it's easier to pressurize a cylinder than a "D" shape (the cabin with a flat floor), so anything in the answers should apply to the hold as well. – Skyler Jul 16 '18 at 17:57
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    I think a big clarification needed is are you asking if they will pop, or perhaps could pop. Will they? No, not likely. Could they, sure given the right circumstances. – BruceWayne Jul 16 '18 at 20:39
  • @Mast Doesn't need taking to meta, it's quite a clear cut case. OP has a question about whether an urban myth is true - it's fine on here but would be better on skeptics. – Korthalion Jul 17 '18 at 08:31
  • @Korthalion I think what they meant was a notable source, not necessarily a credible one. Skeptics does requires that claims have a notable source, otherwise the question will be closed. At any rate, the question has been answered here... just not really by the most highly-voted answers, unfortunately. – reirab Jul 17 '18 at 15:28

7 Answers7

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Not likely. Consider how food products normally make it to you.

Any competent US maker of soda or chips will design their product to be shipped

  • on Interstate 70 or 80, via Sherman Summit (8650') or the Eisenhower Tunnel (11,158')
  • or more likely by rail, via again Sherman Summit (8015') or Moffat Tunnel (9239').*
    Aircraft are pressurized to a pressure altitude of 8000' typically, so Sherman Summit (rail).

If a food manufacturer were to botch their packaging, they wouldn't have your problem of a soda can bursting, they'd have an entire container load of sodas or chips burst and ruined for sale. That is simply unacceptable, so manufacturers have a big incentive to get this right.

Other markets will have similar issues - the EU has the Alps, and China and India have the Himalaya. It does not apply to regional sellers in flatland areas, so a regional/indie Florida chipmaker, all bets are off.

It does, however, apply to soda manufacturers, whose cans must endure extreme temperature (e.g. solar loads in a car) also in high places.

* Tennessee Pass (10221') doesn't count, it is weedgrown, rusty and cut in several places, being held for future capacity needs.

Harper - Reinstate Monica
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    Shaking a can of soda doesn't significantly increase its internal pressure, and doesn't make it more likely to burst. A shaken can of soda explosively foams after opening because of the large number of nucleation sites, not increased pressure. – Sneftel Jul 16 '18 at 09:33
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    Sankt Moritz is only at 6000 feet. As for tunnels, the (old) Gotthard tunnel in the Alps is only at 3600 feet, which is pretty typical. In fact, the new batch of Swiss tunnels is even lower, it's been nicknamed Swiss Metro. Furthermore, unlike the Rockies, it's often easier to ship something around the Alps. – MSalters Jul 16 '18 at 10:58
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    @Sneftel: A possible source of the confusion is that shaking a still mostly full screw-lid bottle of soda right after you've resealed the lid will increase its internal pressure markedly -- for the same reason. – hmakholm left over Monica Jul 16 '18 at 12:41
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    This is just wrong. Potato chip manufacturers actualy make different production runs for different destinations. Chips that are specifically destined for in-flight airline use or are intended for shipment over mountain locations (ie: to the US west coast) are filled with slightly less air and, in the latter case, are shipped in special containers with sealed polymer liners inside the cardboard shipping carton to help keep a higher pressure around the bags, if needed. Where possible, high altitude shipment routes are avoided. The unprotected individual bags can certainly pop at altitude. – J... Jul 16 '18 at 13:37
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    @J... That might be worth writing up as an answer if you can track down some sources, given the amount of seemingly guesses in the answers here. – mbrig Jul 16 '18 at 14:35
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    @mbrig No sources other than just knowing - if you want to beg Google for an hour or two you might track down some whitepapers. – J... Jul 16 '18 at 14:39
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    @mbrig Actually, it seems not that hard : My Worst Load Ever: Hauling Oregon Potato Chips to Texas – J... Jul 16 '18 at 14:40
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    From UP - Shipping guidance – J... Jul 16 '18 at 14:52
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    News : Selling the Cape to the world – J... Jul 16 '18 at 15:01
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    @J...: That may be true of shipping - I have no way to know - but what about after it's purchased by the consumer? I might buy a bag of chips at the store (4400 ft) and take it to my friends' place, crossing an 8900 ft pass. Or I might even take a bag hiking around 10-14K ft mountains. – jamesqf Jul 16 '18 at 16:33
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    @jamesqf Then your chip bag will pop. It happens all the time. – J... Jul 16 '18 at 16:52
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    @J...: Granted, I'm not a big consumer of chips, but "all the time" seems to be so infrequently that I've never seen it, or heard of it happening. And I did that drive over the 8900 ft pass myself for several years... It would also appear that a lot of chips &c are packaged at lower elevations than the 4400 ft grocery store, as the bags are usually puffed up, presumably from lower outside pressure. – jamesqf Jul 16 '18 at 21:47
  • That's been my experience too, I often smuggle bags of chips over the continental divide from eastern regional makers. What‘s more, most of those makers will cheerfully mail-order their products. I don't believe they make special production runs solely for their occasional mail orders. – Harper - Reinstate Monica Jul 16 '18 at 23:12
  • @Harper It depends on the manufacturer - larger and smaller shops will have their own strategies depending on the volume they produce and the equipment they have. Larger producers have gone the way of developing new bagging equipment and adhesives to toughen against altitude changes. Some mid-sized producers will pack differently depending on the destination and most will be selective about shipping methods and routes where it matters. – J... Jul 17 '18 at 18:05
  • Australian chip packets and soft-drink cans are sent to the US to travel over mountains? Wow! Just wow! I had no idea that's how food products normally make it to me! – CJ Dennis Jul 18 '18 at 07:17
  • @CJDennis it does not apply to regional sellers in flatland areas – Harper - Reinstate Monica Jul 18 '18 at 14:27
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I can confirm that bagged snacks can pop from the pressure difference. Climbing through 7,000 feet (on our way up to 9,000) in an unpressurized PA32 we heard a quite loud POP. In and out of clouds at the time we were busy in the front seat, didn't observe any flight control or systems issues. Fortunately had a person in the back that looked around there for us. After trying to look outside at airplane surfaces for awhile she turned her attention inside and found a bag of popcorn (the already popped, snack style) had exploded...

Brian Knoblauch
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    This has happened to me as well. it's happened to me climbing at about 12,000 feet, flying GA aircraft at about 10,000 feet and once driving over a mountain pass at about 8,500 feet. – David Schwartz Jul 17 '18 at 18:47
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I brought a bag of chips on a Quantas A380 flight recently and it ruptured during ascent. Sitting very close to the bag, I thought the sound was quite loud. Nobody else noticed it. Results may vary from bag to bag.

Chip bags are pressurised relative to the atmosphere. As the plane climbs, the pressure in the cabin drops, which increases the pressure difference. This pressure difference may exceed the strength of the bag, causing it to break.

Anonymous Physicist
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    purely anecdotal stories can help make a point, but aren't enough. The bag could have ruptured for any number of reasons. – jwenting Jul 16 '18 at 05:32
  • Hi, what was the bag size and manufacturer please? – Cloud Jul 16 '18 at 06:23
  • @jwenting Could you please name for me one reason for bag popping open during take off other than pressure difference? – okolnost Jul 16 '18 at 07:13
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    @okolnost "during takeoff", the plane is pretty close to ground level. If you had said "shortly after takeoff" that might have been convincing. – Martin Bonner supports Monica Jul 16 '18 at 07:48
  • @okolnost you stuffed it in the seatpocket in front of you and bump it with your knee. Heck, I've come home from the supermarket with bags of crisps torn when the grocery bag fell over, crushing the crisps bag under some bottles of soda... – jwenting Jul 16 '18 at 08:40
  • @MartinBonner the internal cabin pressure is set by the crew and quite often it happens during or even before the takeoff. It can be done as soon as the cabin is sealed (hermetised). – Ister Jul 16 '18 at 12:41
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    @Ister Are you saying that there are pumps in the aircraft which can lower cabin pressure below ambient? That seems extraordinary to me. – Martin Bonner supports Monica Jul 16 '18 at 12:44
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    @Ister: Second that comment. You're essentially claiming that airplanes have hardware on board which is totally unnecessary, but does add extra weight AND electric risks? Airplane hulls are designed for overpressure (tensile load), not underpressure (compression load). – MSalters Jul 16 '18 at 13:57
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    @Ister, pilots (or the automatic system) don't set pressure in the cabin, they set the schedule of pressure change. As it happens, after the cabin is sealed, the pressure is typically increased slightly, making it higher than ambient (i.e: 'negative' cabin altiture). – Zeus Jul 16 '18 at 14:13
  • @MartinBonner There's an issue with a low pressure region forming over the outflow valves and it causes a negative pressure bump right after rotation. Modern aircraft are pre-pressurized to prevent this, older designs don't. – user71659 Jul 16 '18 at 23:11
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    @MartinBonner "during takeoff" was an error on my part, the plane was not near the ground, but was below cruise altitude. Sorry I did not note the altitude or the precise type of chips. – Anonymous Physicist Jul 17 '18 at 01:28
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Soda cans are designed to withstand much larger amounts of pressure from the inside. Ever tried to squeeze a soda can that has just been shaken? Taking away outside pressure can only increase the inside pressure by 1atm - and that would mean placing the can in a vacuum. Simply shaking a can will increase the inside pressure much more than that and a can is supposed to survive even more than just shaking. You can make a soda can burst by heating it up, but that'll require quite a bit of heat.

Bags of chips are not designed to withstand large amounts of inside pressure because chips to not generate any pressure like a carbonated liquid does. Depending on the pressure at the time of packaging and the packaging itself, they usually do "inflate" a bit on a flying aircraft and in rare circumstances they may even burst.

[edit]I decided to dig out some numbers, so here we go:

https://hypertextbook.com/facts/2000/SeemaMeraj.shtml

A cooled soda can have an internal pressure as low as 1atm (~100kPa) up to more than 2atm.

At room temperature this goes up to around 4atm.

So taking a can out of the refrigerator and putting it on the table increases the pressure more than placing a (cooled) can inside a vacuum.

As has been pointed out in the comment, shaking may not significantly increase pressure. (I was expecting a more than minor increase because a bottle that has recently been shaken certainly feels "harder", but OTOH you need to be really careful when it comes to "feeling" things like pressure!)

Temperature, however, does increase pressure significantly and I would expect a soda can to be designed to withstand the pressure of a hot summer day in the shade - i.e. 40°C/100°F. (It's not trivial to predict the pressure at that temperature, so I'm not trying.) [/edit]

Thomas
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  • Copying Sneftel's comment on another answer: Shaking a can of soda doesn't significantly increase its internal pressure, and doesn't make it more likely to burst. A shaken can of soda explosively foams after opening because of the large number of nucleation sites, not increased pressure. – hmakholm left over Monica Jul 16 '18 at 12:34
  • I've personally seen a galley get covered in soda when a flight attendant tried to open a can and it ruptured instead. I would call that an "explosion". Not saying a one-off observation suggests that such things have a non-trivial probability of occurring, but they certainly "can". – supercat Jul 16 '18 at 16:09
  • To add to the last paragraph, I've recently been the 'victim' of a can left in a car on a hot day. The can didn't spontaneously explode. However as soon as I pulled the tab slightly, the 'ring pull' area of the can top (which normally would fold inside the can) was blown clean off the can, hitting my hand painfully on the way. It only took a very small break at a weak point for it to fail instantly. – Graham Jul 16 '18 at 22:26
  • Just for what it's worth, a friend of mine use to work at a bottling plant. As I recall, he said 1 liter bottles can pretty routinely hold up to about 100 PSI, and 2 liter bottles around 80 PSI. In both cases, they're pretty much globe shaped (other than the neck/top of the bottle) before they burst. He didn't deal with cans though, so I don't have any solid data on what they'll withstand. – Jerry Coffin Jul 17 '18 at 23:06
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I have never had a bag of chips pop in a commercial flight (although I've had bags that seemed to be right on the verge).

On the other hand, in a single engine non pressurized Beechcraft Bonanza we had a bag of chips explode in the cabin as we were climbing to our cruising altitude. It's been too long for me to remember our altitude, but it can and does happen. Scared the crap out of me as it was near me when it happened and it was quite loud.

Can of soda? Haven't had one explode in the air. I have had cans of soda explode due to heat though in the summer in the trunk of my car, on several occasions. Luckily in my case they were all seltzer water.

xcr
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The only reason it might pop is if the cabin pressure were to suddenly disappear. That's explosive decompression and if it happens you've more serious problems than having some soda or crisps soil your clothes or whatever is in the bag it popped in.

I did once get the advise to open any cans or bottles containing carbonated drinks I was planning to consume during a flight before takeoff, but that was on board an old Soviet era aircraft with a faulty pressure cabin. In such cases the sudden release of pressure can cause the liquid to spill out, similar to shaking a bottle of soda violently before opening the lid would do on the ground (or, as my aunt once did mistakenly, freeze cans of soda so they'd be nice and cold for next day's road trip, then leaving them out in a hot car where they built up so much pressure they ruptured).

jwenting
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    How and why were you flying on anything with a "faulty pressure cabin"? xD – Cloud Jul 16 '18 at 06:25
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    @Cloud Siberia, 1980s, Aeroflot An-24. Was the only available aircraft at the field we'd made an emergency landing on in a Tu-154 the previous day. – jwenting Jul 16 '18 at 06:59
  • well, now you'll have to go to North Korea to fly on a tu154, if yuo have a death wish :) – Cloud Jul 16 '18 at 07:33
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Definitely. I have seen it on older aircraft at medium altitude chips bags can pop easily. Altitude at which no cabin pressure is even required.

user3481141
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