When you drink wine is takes between 30 to 60 minutes for its maximum effect on the body. So if you consume several wines in a short period of time - you can expect your body to start to find it difficult to cope, as you drink more alcohol than your liver can process. In such a case the excess alcohol will travel through your bloodstream un-metabolised and un-processed. So the concentration of alcohol in the blood stream will increase.
As it travels through your bloodstream, the alcohol eventually reaches your brain, where it acts as a sedative and slows down the transmission between the nerve cells that control your ability to think and move. So when you are travelling on a plane, the atmospheric pressure in the cabin of a plane is lower than it is on the ground near sea-level.
This environment with its decreased air pressure can diminish the body’s ability to absorb oxygen - and it can for some people produce light-headedness, called hypoxia.
So if you drink wine (or any alcohol) during a flight you may notice this effect sooner. This is because of the lower level of oxygen in your blood, you may seem more intoxicated on a plane in the air than you would on the ground after consuming the same amount of wine. But your blood alcohol level will actually show the same percentage as if you drank the same amount of alcohol on the ground at the same speed of consumption.
Another complicating factor is that the air in the plane is very dry, and combined with the diuretic effect of drinking alcohol (makes you want to go to the toilet); you can become dehydrated much faster than you would on the ground.
So to combat dehydration at any time (especially on a plane) make sure you drink water with every wine. And minimise your consumption of salty foods before and during the flight, as this can have an adverse effect by making you even more thirsty and encouraging you to drink alcohol faster.
One glass of wine in the air on a plane is approximately equal to two-three glasses on the ground. This is due to low air pressure effectively thinning the blood. Which means the effects of alcohol can be stronger and faster. But this effect is not solely produced by the consumption of wine - as you may feel more intoxicated because flying at altitude mean less oxygen is getting to your brain, making you also feel light-headed.
The air at 36,000 feet (the height at which most planes fly) is not breathable - this is why airplanes are pressurized. But the air in a planes cabin has far less oxygen than you would breathe if you were on the ground.
If you have ever had a glass of wine while flying on a plane at 36,000 feet, you have possibly noticed that the wine (which you might have had before) often tastes different, even faulty, compared to how it tastes on the ground. This is because altitude and cabin air pressure impact the wine in ways which science has been researching for several years and are still to fully explain. But what is known - not all wine consumed on an airplane tastes as it should.
Which is why you often don’t see people consuming delicate wines in the sky, even if they are flying first class! That being said, there are some wines which drink well when poured on a plane - though these are typically wines with expressive fruit and winemaking characters.
Expressive wines with bold expression of natural ripe, generous fruit flavours and good well balanced use of oak and red wines with well integrated tannins. So at altitude the characters are not so muted. It is true that passengers who fly in First or Business sections can have a larger selection of wine to choose from, but even in Economy the wines you drink should be pleasurable, and hold up to the effects of altitude.
Your senses are dulled at altitude on a plane, making it difficult to appreciate the aromas and flavours which wine has to express. The lower atmospheric pressure, also means that the flavour molecules in the wines aroma are jetting past your sensory receptors so fast, you don’t always catch them all. It is like having a head cold, the pressurised cabin and its dry air dulls your senses and taste buds, and affects your sense of smell by drying out your nasal passage. Since flavour is a combination of all your senses (with 70% of taste based on smell) things taste differently.
The human body needs around 8 glasses of water a day to stay healthy and function at its best. So when flying at altitude, you need to keep your body as healthy as possible to fight dehydration and light-headedness. Dehydration can cause you to lose up to 30% of your sense of smell, which is most of what you experience in a wine. This can make even the best wines taste less expressive and even seem faulty. So keep yourself hydrated, to appreciate the wine you choose on a plane at its best.
For some the stress of flying on a plane has an effect on your senses ability to appreciate wine aromas and flavours. Also the constant noise on an aeroplane (engines, passengers etc..), can affect taste as well, making some flavours more intense, and others muted.
Wines have a tendency to taste more acidic and more tannic at altitude. A wine with strong, aggressive tannins on the ground don’t typically show well at altitude. Whites wines which have an astringent, sharp acidity profile also are not as enjoyable at altitude as more opulent, fruit driven styles. This means that the airline must select fruit expressive wines that are low on both acidity and harsh tannins.
Those little plastic cups you get to sip your wine out of don't help much, either. They do little to help you enjoy the natural bouquet of the wine you have chosen.
Red wines which show more generous fruit, aromas and a balance of oak and tannins and a little age show well at altitude compared to young, segmented wines. But the skill for an airline wine buyer is finding the right combinations.
However, once a wine has been identified that works well at altitude, for the airline comes another issue - trying to ensure the wines supply across their planes. Trying to purchase enough bottles, which is no easy feat considering several airlines serve over 2 million bottles of wine on board each year.
So wherever you travel by plane, don’t expect your choice of wine to change your life, but hopefully the airline (which many do today) have selected wines which don’t lose too much character and are balanced at 36,000 feet - so hopefully which ever sparkling, white or red wine you do choose - you will enjoy the wine with your meal.