A cardiac arrest is when the heart suddenly stops pumping blood effectively due to a malfunction in the heart’s electrical rhythm. This can occur in someone who’s had a heart attack or due to other underlying heart conditions. If the heart isn’t restarted into a normal rhythm within minutes, the person will not survive. While CPR (cardiopulmonary resuscitation) can keep blood circulating, the only effective way to restore a normal heart rhythm is by using a defibrillator to deliver an electric shock. That’s why having defibrillators (AEDs) on planes is so important; in the rare event a passenger suffers a cardiac arrest mid-flight, an AED can provide a potentially life-saving shock even before an emergency landing is possible. In short, aircraft carry defibrillators because they dramatically improve the chances of survival from sudden cardiac arrest in the air.

You might wonder if the act of flying or being at high altitude makes a cardiac arrest more likely. The reassuring answer is no, there’s no clear evidence that air passengers are more likely to suffer a sudden cardiac arrest just because they are on a plane. In-flight medical emergencies are extremely rare. Factors like sitting still for long periods, mild dehydration, or lower cabin oxygen levels can contribute to other issues (for example, blood clots or feeling faint), but sudden cardiac arrest can happen anywhere and isn’t proven to be more common on aircraft. The key difference is that if a serious medical event does happen in the air, you can’t get to a hospital quickly, which is exactly why having an AED on board is so valuable.

In the UK and Europe, there is currently no law that requires all aircraft to carry defibrillators. Airlines are obliged to carry basic first aid kits and train their staff in first aid, but carrying an AED is not a legal requirement. Despite this, many UK and European airlines have chosen to include AEDs voluntarily as part of their onboard medical kit (as shown by our list above). By contrast, in some countries, there are mandates: in the United States, since 2004, the Federal Aviation Administration requires all commercial passenger flights (with at least one flight attendant) to be equipped with an AED and to have crew trained in its use. This means all major U.S. carriers (and many other international airlines, by company policy) do carry defibrillators on planes as standard.
So, if you’re asking “do airplanes have defibrillators by law?”, the answer depends on the region. In the US, yes, by law; in the UK and most other places, no legal mandate, but most airlines carry them anyway out of safety considerations.

Thankfully, medical emergencies during flights are quite uncommon. There is no mandatory global reporting system for in-flight incidents, so exact numbers are hard to come by, but studies suggest medical emergencies occur at roughly 1 in every 10,000–40,000 passengers. That means if you fly, the odds of a serious medical event happening on your flight are extremely low. In any case, flight crews are trained to handle a range of health issues that might arise, from fainting or dizziness to more serious problems. And with AEDs now on airplanes, if a passenger does collapse from a cardiac arrest, crew (or medically trained passengers) can spring into action immediately.

Yes, having an AED on board can absolutely save lives. Without a defibrillator, a cardiac arrest in flight would likely be fatal unless the plane could land immediately for medical help. With an AED available, however, the outcome can be much better. In fact, survival rates as high as 50–60% have been reported when a passenger in cardiac arrest receives prompt CPR and defibrillation for a “shockable” heart rhythm. (A shockable rhythm can be corrected by a defibrillator shock; about one-third of in-flight cardiac arrests fall into this category.) Essentially, if the heart can be shocked back into rhythm quickly, the person has a much greater chance of surviving until the plane can divert and get them to advanced medical care. There have been numerous cases of lives saved on planes thanks to quick action by the crew and the availability of an AED. It’s important to note that an AED won’t save every life; some cardiac arrests are not due to a shockable rhythm, but having the device on hand vastly improves the odds in those critical first few minutes.

If you have a heart condition or a history of heart problems, the idea of flying might make you nervous. In most cases, having a heart condition does not prevent you from flying, especially if your condition is stable and well-managed. However, it’s essential to consult your doctor before you travel. A medical professional can advise if you’re fit to fly and if any special precautions are needed (for example, additional oxygen during the flight or adjusting medications). Airlines will generally accommodate passengers with medical needs, for instance, they can provide wheelchair assistance at the airport or allow certain medical devices on board. For peace of mind, you might want to inform the airline of your condition ahead of time. We also recommend reading our detailed guide on flying with heart conditions, which covers everything from how long to wait after a heart attack to tips for a comfortable journey. Bottom line: so long as your doctor gives the all-clear, you should be able to fly safely, and remember that modern airplanes are well-equipped for emergencies, with crew training and often an AED on board just in case.

If an AED is on a plane, you might wonder where it’s kept. Defibrillators on aircraft are typically stored in easily accessible locations known to the crew. On most planes, the AED is kept at the front of the cabin or in the galley (kitchen) area, often in a clearly marked compartment or with the first aid kits. Flight attendants know exactly where the defibrillator is; part of their pre-flight safety checks includes confirming the medical equipment is on board and functioning. So if there’s an emergency, the crew can retrieve the AED very quickly. Some larger aircraft may even carry more than one unit (for instance, one at the front and one towards the rear), but this depends on the airline’s policy and aircraft size. As a passenger, you’re not expected to locate the AED yourself; the crew will handle that, but it’s good to know that defibrillators are within quick reach on the plane when needed.

Using an AED on a plane is very similar to using one on the ground, but there are a couple of unique considerations in the air. One difference is that cabin pressure and altitude can slightly affect the performance of medical devices. Airline crews are trained to account for this; for example, they might double-check the device’s settings or be aware of how the thinner air at cruising altitude could influence the equipment. Rest assured, AEDs are tested to work in aircraft environments, and studies have shown they function properly even with the vibrations or background noise in a plane. Another consideration is communication and space: if an emergency happens, the crew will often make an announcement to seek medical professionals on board (there may be a doctor or nurse as a fellow passenger who can assist), and they’ll clear a space, usually by moving passengers from a few rows, to have room to perform CPR and use the defibrillator. The cabin crew coordinate these efforts calmly and efficiently; they practise emergency scenarios regularly.