What Happens If You Fall Ill on a Plane? Global Rules on Diversion, Doctors and Costs

How common are in-flight medical emergencies

More than 3.5 billion passengers travelled on commercial aircraft globally in 2022, and medical emergencies occur on approximately 1 in every 604 commercial flights, according to data cited by the US Federal Aviation Administration and the CDC. The most common issues are syncope or presyncope (fainting or near-fainting), respiratory symptoms, and nausea or vomiting. For roughly 90 percent of these emergencies, the aircraft continues on to its original destination without incident. The death rate for medical emergencies on commercial flights is approximately 0.3 percent, a figure that reflects both the rarity of the most serious events and the effectiveness of onboard equipment, ground-based medical support, and volunteer responders in managing the rest.

Who actually decides to divert the plane

Only 4 to 7 percent of in-flight medical emergencies result in an actual diversion to an alternative airport, and that decision is never made by a doctor on board or by the ill passenger. It rests solely with the pilot in command, who typically consults ground-based emergency medicine physicians contracted by the airline, such as MedLink (based in Arizona) or Stat-MD (based in Pennsylvania). These services communicate with the cockpit via satellite phone, radio, or ACARS messaging, and a ground physician will often take primary responsibility for recommending whether a diversion is medically necessary. Even so, the final call weighs factors well beyond the medical picture alone, including the aircraft's landing weight and remaining fuel, weather at candidate airports, and whether a nearby airport actually has the runway length and medical infrastructure to help. A volunteer doctor on board can offer a strong recommendation to divert, but cannot compel the pilot to do so.

Do doctors have to help? The country-by-country answer

Whether a healthcare professional is legally obliged to respond to an in-flight emergency at all varies significantly by country. In the UK, the US and Canada, there is no legal duty for a doctor, nurse or other medically qualified passenger to volunteer, although many feel a strong ethical obligation to do so. Australia and a number of European countries take the opposite approach, imposing a legal duty on physicians to act. In the US, the Aviation Medical Assistance Act of 1998 protects volunteers from liability unless there is gross negligence or wilful misconduct, encouraging medical professionals to step forward without fear of being sued for a good-faith effort. That protection applies clearly to domestic US flights and most claims involving US carriers or residents, but for other international flights, which country's law actually governs liability is genuinely unclear. It may depend on where the aircraft is registered, where the incident physically occurred, or the responder's own country of licensure. Good Samaritan protections generally also require that no payment is received for the assistance and that the flight crew formally requested the volunteer's help.

Real cases: from a seizing infant to a mid-air birth

Real incidents illustrate how varied these situations can be. In one widely reported 2014 case, an infant on a US Airways flight from Tampa to Phoenix suffered a seizure and stopped breathing; two passenger doctors performed CPR until the child began breathing again, and the pilot diverted the flight to Houston as a precaution. In-flight births are rarer still but follow a similarly structured response: cabin crew use a standardised communication format (sometimes referred to as NITS - nature, intentions, time, special instructions) to alert the flight deck, who may divert to the nearest airport with suitable medical facilities if delivery appears imminent before landing. Recent examples include a Ryanair flight from Brussels diverting to Limoges in 2025 and a Turkish Airlines flight between Istanbul and Chicago in 2021. Separately, a 2020 English court case centred on a 5-month-old infant whose in-flight illness caused a diversion and a subsequent 23-hour delay on the return leg - a case that turned out to matter as much for air passenger compensation law as it did for the medical emergency itself, covered in full in the companion piece on claiming compensation after a medical diversion.

Who pays for an emergency diversion

The direct cost of an emergency diversion is substantial, estimated at anywhere from around $3,000 for a short regional diversion to $500,000 or more for a long-haul wide-body aircraft, driven by extra fuel burn, landing and handling fees at an unplanned airport, and the cost of rebooking or re-routing every other passenger on board. That cost is absorbed by the airline, not billed to the passenger whose illness triggered it. This does not mean airlines are free from liability, however. In Yahya v. Yemenia-Yemen Airways, a passenger warned the crew he could die without immediate medical attention; the crew declined to divert to a nearer airport, and the airline faced potential liability for that decision. In Starks v. American Airlines (2019), the family of a passenger who died of a pulmonary embolism during a flight sued the airline over medical equipment, including a blood pressure monitor and defibrillator, that allegedly failed to meet FAA specifications. Both cases show that while airlines have wide operational discretion over diversion decisions, that discretion is not entirely without consequence.

Children in the air: a different risk profile

Children experience a meaningfully different risk profile in the air. A large study of in-flight medical events involving children and adolescents under 19, drawn from ground-based medical support records across 77 commercial airlines, found the most common issues were gastrointestinal complaints (35.4%), infectious symptoms (20.3%), and neurological issues (12.2%), with nausea or vomiting, fever and chills, and acute allergic reactions the leading specific causes. The large majority, 82.9 percent, resolved in flight without needing further care on landing, and only around 0.5 percent of pediatric in-flight medical events led to an aircraft diversion, compared with 4 to 7 percent across all in-flight emergencies generally. Separately, in-flight injuries (as distinct from illness) disproportionately affect infants held on a parent's lap rather than seated in an approved restraint, accounting for 35.8 percent of injury cases versus 15.9 percent of other medical events - a reminder that turbulence and hard braking on landing pose a real, if statistically small, injury risk to unrestrained infants regardless of how healthy they are at boarding.

What this means if you're the ill passenger, or just a fellow traveller

For the person who actually falls ill, the practical reality is that crew and any volunteer responder will assess and try to stabilise the situation in consultation with ground-based medical control, and the final decision on whether to divert is made in their medical interest, not something they can request or refuse. They are not billed for the cost of a diversion made on their behalf. It is also worth knowing that airline cabin crew are not bound by clinical confidentiality rules in the way a treating doctor or hospital would be, so relevant details may be shared with the flight deck and ground medical services as a normal part of managing the emergency. For everyone else on board, the diversion decision cannot be appealed or reversed by other passengers, however inconvenient the resulting delay - though what those fellow passengers are entitled to as a result of that delay, regardless of who caused it, is a separate question covered in the companion piece on flight-diversion compensation.

Frequently asked questions

How often do medical emergencies happen on planes?

Roughly 1 in every 604 commercial flights, according to FAA and CDC data, though only 4 to 7 percent of these result in an actual diversion.

Can a passenger or doctor force a plane to divert?

No. A doctor or fellow passenger can only recommend a diversion; the final decision always rests with the pilot in command.

Are doctors legally required to help during a flight?

Not in the UK, US or Canada, though many feel an ethical duty to. Australia and several EU countries do impose a legal obligation on physicians to respond.

Who pays for a flight that diverts due to a medical emergency?

The airline absorbs the cost, which can range from a few thousand pounds to several hundred thousand, not the ill passenger.

Are children more or less likely to cause a flight diversion than adults?

Far less likely - about 0.5 percent of pediatric in-flight medical events lead to diversion, compared with 4 to 7 percent for adults overall.