In a multinational cohort of 77,790 in-flight medical events across 84 airlines, the incidence was 39 per 1,000,000 enplanements (about 1 per 212 flights). Diversion occurred in 2% of cases, most often for neurologic and cardiovascular conditions. The investigation reports: “the overall incidence was 39 events per 1 million enplanements, with 1 event per 212 flights, or 17 events per billion revenue passenger kilometers,” and “aircraft diversion occurred in 1.7% of cases, most frequently due to neurologic (41%) and cardiovascular (27%) conditions.”

Oxygen therapy was the most frequent intervention and used in 41% of events, including 63% of diversions. The equipment kit was accessed in 23% of cases. The study notes: “Oxygen therapy was the most frequent intervention and was used in 31,707 (40.8%) in-flight medical events, including in 842 (63.2%) cases resulting in aircraft diversion… The medical equipment kit was reportedly accessed in 17,789 (22.9%) of cases.” A total of 312 patients (0.4%) died during flight or shortly after landing; most deaths were due to acute cardiac emergencies. “Cardiopulmonary resuscitation was performed in 293 cases (0.4%), with an automated external defibrillator shock delivered in 42 instances… A total of 312 passengers (0.4%) died… with acute cardiac emergencies accounting for the majority of deaths (276 [88.5%]).”

Passenger volunteers with a medical background assisted in 33% of events; physicians were most frequently involved. Volunteers were present in 79% of diversions and 79% of deaths. The authors report that most consultations “proceeded to destination,” with 1,333 diversions, 5,959 transports to hospital, 12,263 treated and released on site, and 312 deaths.

In adjusted analyses, suspected stroke and acute cardiac emergencies were associated with the highest odds of diversion; physician volunteer involvement also tracked with increased diversion odds. Exact wording from the article: “Suspected stroke… and acute cardiac emergencies… were the factors associated with the highest odds of diversion. The involvement of a physician volunteer was also associated with increased odds of diversion.”

The accompanying commentary emphasizes higher-than-prior frequency estimates and the operational profile of diversions: “Alves and colleagues reported an incidence of 39 medical events per 1 million passengers, with 1 incident occurring per 212 flights…” and “aircraft diversion most often involved patients experiencing either acute neurologic or cardiac emergencies, and an onboard volunteer physician was frequently involved in aircraft diversion.” The authors add: “A more uniform approach to managing in-flight medical events would likely be a better option.”

The cohort included 77,790 events reported to a global ground-based medical support center from January 1, 2022, through December 31, 2023. Outcomes were diversion (primary) and hospital transport and in-flight mortality (secondary). Records were created in real time during crew–physician consultations; models used robust standard errors clustered by airline.

Diversion decisions rested with the captain and reflected medical and logistical factors. As the article states, “the final decision to divert rested with the aircraft captain and was influenced by a combination of medical, operational, and logistical factors.”

Exact figures at a glance

• Incidence: 39 per 1,000,000 enplanements; about 1 per 212 flights; 17 per 10⁹ revenue passenger kilometers

• Diversion rate: 2% (reported as 1.7%); leading categories: neurologic 41%, cardiovascular 27%

• Volunteer involvement: medical volunteers 33% overall; physicians most common; present in 79% of diversions

• Mortality: 0.4% (312 deaths); most deaths acute cardiac emergencies (89%)

Disclosures Commentary: Conflict of Interest Disclosures: None reported. Original investigation: See article for full disclosures and license information.

Source: JAMA Network Open Original Investigation, Invited Commentary