Medical emergencies may not be the first worry on an airline passenger's mind, but illness is a bigger risk than a crash. Each year, more than 100 people are stricken for some health reason while flying on major American carriers, and die in flight or soon after, according to the Federal Aviation Administration.
In most years, that dwarfs the number killed in commercial airline crashes. In 2003, 19 passengers and two pilots died in an airliner crash, and the year before, there were no passenger fatalities.
All planes operated by U.S. airlines that have a flight attendant have been required since last month to carry a defibrillator, a device that shocks a human heart back into normal rhythm during a heart attack. Most American carriers operating big planes have been equipped with them for years.
The defibrillator rule should also reduce the chance that a planeload of people will have to make an unplanned stop unless it is absolutely necessary. Before the devices produce the shock, they provide a diagnosis, determining whether the patient has a heart problem that needs emergency attention, for example. Thus they may help determine that a passenger in distress merely has, say, indigestion.
The airlines say they are not sure how often the defibrillators have saved them from having to divert flights, but acknowledge it is one reason, along with saving lives, that they are happy to carry them.
The new rule -- which also requires that onboard medical kits be upgraded to include saline solution, intravenous injection equipment and additional drugs -- applies to planes weighing at least 7,500 pounds, which generally means those carrying 30 or more passengers. Such planes generally have at least one flight attendant, and flight attendants are trained in first aid. Especially on larger planes, physicians or nurses are often on board as passengers.
The defibrillators are designed so that people with no training can use them; they have instructions attached and give audible prompts. However, health experts recommend that a flight attendant be called to use the device if possible.
When it issued the final rule in April 2001, the FAA pointed out that it had only a general idea of what medical emergencies occur in flight. For example, the agency may know that a passenger was taken off a plane by paramedics, but sometimes does not know whether the passenger lived.
The early evidence is that people with little nor no medical training want to defibrillate first and ask questions later. A study in the New England Journal of Medicine, based on two years of experience at American Airlines, the first major American carrier to equip its fleet with defibrillators, found that flight attendants or medical personnel had used the onboard defibrillators 200 times, including nine times when they were carried into the airport terminal. But the machine detected the condition that the shock corrects in only 14 of the patients.
The machine will not administer a shock unless it determines, by measuring the patient's heart rhythms and comparing those with a database, that it is needed.
At first, flight attendants started using the devices "every time somebody complained of chest pain, indigestion, shortness of breath," said Joan Sullivan Garrett, a critical-care nurse who is the president and chief executive of MedAire, a company hired by about 70 airlines to train flight attendants and to provide doctors on the ground who are available by radio around the clock, within 60 seconds, for consultation.
Garrett said that medical emergencies represented a growing fraction of in-flight problems. "Ten years ago, the reasons planes diverted were because of mechanical issues; today it's because of medical reasons," she said.
"And the airlines are recognizing that the demographics of our population are changing, and the types of problems we're seeing are changing," Garrett added, referring to the higher proportion of older people.
The first life saved by a defibrillator in flight was that of Michael J. Tighe, who suffered a heart attack, his first, on a flight from his home in Boston to San Diego, in November 1998, on American Airlines.
"It was a lucky flight for me," said Tighe, who was then 62 years old. He now has an internally implanted defibrillator.
He said he was probably better off on the plane than he would have been at home. In fact, many travelers can attest that airplanes are better equipped for medical emergencies than many homes and offices.
Tim Cameron, lead first-aid instructor at United Airlines, said that the airline first used a defibrillator to save a life in Tampa, when a woman collapsed while waiting to board a plane and another passenger screamed, drawing the attention of a flight attendant on the plane. A second flight attendant fetched the defibrillator from the airplane. That was in July 2000, Cameron said, adding that he still speaks regularly to the woman who was revived.
Another survivor, Virginia Monahan, 59, was flying home to California last October and changed planes at Denver International Airport. "On my way for a cold beer and a sandwich," she said, she collapsed in the terminal. A United flight attendant came to Monahan's aid. The attendant called a United customer service agent, who grabbed a defibrillator that the airport had stored nearby and used it to revive Monahan.
Experts say the chance that a heart-attack victim will survive declines by about 10 percentage points for each minute before the heart is shocked. With defibrillation, survival rates run about 40 percent, experts say; without, they are near zero.