Helicopters have a bad reputation. Many people unfamiliar with them think that helicopters are a collection of rotating parts, ready to fly apart and cause disaster at any time. Or they have seen a tail rotor shot off by a missile in an action movie and picture themselves spiraling to the ground, victims of inherent instability. People have had to make Judgements about the riskiness of helicopter flight without good information, not because data about helicopter safety doesn’t exist, but because it had never been organized to give a clear picture of the risks of helicopter flight. At
NASA Ames Research Center we undertook to develop such an organization of the data from over one thousand helicopter accidents investigated by the NTSB. [See information below on the study report. ] We began by asking what is the risk of a helicopter accident, and how does that risk compare to risk associated with other modes of travel. When we compared helicopters to airliners, we found that airliners have an accident rate (per departure) about one tenth that of helicopters, no surprise there. We were somewhat surprised that about 10% of accidents involve fatalities for both airliners and helicopters.
This means that fatal accidents are about ten times more likely for helicopters, because accidents generally are about ten times more likely, but the accidents themselves are neither more nor less fatal. Of course, airliners and helicopters are apples and oranges, differing in size, speed, flight environment and pilot population. General aviation aircraft as a group are much more similar to helicopters, minus the rotating parts. And their accident rate is more similar too. In fact the accident rate (per hour) for helicopters and general aviation is nearly identical, about eight accidents per 100,000 hours.
Again about one tenth of ccidents involve fatalities. So maybe smaller vehicles are Just more dangerous. Then what about cars? They are small. And we all know that the most dangerous part of any flight is the drive to the airport. The automobile safety data is measured in miles, not hours, so we used an average speed of 33. 3 MPH to convert it to hours. Then we got a surprise. Not only were cars safer than helicopters, by a factor of twenty, they were safer than airliners, by a factor of two! Of course airliners travel about ten times faster than cars, so their accident rate per mile is about five times lower.
In any case small size does not lead to high risk. When we looked into helicopter accidents in detail, we found that some missions have their own special risks. For example aerial applicators (both fixed and rotary wing) are at greater risk for wire strikes. But mission risks do not account for the higher general accident rate. We looked at accidents as function of helicopter cost. More expensive helicopters show a much lower accident rate than do less expensive helicopters. In fact the rate for very expensive helicopters is nearly the same as that for airliners.
At the other end of the cost spectrum, inexpensive helicopters have the highest accident rate and account or most helicopter accidents. Low-end helicopter accidents are less severe than those that happen to more expensive helicopters. The pilots of more expensive helicopters avoid situations that lead to less severe accidents, or they respond to these situations to avoid an accident. Pilot training, experience and Judgment may be the most important factors in safe flight. Personal and instructional flying account for the bulk of accidents, and these are done mostly in low cost helicopters..
Personal pilots have different types of accidents from professional pilots. The predominant first event of personal accidents is loss of control. For all types of flying for hire, loss of engine power is the most common first event. Personal pilots and students make up the least experienced part of the pilot population, and personal pilots are the most inclined to neglect safety rules and recommendations What it comes down to is that for helicopters, as for other vehicles, the part most likely to cause an accident is the nut behind the controls.
So fly as if your life depends on it, because it does! But the flights can be pricey, and as a recent surge of medical helicopter crashes shows potentially dangerous. According to a report by the National Transportation Safety Board, 2008 saw 12 crashes involving medical helicopters, seven of which were fatal. Medical helicopters have a higher ratio of accidents to number of flight hours than other types of aviation. These potential downsides have some experts concerned that these flights Just aren’t worth it. HEMS [helicopter emergency medical services] is the most dangerous form of helicopter transportation,” says Dr. Jeffrey Rabrich, medical director of EMS and disaster preparedness at St. Luke’s-Roosevelt Hospital in New York. “They often launch in marginal weather and there have been numerous crashes killing all aboard, including the patient. The idea of using helicopters to transport ill patients originated in the military with the Vietnam War. The widespread success of medical helicopters in this setting led to the creation of helicopter programs at many hospitals across the world.
In an attempt to show what effect, if any, that helicopters have on survival for trauma patients, the researchers from Johns Hopkins Medical Center studied over 200,000 victims of a wide variety of trauma including car crashes, gunshot wounds and workplace accidents like Smothers’ by using information contained in a national databank. When they matched patients ith similar characteristics and similar levels of injury, they found a small increased rate of survival in helicopter-transported patients. As for how expensive the service is, in Maryland it costs $5,000 for one such flight.
Using simple math, the authors estimate the cost to save one life is $325,000. But since Maryland has a relatively low operating cost due to the ideal design of their trauma system, in most states the cost per flight is much higher. In some states, the cost per life is over $1 million. Some doctors say the cost is a necessary expense in some areas in which appropriate reatment centers are few and far between. “The greater Houston area is served by just two level 1 trauma centers for over 5 million people,” says Dr. James J. McCarthy, medical director of the emergency center at Memorial Hermann Hospital in Houston.
Yet Dr. Jack Sava, director of trauma at Medstar Washington Hospital Center in Washington D. C. , cautions, “Helicopters are not medical treatments, and they are not magic. They’re Just a fast, expensive way to get to the hospital. ” Location appears to play a big part in how useful these helicopters are. In rural areas, where a few edical centers may be scattered over large areas, helicopters can be a real timesaver. But in urban areas where landing a helicopter can be difficult and distances are short, ambulances are often the faster way to go. It is generally not recognized by the public that a helicopter is not always faster than an ambulance,” says Dr. Amy C Sisley ot Henry Ford Hospita n “Helicopters are otten unable to land at the scene of the injury and must land at a distance in a parking lot or other open space. ” “l would call a helicopter only if the ground transport time exceeds 60 minutes because less than that and the helicopter isn’t saving that much ime,” Rabrich says. “The helicopters time advantage dissipates rapidly as the distance to the trauma center decreases. Many experts think the skill level of the crew and superior equipment on helicopters, rather than speed, is what really makes a difference in care. It is not unusual for a helicopter to have a trauma nurse or even a physician on board, something that an ambulance almost never contains. In Smothers case he was able to receive medications for his injuries that the ambulance on scene could not provide him. “In every instance the capabilities typically available n a helicopter will always be the same or greater than those available in a ground ambulance,” explains Dr.
Michael A. West, professor of surgery at the University of California San Francisco, referring to this study an “apples to oranges comparison. ” He says that instead of helicopters, more emphasis should be placed on packing ambulances with better equipment and enhancing paramedic training. Still, for every argument against the use of these choppers there is a patient like Smothers, who believes that his life was saved by one. Smothers says he is forever grateful for the emergency medical personnel on the helicopter that day.