Brief Report

injury patterns related to ultralight aircraft crashes

Scott B. Davidson MD ^a,?, Paul A. Blostein MD^a, Sheldon B. Maltz MD^a,

George England MD^b, Thomas Schaller MD ^c

^aTrauma Surgery Services, Bronson Methodist Hospital, Kalamazoo, MI 49007, USA ^bNeurosurgical Services, Bronson Methodist Hospital, Kalamazoo, MI 49007, USA ^cTrauma/Orthopedic Services, Bronson Methodist Hospital, Kalamazoo, MI 49007, USA

Received 9 September 2008; revised 2 December 2008; accepted 2 December 2008

Abstract

Purpose: Flying ultralight aircraft is a popular and growing form of recreation. However, there is considerable risk involved in this activity. This study was undertaken to catalogue the injury patterns, surgical procedures, and complications of patients involved in ultralight crashes in southwest Michigan. Basic procedures: The trauma registry at Bronson Methodist Hospital was used to retrospectively identify all ultralight crashes between 1983 and 2006. All patients who survived to the hospital were included in the study.

Main findings: Seventeen patients were identified, all males with a mean age of 48.5 years. Mean injury severity score was 23, with all patients sustaining multiple injuries. Mortality was 17%. Lower extremity fractures were most common, followed by head/neck/facial injuries. Orthopedic extremity procedures were most commonly performed.

Principal conclusions: Ultralight crashes result in complex high-energy injury patterns. These patients are likely to require the resources of designated trauma centers. Increased oversight may help prevent ultralight-related injuries.

(C) 2010

Introduction

Flying ultralight aircraft is a very popular and growing form of recreation throughout the world. It is estimated that there are more than 20 000 ultralights in operation in the United States and Canada alone. Some of the popularity of the sport is related to the relatively modest cost compared to conventional flying. There are approximately 30 different ultralight models ranging in price from $5000.00 to

$10 000.00. Most ultralights can be assembled by their

* Corresponding author. Tel.: +1 269 341 6022.

E-mail address: [email protected] (S.B. Davidson).

owner, which adds to the interest of owning and flying ultralight aircraft while maintaining its affordability.

The US Federal Aviation Regulations definition of an ultralight aircraft uses the following criteria: (1) must have only 1 seat, (2) may be used only for recreational or sport flying, and (3) do not have an airworthiness certificate; and

(4) powered ultralight must possess the following character- istics: have an empty weight of less than 154 lb (115 kg), have a maximum fuel capacity of 5 gallons (19 L), have a top speed of 55 knots (102 km/h or 63 mph) at full powered air speed, and have a power-off stall speed of 24 knots (45 km/h or 28 mph) calibrated air speed. In addition, persons operating these crafts must avoid densely populated areas, bad weather, and night flying [1].

0735-6757/$ - see front matter (C) 2010 doi:10.1016/j.ajem.2008.12.002

Ultralight crashes 335

The development of ultralight aircraft has evolved through 3 generations of advancement [1]. The first generation consisted of hang gliders with small engines added for self-launching. The wings were braced by wires, and steering was accomplished by shifting the pilot’s weight onto the wing. The second generation of ultralights was designed as powered aircrafts but still used wire bracing and single surface wings. The 2-axel control system was introduced, operated by stick (yoke), which controlled the elevator (pitch) and the rudder (yaw), but did not allow direct control of banking (roll). The third generation started using spoilers on the tip of the wings and pedals for rudder control. The pilots of ultralight aircraft have been described as sport enthusiasts “wanting all the thrills of flying with none of the hard work, training, and maturity required to become a professional or military pilot” [2].

The causes of ultralight crashes are most frequently due to engine failure, stalling, and pilot error. These types of aircrafts have a tendency to go into a direct vertical dive that the pilot is unable to correct. The aeronautic explanation is that the wing in the ultralight may conform to different configurations that result in the “Nose Over Dive In” [3].

Several articles are published exploring the frequency and mechanism of ultralight crashes; however, there is very little data published describing injury patterns as a result of these accidents in the United States. This study was undertaken to catalogue the injury patterns of patients involved in ultralight crashes in southwest Michigan. This appears to be the largest descriptive series to date identifying extent and pattern of injuries in ultralight aircraft crashes.

Materials and methods

Bronson Methodist Hospital is a level I trauma center located in Kalamazoo, MI. As a regional trauma center, we receive referrals from 9 surrounding counties encompassing 5338 square miles. The population of this predominately rural area is approximately 1 million people. There is an additional level I trauma center within this catchment area. After receiving institutional review board approval, we utilized our trauma registry (Trauma One, Lancet Technol- ogy, Inc, Boston, MA) to retrospectively identify all ultralight crashes between 1983 and 2006. The trauma registry serves as a database and includes all patients with International Classification of Diseases (ICD) codes from 800 to 959 who are admitted to the hospital. The trauma registry captures data on patients admitted to the hospital and does not include patients who die at the scene, in transport, or are dead on arrival. Inclusion criteria encompassed all patients who were admitted with a mechanism of injury from ultralight aircraft crashes. Exclusion criteria included patients injured in commercial and private licensed aircraft, nonmotorized hang gliders,

Table 1 Demographics

and airfoils. Data collected included gender, injury severity score (ISS), hospital length of stay , ventilator days, disposition, procedures performed, mortality, and complica- tions. Injuries were categorized according to body region. Demographic data were summarized using descriptive statistics. Pearson correlation analysis was conducted to determine the relationship among the variables. An equivalent nonparametric correlation test was performed on end points whose value distribution did not satisfy the parametric test assumptions. A 5% level of significance was used to evaluate statistical significance in all analyses.

Results

Seventeen patients were identified from 1983 to 2006. Patient demographics revealed that all were male (Table 1), with a mean age of 48.47 years (SD +- 13.83). The mean ISS was 23 (SD +- 14.15), with all patients sustaining multiple injuries, some to the same body region. Average LOS was

14.17 days (SD +- 14.49), and mean ventilator days was 5.4 (SD +- 8.41). Three patients expired (17.6%), with ages 43, 71, and 74 years. Eight were able to be discharged to home, 5 to rehabilitation and 1 to a nursing home. None of our patients were documented to be under the influence of alcohol or Illicit substances at the time of their crash.

Six patients sustained 9 Traumatic brain injuries (TBI) (Fig. 1). Eleven patients incurred 18 spinal injuries including 4 with Neurological deficits; 2 of these patients were quadriplegic. Ten patients sustained 22 injuries to the head, face, or neck, including fractures, lacerations, and soft tissue wounds. There were 5 patients who sustained 8 chest injuries, 3 who had abdominal injuries, and 5 who had pelvic fractures. There were 9 upper extremity injuries and 38 lower extremity injuries. There were 10 Open fractures and 1 Vascular injury that were documented in this group of patients.

A total of 44 operative procedures were performed (Fig. 2). Most of the operative procedures were open reduction internal fixation of extremity and spinal fractures. Two procedures were performed by interven- tional radiology, including 1 Inferior vena cava filter placement, and an attempt at embolization of an iliac artery injury. Fourteen procedures were performed at the bedside

Mean		SD	Range
Age	48.47	+-13.83	21-74
ISS	23	+-14.15	1-50
LOS	14.17	+-14.49	1-48
Vent days	5.4	+-8.41	0-30
n = 17 all male patients.

336 S.B. Davidson et al.

Fig. 3 Complications (n = 16).

Fig. 1 Frequency of injury pattern (n = 112 injuries).

including tracheostomy, feeding tube placement, chest tube insertion, thoracentesis, intracranial pressure monitor placement, and multiple laceration repairs.

In our patient population, there were 16 complications (Fig. 3), of which 50% were respiratory in nature. Three patients acquired 4 cases of pneumonia, and 1 patient developed adult respiratory distress symdrome (ARDS). In addition, there was 1 case each of bronchitis, sinusitis, and acute respiratory failure requiring reintubation. Of all the fractures that occurred, there were only 2 Wound infections from complex open fractures. Additional complications included a single incidence each of renal

Fig. 2 Operative procedures (n = 44).

failure, stress gastritis, delirium, ileus, Arterial line infection, and clostridium difficilE colitis.

Discussion

This is the largest study to date of ultralight crashes documenting injury patterns and hospital care in the United States. The demographic data in this study revealed a pattern of severe multisystem injury, consistent with previously published reports [3,4]. However, as a referral center, it is likely that only the most severely injured patients were transferred to our institution. Because we were unable to capture data from the scene of the ultralight crashes, this may result in some degree of selection bias.

All patients were male and hospitalized for an average of

2 weeks, with a mean requirement of 5 days on the ventilator. The patterns of injuries sustained in this study were diverse and consistent with a high-energy mechanism of injury. Chalmers et al [4] documented in a study from New Zealand that most fatalities have involved injury to multiple body regions, with at least 1 injury being serious enough to cause death in 48% of cases. In his study, among patients who survived to hospitalization, the lower extremities were involved in 23 % of the cases. In our series, 34% of the patients sustained lower extremity injuries. The series by Chalmers et al [4] noted 20% of their patients to have spinal injuries, which was similar to the 16% incidence in our study group. Although head and facial injuries occurred in 11% of the population in the study by Chalmers et al [4], our incidence of combined facial and head injuries was 20%.

Ultralight aircraft fly at speeds in excess of 55 knots (63 mph). The pilot is seated in an open unprotected environment. Depending on altitude and speed, energy forces transmitted to the pilot may be severe. In this study, it

Ultralight crashes 337

may be postulated that the high incidence of lower extremity fractures is the result of pilot positioning when striking the ground. Patients surviving to the hospital sustained the greatest forces to the lower extremities, whereas nonsurvi- vors likely sustained forces to the head, chest, or abdomen as reported by Chalmers et al [4].

In our study, we had 3 deaths of 17 patients, with a mortality rate of 17.6%. Two of these fatalities were aged 71 and 74 years, respectively. In addition, more than half of the pilots were greater than 50 years of age. These patients will have increased comorbidities complicating their care, unlike the commercial or military pilots who must meet strict fitness requirements.

One might expect a high infection rate in these patients because most ultralight crashes occur in open, rural areas. Soil may likely contaminate these wounds, as well as fuel and oil from the aircraft itself. Remote areas and difficult terrain may cause delays in discovering the ultralight crash victim and prolong time for emergency medical services to reach the crash scene. Stabilization and transport to the nearest medical center are often many miles away and contribute to prolonged time from injury to treatment for these survivors. Our patients required 44 operative proce- dures, most of which were orthopedic. However, there were only 2 wound infections in this group of patients for an overall infection rate of 4.5%. Aggressive washouts and staged reconstruction of all open fractures may have reduced our complication rate.

Of the 16 complications seen in our study population,

8 were respiratory in nature. Four of these were pneu- monias in ventilated patients, 3 of which were treated in the era before the incorporation of ventilator-associated pneumonia protocols.

There were several limitations to this study. Selection bias is innate to data gathered at a regional referral center. Retrospective study design and the prolonged length of time used to gather our patient data had inherent limitations. Finally, changes in surgical critical care over the 23-year study period, such as ventilator-associated pneumonia protocols, deep vein thrombosis prophylaxis,

and strict glucose control protocols, may have affected patient outcomes.

Ultralight injuries continue to present to emergency departments in southwest Michigan and most likely in other areas throughout the United States. This study revealed that ultralight crashes may result in severe injuries and was consistent with high-energy blunt trauma. Given the restrictions on flying ultralight aircraft, these patients are likely to present to smaller Rural hospitals. Multisystem injuries predominated in our study and required dedicated trauma and subSpecialty surgical care. The data from this study would support the prompt stabilization and transfer to designated trauma centers able to provide a higher level of care. Although not the primary focus of this study, there appears to be minimal regulation in design, construction, and operation of ultralight aircraft. Given the inherent danger of this sport, increased oversight may help to prevent ultralight aircraft-related injuries.

Acknowledgments

The authors thank Ms Kuanwong Watcharotone, MS, for her assistance with statistical analysis, and Sheri Vanden- Berg, BS, for manuscript preparation and editing.

References

1. Wikipedia contributors. Ultralight aviation. Wikipedia, The Free Ency- clopedia. Available at: http://en.wikipedia.org/wiki/Ultralight_aircraft [Accessed September 4, 2007].
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3. Zwimpfer TJ, Gertzbein SG. Ultralight aircraft crashes: their increasing incidence and Associated fractures of the thoracolumbar spine. J Trauma 1987;27(4):431-6.
4. Chalmers DJ, O’Hare DP, McBride DI. The incidence, nature and severity of injuries in New Zealand civil aviation. Aviat Space Environ Med 2000;71:388-95.