Risk Compensation in General Aviation:
The Effect of Ballistic Parachute Systems

Chris Hartman, Lecturer
Engineering and Aviation Sciences Department
University of Maryland Eastern Shore
ENRI International Workshop on ATM/CNS – EIWAC 2010

Background• FAA Certified Flight Instructor• Commercial Pilot (ASEL, AMEL)• Lecturer in the Aviation Sciences Program at theUniversity of Maryland Eastern Shore▫ Teach courses in Human Factors, Advanced
Aircraft Systems, Pilot Ground Schools

Ballistic Parachute Systems• CAPS – Cirrus Airframe
Parachute System• Safety Enhancing Device• To be deployed in anemergency situation:▫ mid-air collisions▫ pilot incapacitation▫ loss of control▫ engine failure over roughterrain▫ engine failure at night• However – these types ofaccidents are statistically rarecompared to other accidentcauses.

2005 Nall Report – Aircraft Owners andPilots Association (AOPA)• Summary, statistics and analysis of General
Aviation Accidents:▫ Mid Air Collisions – “relatively rare”▫ Pilot Incapacitation – “happens very rarely”▫ Failure of Aircraft or Systems – also rare

• More common are “human” causes▫ “Improper action or inaction by the pilot”
 75.5 % of all accidents
 78.6% of all fatal accidents

NTSB Query of Fatal Accidents in Cirrus Design Aircraft
through November 2010

Risk Compensation• The theory that persons adapt their behavior basedon their perceived risk. When humans perceive thatrisk or danger has increased, they will act morecautiously. Conversely, when risk is perceived to beless or a person feels safer, he or she will behave lesscautiously.
▫ Examples: Bicycling Driving Children’s Safety Gear Cell phones and driving
 Aviation?

Risk Compensation cont…
• Hypothesis▫ Pilots, when confronted with hypotheticalsituations, will make riskier decisions when their
hypothetical aircraft is equipped with a ballistic
parachute system than would pilots not equippedwith such a system.

Methods• Two groups of pilots, split randomly, given a preexisting risk assessment tool.

▫ Risk assessment tool developed by Driskill et al. (FAA– 1998)
 Proposed scenarios and gave multiple choice options
 Options had been ranked for risk by SMEs.
 Each pilot could then be assigned a “risk score”
 Safety Deviation Index (SDI)• One group was told they were flying a traditionallyequipped aircraft, the other was told they wereflying an aircraft equipped with a ballistic parachutesystem.
▫ Avionics and all other equipment were the same

Example Scenario

Opinion Questions• The opinion questions instructed pilots to rate thelevel to which they agreed with two separate
statements using a 5-point Likert scale.
• The statements were:▫ I feel that the airplane I am flying, considering its type,condition, and equipment installed, impacts theamount of risk I am willing to accept on a given flight.
▫ I feel that I may be willing to take on greater risks
when flying an aircraft equipped with a ballistic
parachute system than I would in an aircraft without aballistic parachute system.

Limitations• Small sample size (n=76)• Available population• Original tool designed for VFR-only pilots▫ Instrument rated pilots would have “better”
options• Paper Simulation▫ Pilot responses may be very different in the realworld

Safety Deviation Index (SDI)• Higher SDI means riskierdecisions• VFR only pilots:▫ Cirrus pilots made riskier
decisions than Piper pilots▫ Not statistically significant
given small sample size

• Pilots with the greatest flighttime, those reporting morethan 5,000 hours, have thehighest overall SDI score witha mean of 455.2

Opinion Questions 1• “I feel that the airplane I am flying, considering
its type, condition, and equipment installed,
impacts the amount of risk I am willing to accept
on a given flight.”▫ Overall agreement: 3.58.
 VFR-only pilots: 3.36
 Instrument-rated pilots: 3.74

Opinion Question 2• “I feel that I may be willing to take on greaterrisks when flying an aircraft equipped with aballistic parachute system than I would in anaircraft without a ballistic parachute system.”▫ Overall disagreement : 1.68
 VFR-only pilots: 1.97
 VFR-only Cirrus Group: 2.13.

Correlations• Examined SDI scores andopinion question responses forcorrelations with demographicdata• Statistically significant
correlations between Opinion
Question 2 response and Age/
Total Flight Time
• No other significant
correlations

Applications• Training• Decision support systems / automation▫ Must understand decision making in order tosupport it i.e. DECIDE model of decision making▫ Must be “enlightened” by scientific research Research vs. Sales driven• More safety devices may not always be better ?

Future Study• Duplication of paper study with larger sample
size.
• Use of Flight Simulation for enhanced study ofpilot decision making/risk taking