An Examination of Types and Causes of Accidents

In Cessna 150 and 152 Aircraft


 
 

Every pilot is interested in safety, or should be.  No one wants to bend or break their airplane.  Most of all no one wants to break their body.  According to the NTSB the greatest enemy to aviation safety is the pilot; in the vast majority of accidents they can find a way to blame the pilot in command.  After reading 425 accident reports involving Cessna 150s and 152s it is difficult to disagree.

 

It has been said “Those who do not study history are doomed to repeat it”.  A thoughtful review of the NTSB accident data base provides a glimpse into some of the details of events that range from minor aggravations to life changing to fatal.   Reading accident reports is dull and at times depressing.  However, the prudent pilot can use these reports to understand and avoid some of the conditions and activities that caused or contributed to many unnecessary accidents.   This summary of the accident data, while not as informative as the basic data, will hopefully provide general information that will contribute to the reader’s safe operation of a Cessna 150 or 152.

       

If the reader is interested in making their own assessment of the details of aviation accidents the NTSB provides a complete and very user friendly data base at http://ntsb.gov/ntsb/query.asp.  Spending some time there will be very instructional.

 

 The following is a summary of data from the NTSB accident data base for Cessna 150s and 152s for the period of January 1, 2003 through December 31, 2008, covering a total of 425 accidents for which probable cause conclusions had been reached.  Accidents for which no probable cause has been established were not considered in the statistical tabulation. 

 

Due to the difference in mission between 150s and 152s data for each model is presented separately.  Additionally a set of consolidated data including all accidents is provided. 

 

In considering the accident rates in Make and Model the accidents that occurred during instructional activities have been eliminated to prevent skewing the results.

 

THE PILOTS

If the pilot is the major cause of accidents it would seem that we should know something about them.  Admittedly the data available is scanty but it is interesting.

 

We can glean a good deal of relevant pilot information from the FAA and NTSB data bases.

Pilot's Age

 

150

152

Consolidated

Youngest

14

17

14

Oldest

87

77

87

Average

48

35

43

Median

48

31

41

 

The average age of 152 pilots is a bit of a decade younger than the average age of 150 pilots.  Also the average experience of 152 pilots is just over 1/3 that of 150 pilots. 

 

The younger average and lower average experience level for 152 pilots is indicative of the fact that the 152s are more active as a primary trainer than the 150s.           

 

It is evident from the age and experience data that the 152 is used more in training than the 150.   The age of the 152 accident pilots is skewed to the younger end of the scale, due most likely to the larger percentage of student pilots.

 

 

 

Experience

 

 

Pilot Experience in Flight Hours

 

150

152

Consolidated

Least

10

0*

0*

Most

32,070

21,225

32,700

Average

1,788

670

676

Median

300

101

200

 

The largest percentage of accidents occurs in the first 200 hours in both models.  It is not surprising to find that almost 50% of 152 accidents occur in the first 100 hours of flying and nearly 2/3ds of all accidents occur in the first 200 hours.  The fewest accidents occur in the 1600 to 2600 hour period with only 6 accidents or 1.4% of total accidents.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Non-Instructional Comparison

When only non-instructional activities are considered there is a dramatic change in both the number and distribution of accidents.  In the first 1000 hours of flying.  The percentage  of accidents changed, period to period, much less dramatically than when instruction was involved.

Activity

150

152

Total

69%

87%

Non-Student

62%

77%

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

As can be seen in the graphs when instruction was involved the percentage of accidents for each model was markedly higher in the first 100 hours.  The significant decrease of the percentage of 152 accidents in the 101 to 200 hour period compared to the 0 to 101 hour period is most likely due to a substantially greater instructional activity in the first period.

 

On the other hand when only non-instructional flying is considered the accident rate occurs in the second hundred hours of flying.  It would not be unreasonable to suspect that this increase is due to pilots moving from the student pilot to privet pilot category.

 

THE INSTRUCTORS

If the pilot is the primary cause of aviation accidents the best hope for improving our record must lie in instruction.   There were a total of 68, just over 16% of total accidents, instructors involved in accidents.  Over all they are of an average age of 39 with an average of 2,914 hours of flying experience. 

 

Age & Experience

Those instructing in 150 average 44 year of age and 4016 hours of flying.  Those instructing in 152 have an average age of 25, with an average of 1,283 hours of flying experience. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A large portion of the accidents with an instructor in the airplane were caused by the CFI waiting too long to salvage a bad situation.  These guys have to walk a very narrow line between being a mother hen and being accused of exercising poor judgment.   

 

Instructors were involved in a total of 8 fatal accidents which produced 14 fatalities.

 

It is apparent from the above data that both age and expense, both for pilots and instructors, make their contributions to safety.  It is seems evident that both judgment and increased skill gained through experience provide the greatest insurance against mishap.

 

Training Matters

Looking at a comparison between the raw numbers of accidents for various certificate levels is a bit tricky with the data available.   With 219,233 privet pilots and 84,566 students out of a population of 597,109 pilots the accident rate as related to training is about what one would expect. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Make & Model Experience

During the first 100 hours of experience in an unfamiliar model aircraft (M&M) there is a substantial increase in the accident rate.   This is true for Cessna 150, 152, 172, 177, 182, 206 and 210 models (The Group).   Due

to the fact that the vast majority of student accidents occur in the first 100 hours of both total time and Make and Model time they have been eliminated from the comparison of accident rates related to total time and M&M time.

 

Aircraft

Total Hrs.

M&M Hrs

Difference

The Group

23%

46%

23%

150-152

10%

36%

26%

 

The table shows the Non-Instructional accident rate (accidents in first 100 hrs / total accidents) for The Group and for only150+152 models for total time and time in M&M.

 

 Since the accidents in M&M time are also included in the total time accidents the difference represents the increased risk attributable to the change to an unfamiliar aircraft

 

Even though few pilots are  “moving up” to 150/152 the increased risk exist for those dealing with a “new” model.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The graph to below demonstrates the importance of increase vigilance when transitioning to any new model airplane, even to the smallest Cessna. 

 

 

 

 

THE ACCIDENTS

The types and causes of accidents are many and varied.  However, 93% (396 of 425) of 150/152 accidents fall into one of four (4) categories; loss of power, loss of control, impacting an object or terrain and stalls.  A large percentage of these accidents are under the control of the pilot in command.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  

 

Accidents can and do occur in any phase of flight.

 Landings are the most worrisome to student and veteran alike.  There are many cases of ATPs coming to grief because of wind and even misjudgment.  The moral to the tail is that no pilot can relax until the wheels are chocked.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

In the NTSB accident reports considered there are 33 probable causes for accident delineated.  However, as Dave Letterman would say here is our own top ten (10) list.  The top ten causes account for 74% (316 of 425) accidents.

 

The many and varied NTSB accident causes can be distilled into five main categories:  Skill, Judgment, Mechanical, Luck and Other ( ie. taking off with empty tanks, etc). 

 

The many and varied NTSB accident causes can be distilled into five main categories:  Skill, Judgment, Mechanical, Luck and Other ( ie. taking off with empty tanks, etc). 

Some are born with an aptitude for flight and some of us have to work and through experience develop the skill(s) required to be a safe pilot.  Obviously landing and dealing with wind require developed skills that take practice, practice, practice.

 

Two accident causes that will surely benefit from practice are the reduction in hard landings, the leading cause at 15% of all accidents, and dealing with the wind, the third most prevalent cause at 12% of all accidents.  Although no data exist to support the impression it appears that a large portion of landing accidents occur on the third or later touch and go.

 

Fuel exhaustion accounts for a whopping 13% of all accidents, second only to hard landings.  This cause surely falls into the “Other” category.

 

Mechanical causes while primarily occurring under the cowl can and do affect any part or system on an airplane. 

 

The Lycoming engine while less susceptible to Carb Ice than the Continental.  However, accidents due to Carb Ice do occur in 152s.

 

The Undetermined category is a bit unsettling in that if one does not know the cause it is difficult to know how to prevent a reoccurrence.   Reading between the lines of the probable cause statements it seems likely that at least some of the unexplained power failure related accidents involve carburetor icing.

 

Judgment, like skill, comes with experience and continuously practicing prudent risk management.  It is alright to back down when things don’t feel right; knowing when to go and when to stay is where judgment comes in to the picture.

 

Luck also plays its’ part, even if it is a minor one.  Every pilot with more than a few hours in his log book can recount occasions when luck, good or bad, was involved in a flight. 

 

When encountering a new (to you) model of airplane remember that for the first 100 hours of so you have again become a student pilot, with all of the joys and challenges that being a student entail.  Be a good student; learn all of the numbers and learn the feel of the plane.

 

We wish you tailwinds, smooth air, and happy landings.

 

 

 

 

 

 

 

 

 

 
  wayne@esisupply.com