Weathers Risk

The NTSB recently took a close look at weather-related accidents to see how different pilots manage risk. The results provide clues on avoiding weather-related mishaps.


By Thomas P. Turner

Remember those tedious questions about weather theory on the IFR written?If you blew them off, got them wrong-or otherwise didnt score well on the written-youre more likely to be in an accident. And, regardless of how many hours youve accumulated, youre less likely to bend metal if you earned your certificates at a younger age. Those are just two of the findings of a recent NTSB study that provides fascinating insight into how pilots think about risk.

In its study, the NTSB analyzed data from 72 general aviation accidents that took place in instrument meteorological conditions (IMC) or poor visibility between August 2003 and April 2004. Study managers also contacted pilots of 135 non-accident flights that were operating in the same areas near the time of each crash. All non-accident pilots voluntarily participated in interviews about their flight, providing details of their experience, the aircrafts equipment and their training. The FAA provided written and practical test results for each accident and non-accident pilot to see if there were any correlations between test results and experiencing or avoiding a weather accident.

All information was statistically analyzed to see if any of the variables seem to make accidents or avoidance more likely. NTSB specifically wanted to detect any measurable difference in results based on the following pilot characteristics:

Training background
Written and practical test scores
Prior accident/incident record
Weather briefing source and methods

As always, the NTSB study resulted in several recommendations for changed procedures, or rulemaking by the FAA.

Weather Mishap Trends
The total number of GA mishaps has shown a steady decline in the years leading up to the study, although preliminary figures show an increase in accidents when comparing 2005 to 2004. The trend in accidents occurring in IMC, however, has remained stable, representing five to nine percent of all NTSB-reportable general aviation accidents. Two-thirds of all accidents in IMC prove fatal, so the NTSB (and the FAA) have a great deal of interest in ways to reduce the number of weather-related mishaps.

As a result of several previous weather-accident studies dating back to 1968, the NTSB has recommended that FAA improve collection and dissemination of aviation weather information, pilot training and operations, and ATC procedures. The NTSB reports in its 2005 study that FAA and other agencies have largely adopted these previous recommendations. Yet the mishap trend continued.

Training And Currency
One obvious area the NTSB study examined was pilot training and proficiency.All pilots must receive training on adverse weather and its effects, but have the weather-training rules kept up with todays pilots? Airplanes have become viewed as much more reliable cross-country machines in the years since the FAAs basic weather curriculum was written. Life in general has sped up, making getting there pressures even more demanding for a larger percentage of pilots. New technologies in the cockpit improve weather dissemination en route, but may also encourage pressing on into deteriorating conditions when the same pilot without such equipment may call it a day.

Primary students receive minimal emergency instrument training: Three hours of simulated instrument flight for Private pilot applicants, 10 hours total for Commercial applicants who do not hold the Instrument rating.Recreational and Sport pilot applicants, typically flying airplanes without attitude instruments, need not receive any instrument training, and accept higher flight visibility limitations as a result. Emphasis on training VFR-only pilots is, as it should be, in avoiding deteriorating visibility conditions in the first place.

Currency requirements for Instrument-rated pilots has actually dropped over the years. Remember six, six and six? Formerly, the pilot must log six hours of actual or simulated instrument flight and six actual or simulated instrument approaches in the preceding six months. A revision to FAR 61.57 dropped the six hours requirement some time back, leaving the need merely to log six approaches, holding procedures and intercepting and tracking courses in actual or simulated IMC in the last six months to remain current.Now, theres no stated minimum number of IMC flight hours required. The change ostensibly recognizes that much en route IFR flight happens above or between cloud layers, especially in more capable airplanes. But it has reduced the actual currency requirement. Maintain this bare minimum currency, and an IFR pilot need never again take training on or evaluation of instrument pilot skills.

Getting Weather
Long gone are the days when weather offices dotted the land and most pilot weather briefings took place face-to-face with a certified meteorologist at the weather station on the local airport. Today, the majority of pilots self-brief with a combination of FAA-approved computer-based products and a host of unofficial services ranging from The Weather Channel to in-flight data links. The truly skillful pilot will combine all these, sprinkled with calls to an AFSS for clarification before flight and to Flight Watch for en route updates. Alas, not everyone is a skillful weather pilot.

Consolidation of Flight Service Stations led to personnel cutbacks creating war stories of intolerable telephone hold times and unrelenting calls of stand by when attempting updates in flight. Most briefers today, though well-trained and very well-intentioned, are not meteorologists and are discouraged from interpreting data but merely deliver it. Initial indications are that Lockheed-Martins administration of the newly privatized AFSS network is successfully addressing at least the hold-time issue, but stereotypes die hard and it may take some time before pilots confidence in the system is fully restored.

Meanwhile, were driving toward a future when almost all briefings are automated. Current weather sources still use confusing abbreviations for vital information, inviting greater error on the part of pilots self-briefing for a flight.

The 2005 Study
Against this backdrop the NTSB took a different tack in reviewing mishap records, comparing (as weve said) accidents to other flights flying within 30 miles of the accident site and within 30 minutes of its occurrence. Was it mere luck that one plane went down while another did not? Or was skill involved-skill that can be identified, and better trained?

The studys goal was to identify factors predictive of weather-accident risk for GA pilots. Rare in mishap studies, a control group of non-accident pilots was used to determine the odds of involvement in accidents based on risk factors. So what did the NTSB find?

A summary of the boards findings is in the “NTSBs Findings” sidebar. Other highlights include the following:

Pilot Demographics: Attempting to determine any patterns among accident pilots, investigators gathered pilots personal information. Perhaps dispelling some theories about accidents, pilot age and experience, the study found among accident pilots:

The average had 18 years experience as a pilot.

The average received his/her first pilot certificate at age 35.

About 68 percent were Instrument-rated (compared to 51 percent of the active pilot population).

Four percent held ATP certificates, 32 percent were Commercially certificated, 61 percent held Private certificates, and 3 percent were Student pilots.Flight Hours: The NTSB found it difficult to get accurate information on pilot time except for estimated total time, as reported on pilot medical applications or other documents. The average total flight hours of the accident group was 1300 hours, compared to 2270 hours among the non-accident pilots. When individuals were grouped by experience level, however (<500 hours, 500-1500 hours, 1500-3000 hours, 3000+ hours), the distributions were not found to be statistically significant for the accident and non-accident pilot groups.

Pilot Testing History: The NTSB also looked at whether there is a correlation between FAA written and practical test scores and weather accidents. It found the following:

Accident pilots averaged 86 percent on FAA written exams and an 84 percent pass rate on practical tests.

Non-accident pilots averaged 95 percent on FAA writtens and a 95 percent checkride pass rate.

Purpose Of The Flight: Based on the information available, the NTSB determined that 83 percent of the accident flights were personal in nature, with only 17 percent being flown for pay. Among non-accident flights, 67 percent were private and 33 percent were being operated for compensation.Seventy-six percent of the accident airplanes were owned by the pilot, with 10 percent rented and the remainder owned by the pilots employer or another entity. Comparatively, 56 percent of the non-accident airplanes were owner-flown with 13 percent rented and 30 percent owned by an employer.

The NTSB study confirms many themes expressed by aviation risk management experts. First, the length of a pilots flying career, not necessarily his or her flight hours, is a factor in determining the likelihood of a weather-related accident. Second, training-whether initial or recurrent-figures prominently in this equation. Third, a pilots attitude, as demonstrated through prior accidents/incidents and through a willingness to seek out and understand weather data, will have an impact. These themes are not new to many of us, but they always bear repeating.

Also With This Article
“Errors In Judgment”
“The NTSBs Findings”

-Tom Turner is a CFII-MEI who frequently writes and lectures on aviation safety.


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