Story ID: 
Business Aviation Safety
By: Gordon Gilbert
Caption: In the last 10 years, business aviation safety has improved dramatically.
Word Count: 2895
In the last 10 years, business aviation safety has improved dramatically. During this period, the entire industry has been the subject of numerous equipment and procedural requirements intended to reduce accidents. But have these requirements indeed improved safety or were they just financial, maintenance and procedural headaches for the thousands of operators who were forced to comply? As is the case with most complex subjects, the answers are not always clear and depend in many cases on the specifics of the situation.

One thing is clear: over the last decade, nearly all segments of business aviation flying have become safer. Corporate aviation (defined by safety analyst Robert E. Breiling Associates of Boca Raton, Fla., as all aircraft types flown for business by salaried crews) had its safest year in 2003 in terms of accident rates (accidents per 100,000 flight hours) and its safety record was better than the scheduled airlines’ in every year during the last decade.

For example, although the safety record of fractional operators between 1996 and 2005 (and so far this year) was exemplary, the FAA saw fit to require fractional operations to fly under essentially the same safety requirements as Part 135 commercial operators or meet an entirely new set of FARs known as Part 91 Subpart K.

Has the accident rate changed significantly since Subpart K went into effect in 2003? Not really. To date, there still has been no fatal accident involving a fractionally owned airplane, and the sector’s accident rate (incidents per 100,000 hours) last year registered as the best across all segments of turbine-powered business aviation. Subpart K has served to equalize operational requirements for fractionals with the limits of Part 135–such as for runway distance, look-see approaches, duty time and weather-reporting requirements. Previously, fractional operators had been permitted to operate under the less stringent requirements of Part 91.

In addition to making fractional operators answer to a higher authority–which might or might not reduce accidents in this segment–the rule change did accomplish one thing Part 135 operators had been craving and which had little to do with safety. Traditional charter operators believe Subpart K leveled the economic playing field. Before Subpart K, air-taxi operators groused about alleged unfair competition created solely by the fact that fractional operators could operate under more lenient rules.

Equipment Mandates

The 2004 mandate for emergency locator transmitters (ELTs) on transport aircraft resulted from an act of Congress in response to a single fatal crash of a Learjet 35 on Christmas Eve 1996 in IMC on approach to Lebanon Municipal Airport in New Hampshire. Searchers gave up trying to locate the wreckage, which finally was found two years later completely by accident.

Starting on July 1, 2008, all airplanes operating internationally will need to carry at least one emergency locator transmitter, according to a proposed standard from the International Civil Aviation Organization (ICAO). The proposal also states that beginning July 1, 2008, “automatic” (406-MHz) ELTs must be carried on all international operations of both commercial aircraft authorized to seat 19 passengers or fewer and private aircraft with any number of passenger seats that obtain their certificate of airworthiness after that date.

Congress (pushed by the lobbying efforts of then avionics maker Sundstrand) was also responsible for the 1974 mandate for airlines to equip their aircraft with ground proximity warning systems (GPWS). But controlled flight into terrain (CFIT) accidents continued until the advent of enhanced GPWS in 1996.

The technological upgrade in ground proximity warning devices came after an American Airlines 757 crashed in Cali, Colombia, in 1995. It hit a mountaintop on its approach to the airport, killing 160 of the 164 on board. Investigators believed that a more sophisticated warning device would have given the pilots an earlier alert, adding a few seconds for them to take actions to avoid the crash.

There have been no CFIT crashes by airplanes equipped with enhanced systems–either the enhanced GPWS from Honeywell, or terrain awareness and warning systems (TAWS) from several other manufacturers.

That statistic, combined with a barrage of recommendations over the years from the NTSB, prompted the FAA in 2001 to extend the requirement for TAWS beyond Part 121 airline transports to all FAR Part 91 and 135 turbine aircraft configured for six or more passenger seats.

The mandate became effective for airplanes manufactured after March 29, 2002, and on March 29, 2005, for airplanes built before March 29, 2002. Those compliance dates were too late for the crew of a 1980 Learjet 35 that crashed into a mountain on Oct. 24, 2004. According to NTSB investigators, the air-ambulance flight crashed into Otay Mountain at 12:30 a.m., about two minutes after taking off from Brown Field near San Diego. The crew took off under VFR, intending to pick up their IFR clearance in the air. The two pilots and three aeromedical staff were killed. Said the Safety Board in its May 23 final report: “The airplane was scheduled to have a terrain awareness and warning system (TAWS) installed in January 2005”–only about three months before the March 29 compliance deadline.

TCAS and Mode-S

While TAWS addresses the issue of airplanes flying into terrain, traffic alert and collision avoidance systems (TCAS) are intended to help prevent airplanes from hitting each other–both on the ground and in the air. Since Jan. 1, 1996, TCAS has been required on Part 135 turbine airplanes configured for 10 or more passenger seats. Part 135 operators also have the option of equipping with the more sophisticated TCAS II (required in larger aircraft).

Unlike TAWS, TCAS is not required in the majority of Part 91 turbine aircraft. But, starting Jan. 1, 2005, turbine airplanes with an mtow exceeding 12,500 pounds or having between 19 and 30 passenger seats must have TCAS II or ACAS (TCAS II with Change 7). Since March 31, 2005, upgraded mode-S elementary surveillance transponders (which contain an aircraft registration ID number downlink) have been required for operations in European Civil Aviation Conference airspace.

Meanwhile, the FAA has withdrawn its decade-old proposal to rescind its requirement for mode-S transponders and adopted a new rule that will end the hundreds of mode-S installation exemptions currently in effect.

As a consequence of the proposal’s being withdrawn, beginning next March 1, Part 121 and 135 operators will no longer be exempted to fly without a mode-S transponder. No new exemptions will be granted after that date, though mode-A or -C transponders can continue to be used until they can no longer be repaired, after which they would have to be replaced with a permanent mode-S unit.

When the FAA, in 1996, proposed to rescind the mandate to install mode-S transponders (except on aircraft equipped with TCAS II), the agency was inundated with requests for exemptions, as operators anticipated the mode-S requirement would be withdrawn.

Some safety experts believe that the potential for midair collisions is raised in VMC (conditions when most midairs occur) because there is no requirement for transponders on aircraft operating VFR outside Class A, B or C airspace. To date, the NTSB and FAA have not addressed this. Maybe they will after they complete their investigation into August’s (nonfatal) midair between a VFR glider and an IFR Hawker 800XP. At press time, though, there was no official word that absence of a transponder was a factor in the accident.

Also at press time, the investigation had only just started on the September 29 midair in Brazil between a 737 and a Legacy 600. The investigation will no doubt look into the part that TCAS might have played.

One of the next major upgrades in the ATC system that promises to improve safety, as well as increase operational efficiency, is ADS-B. Although it will be several years before its use is widespread across the National Airspace System, some limited use so far appears to be proving its value. In these limited evaluations, aircraft equipped with ADS-B have had a lower accident rate than nonequipped aircraft, according to the FAA.

From 2000 through 2005, the rate of accidents for ADS-B-equipped aircraft dropped 49 percent, the agency said. These statistics come mostly from the experience of operators in Alaska, the only region in the U.S. in which ADS-B is used. Soon, however, the technology will be approved for use in the Gulf of Mexico, primarily by offshore helicopter operators.

More Regs Do Not Always Mean Better Safety

It might be assumed that the stiffer the operational requirements, the safer the operations. There is some evidence that supports that assumption. For example, accident statistics indicate that Part 121 air carriers have the lowest accident rate of all segments, but that is not the case when accidents for business jets flown under the more restrictive Part 135 are compared with accidents befalling business jets flown by salaried pilots under Part 91. Why is that? In many respects the rates of exposure at the most dangerous times–takeoff and landing–are more frequent for Part 135 operators than for Part 91 operators. However, the landing and takeoff frequency for air taxis is similar to that for fractionals, yet the latter have fewer incidents and accidents.

In addition, even the toughest rules can sometimes be difficult to enforce when rulemakers are often relying on aircraft owners and operators to follow the honor system. For example, investigations into several high-profile air-taxi accidents in the last few years have revealed confusion for safety investigators and regulatory officials trying to pinpoint who exactly was the entity in command and control of the flight, as well as discovering FAR and DOT violations by noncertified businesses ostensibly holding themselves out to be operators.

Addressing Icing Accidents

NTSB recommendations and FAA rulemaking often result from accident and incident investigations that indicate a trend or commonality–by the circumstances of the accident, operational certificate or type of aircraft. General aviation turbine airplanes over the last decade presented some highly visible examples, such as the number of accidents involving Cessna Caravans and Mitsubishi MU-2s, particularly in icing conditions.

In the case of the MU-2, there have been two major FAA events in the past decade–a special safety review that got under way last year to address all aspects of flying the twin turboprop and a 2003 operational AD to address specifically MU-2 icing accidents.

More stringent training requirements for MU-2 pilots will result from the review of the turboprop twin. For Part 135 operators, the additional requirements will become part of their FAA-approved training syllabus. For Part 91 operators, which cover the vast majority of MU-2Bs, a special FAR will be promulgated through the usual rulemaking process. The safety review is still under way so its results cannot be evaluated yet, but the 2003 operational AD is a different story.

That directive (AD 2003-22-07) was unusual because instead of requiring an aircraft repair or modification, it is used to mandate pilot training–specifically, MU-2 pilots must receive icing training regularly. Since that AD came out, there hasn’t been a single MU-2 icing accident. However, non-icing MU-2 accidents continue to occur and perhaps the safety review, once put into action, will help stem these mishaps.

The FAA might take a slightly different tack to reduce icing accidents in the Caravan turboprop single. Pilot training is expected to become a part of the FAA-approved airplane flight manual (as it is for the MU-2), but at press time an AD was not in the works. Caravan charter operator Linear Air in late August said that its industry contacts mentioned not only a mandatory Cessna icing training program but also that Cessna has conducted Caravan icing tests and will release new performance charts and procedures before year-end.

Icing accidents in the U.S. and abroad in recent years involving the Challenger also led to an AD. Although the accidents were attributed to the flight crew’s failure to ensure that the jet’s wings were completely free of ice or frost before takeoff, the NTSB concluded that “for many years we have been dealing with the fact” that aircraft such as the Challenger with so-called “hard wings [that is, those without leading-edge devices] have been found to be more susceptible to the effects of icing.”

The directive (AD 2005-04-07), issued early last year, requires that operators of all U.S.-registered Challenger 600s, 601s and 604s and Canadair Regional Jets incorporate flight manual revisions to ensure that before takeoff the “wing leading edge and upper wing surface are completely free of ice, frost, snow or slush.” In addition to a visual inspection, the ADs require a “tactile means” to identify potential contamination. The FAA directive followed an identical AD from Transport Canada.

As a result of its investigation of the Nov. 28, 2004 fatal takeoff accident involving a Challenger 601 in Montrose, Colo., the NTSB, in December 2004, issued a special alert advising pilots of all aircraft about the detection and effects of ice accumulation on the wing.

In the aftermath of four dual flameouts involving P&WC JT15D-powered Beechjets, the NTSB late last month issued an urgent recommendation to help prevent further incidents on Beechjets and a broader recommendation calling on the FAA to work with engine and airplane OEMs to develop an ice detector for new engines, as well as for retrofit. The NTSB believes that many pilots are not aware of the risk ice crystals pose at high altitude.

Overruns Abundant

Turbine business aircraft accidents involving icing, loss of control and botched instrument approaches in IMC have caused the most loss of life over the past 10 years, according to data provided by safety analyst Breiling Associates.

But one of the most common mishaps for private and commercial aircraft is the landing or aborted-takeoff overrun. There were 44 runway overruns last year involving air-transport aircraft, according to the International Federation of Air Line Pilots’ Associations. The data served to underscore the group’s crusade to get runway-end safety areas or arrester beds on runways at all major airports worldwide.

Although there are many overruns that are not investigated by the NTSB because they do not incur substantial damage or serious injury, there have been some spectacular ones that have caused fatalities and resulted in new requirements for operators of both aircraft and airports.

Failure of ground spoilers to deploy caused at least six nonfatal overruns involving early models of the Raytheon Premier I between 2002 and 2004. These accidents led to an AD requiring Premier I operators to temporarily replace existing landing-distance and landing-weight charts in the AFM with charts that reflect the increased landing distance without the lift-dump spoilers deployed. Since Raytheon Aircraft incorporated a fix, there have been no reported overruns involving Premiers.

The February 2005 crash of a Challenger 600 after it overran a runway at Teterboro Airport in New Jersey got the ball rolling on the government’s investigation into improper charter operations. And the overrun last December of a Southwest 737 at Chicago Midway Airport led to a controversial new requirement for commercial and Part 91K operators when computing landing distance–the so-called 15-percent rule, which is scheduled to go into effect before year-end.

However, compliance with the 15-percent requirement has been delayed, since some business aviation trade groups challenged the notice as being ill-conceived and illegal because it didn’t go through the notice of proposed rulemaking process, complete with a public-comment period.

Overruns are included in the few accidents involving fractional operators, such as the May 2, 2002 overrun of a NetJets Citation in Leakey, Texas. The airplane touched down about 2,100 feet beyond the landing threshold, leaving just 1,875 feet in which to stop. The two crew and four passengers escaped injury, but the jet was destroyed in the post-crash fire. The NTSB in June released the probable cause, saying the “pilots failed to land the aircraft at the proper touchdown point to allow adequate stopping distance.”

This and other overruns have led the FAA to take action to help prevent damage and injuries from overruns. Part 139 (certified) airports are now mandated to construct 1,000-foot safety areas or barriers at the ends of their main runways, where possible. Some airports have had to shorten runways to accommodate safety areas. There is no requirement for safety overruns or barriers at most general aviation airports.

Engineered Materials Arresting Systems (EMAS)–designed for runways that do not have enough space for 1,000-foot-long safety areas–are being installed at several airline and nonairline airports. To date, EMAS has been credited with preventing injury and aircraft damage in four incidents, including a Falcon 900 overrun on July 17 at Greenville Downtown Airport, S.C.