In 1966, during testimony
before the U.S. House Committee on Interstate and Foreign Commerce, Consumer
Advocate Ralph Nader rapped the back of a latched safety belt buckle on
his knee. It came apart. With that demonstration, the terms
“inertial release” and “inertial unlatch” entered the auto safety lexicon.
So did the term “parlor trick.” They have been hurled back and forth
at each other by automakers and safety advocates ever since.
Nader’s demonstration sought
to show that, in a crash, a safety belt buckle can unexpectedly unlatch
- at the very moment the car’s occupant most depends on its proper functioning.
Automakers responded with derision. General Motors said Nader’s charge
was “without foundation.” A Ford vice president called it “ridiculous”
and the Nader demonstration a “parlor trick.” They contended
then, and contend still, that it does not represent anything that occurs
in “real world” crashes, arguing that the tension of taut safety belts
prevents their unlatching during a crash.
Crash tests, laboratory tests,
mathematical analysis and other evidence demonstrate convincingly otherwise:
safety belt buckles can and do unlatch in crashes.
1978: NHTSA Ignores Evidence #1
After an investigation team
reported to the National Highway Traffic Safety Administration (NHTSA)
that the belt buckle in a 1975 Chevrolet Monza had unlatched in a fatal
rollover crash, the agency tested the buckles in three 1975 Monzas.
It found that a blow on the back could indeed make them unlatch.
The agency then ran 225 tests on the buckles of 32 cars manufactured between
1971 and 1978, striking the buckles on the back with a rubber-tipped plunger:
they unlatched 50 times, including 11 times when the belts were drawn taut
at 30 pounds of tension.
NHTSA’s conclusion was striking
in its denial of the facts: it criticized both the results and the testing
techniques as not “realistic” enough and said a better testing method
needed to be developed.
The agency also reviewed
“real world” crash data and said it found no complaints and no clear evidence
that buckles had become unlatched in crashes. It suspended further
experimentation.
1992: CBS Hits a Nerve
CBS News began investigating
reports of failed safety belt buckles in the summer of 1992 for a “Street
Stories” report on its 48 Hours program. When a reporter contacted
the American Coalition for Traffic Safety (ACTS), an auto industry lobbying
group, for an interview on the issue, the president of ACTS immediately
alerted Detroit automakers. Detroit hauled out the 1978-79
findings and drew its biggest guns.
A “Response Team” was formed
under the direction of ACTS and a “war room” was staffed. The short
term objective, according to an internal Ford Memo: “To keep off
the air or delay the program.”
The day CBS interviewed a
NHTSA administrator, Ford's Washington, D.C., public affairs office monitored
the interview and sent headquarters a blow-by-blow description of it, including
off-camera discussion.
Letters were fired off to
CBS by ACTS and top auto executives warning of an advertising blitz against
the network's report. They mailed similar letters to some 15 key
news executives across the country and followed up with telephone calls
and requests for editorial board meetings.
NHTSA took the unusual step
of repeating to CBS at length and in writing its case that the belt buckles
were safe, based on its 1978-79 findings. NHTSA's letter was also
sent to other media.
A news conference was held
in D.C. to counter the charges, again under ACTS auspices, the day after
CBS broadcast its report.
Full page ads highly critical of
CBS were prepared overnight after the report aired and were distributed
the next day to national newspapers.
1992: NHTSA Ignores
Evidence #2
The day after the CBS report
aired, a petition was filed asking NHTSA to do four things:
1. Open a new defect
investigation leading to the recall and correction of defective belt buckles.
2. Warn motorists
about the "nature and magnitude" of the defect and the hazard it posed.
3. Advise police,
researchers and others reporting crash-scene information "that the presence
of an unlatched belt following a car crash does not mean per se that the
belt was not being worn prior to the crash."
4. Strengthening the
governing safety standard, FMVSS 209, whose relevant part now requires
only that the "buckle release mechanism . . . be designed to minimize the
possibility of accidental release." (Emphasis added. Europe's
standard forbids any accidental unlatching.)
NHTSA requested information
from Ford and General Motors including: the number of vehicles sold
by type of safety buckle; all test results involving safety belt buckles;
a description of and the reason for any modifications in buckle design
related to the defect, and any complaints or other information on file
about "real world" belt buckle failures.
Ford's responses were typical
of the industry. It provided a full report on vehicles sold and the
types safety belt buckle with which they were equipped, but:
It could find no relevant
crash test information, despite internal records showing repeated failures
of belt buckles in tests at least as early as "parlor trick" tests in 1971,
and a test in 1974 that concluded: "After the seat belt buckle assemblies
were impacted a few times, the release spring would weaken, resulting in
a lower impact level required for release." (GM also failed to report
dozens of belt unlatchings in crash tests.)
It insisted it had made no
design changes related to the defect, even though Ford began switching
from "side release" (push buttons on the buckle's face) to "end release"
(push buttons on the buckle's top edge) designs in the mid-1980s.
By 1992, 40 percent of Ford's new cars were equipped with "end release"
buckles. It contended the change was for "styling preference" reasons
alone. (End-release buckles had already been in wide use in Europe.
NHTSA and automakers insist they provide no additional safety.)
It knew of only one buckle
failure "allegation," in 1978, but said that buckle had been installed
backwards, with its release button against the occupant's body, and that
something had struck the back (exposed) face of the buckle to cause it
to unlatch. However, the petition asking for the 1992 investigation
identified 18 lawsuits alleging that belt buckles had failed in crashes,
eight of them against Ford, six against General Motors. Also, Ford's
own "Owner Relations/Allegations" database shows a history of customer
complaints about buckle failures.
NHTSA ran impact tests on
buckles from GM, Ford and Nissan. Buckles unlatched at impact speeds
as low as 7.7 miles per hour. In other tests, a human volunteer threw
his body hip-first against the buckles 20 times. The buckles unlatched
45 percent of the time.
The agency concluded, however,
that the speed at which the body had to impact a buckle to unlatch it was
higher than could be achieved in a crash because "properly worn" belts
allow only an inch or two of clearance and belt tensions are too high during
the crash to permit unlatching. This ignored the reality that belts
are almost always worn more loosely than that, and additional slack results
from occupants being seated slightly out of position or other factors -
for example, the rapid shifts in position that result in multiple-impact
crashes and rollovers.
NHTSA again closed its investigation
without taking action.
What NHTSA Didn't ‘See'
After examining the record
of the 1992 investigation, Syson-Hille and Associates, a private engineering
firm, informed NHTSA that:
Seat belt buckles have unlatched
in more than a hundred crash tests using dummies, and NHTSA's own data
show that these buckle failures occurred at impact speeds similar to those
of tests on the buckles themselves when they failed.
Although NHTSA said it had
reviewed thousands of crash tests looking for failed buckles, the agency
has conducted few tests of the types of crashes likely to result in inertial
unlatching - multiple impacts (NHTSA conducts no such tests), and side-impact
and rollover crashes (in which test dummies are typically unrestrained.)
Both Ford and General Motors
failed to give NHTSA their own test data that showed dozens of buckle failures.
When NHTSA cited its 1978
laboratory testing results, it failed to mention that the tests were run
because the agency's own crash investigators had found that a safety belt
buckle had unlatched in a real world crash.
The agency said it had done
detailed analysis on selected real-world crash reports that indicatedbuckle
failure, but inertial release seldom leaves any evidence, and crash reports
seldom note the likelihood of belt buckle failure because investigators
don't look for it.
Some Hard Facts
Is the problem real or is
it, as automakers would have consumers believe, just a "parlor trick"?
The evidence is overwhelming that there is, indeed, a problem, and that
both automakers and NHTSA know it.
Lab Tests: Mathematical
analysis and strobe-light photography of laboratory tests by Blick Engineering
and Emtec Corporation concluded that under certain conditions, buckles
can unlatch in crashes. The conditions are not unusual in real world
crashes, especially rollovers and those involving multiple impacts.
Unlatching can occur if:
At least two inches of slack
exists between the belt buckle and the occupant's body. (Five inches
of slack and more is not uncommon.) Belt tension is less than 10 pounds.
The belt buckle is moving at about the same speed as the vehicle. The occupant's
body strikes the buckle at more than 9 miles per hour.
In the tests, buckles swinging
from a pendulum against a human hip unlatched 40-50 times at impact speeds
between 9 and 15 miles per hour. The engineers noted: "(A)ll subjects
stated that the perceived impact force was very low and did not leave any
bruises on the impact area."
Air Safety: The Federal
Aviation Administration (FAA) reported in 1996 that during an airworthiness
inspection it discovered that in seat belt assemblies, "the buckle may
inadvertently open on impact, thereby negating (their) safety value…."
The buckles, it said, were "not unlike the type…installed in many automobiles,
including those manufactured by General Motors and Ford Motor Company."
The FAA field investigator
recommended testing all such buckles by pulling the belts taut and striking
the face of the buckle, and replacing them "prior to further flight if
this test causes buckle disengagement." The FAA said it had looked
in vain for "any automotive service bulletin, letter, or recall notice."
Truck Recalls: NHTSA
itself, in a 1996 list of safety recalls, included Chevrolet and GMC pickup
trucks, listing as the safety defect acceleration forces that had caused
seat buckles to unlatch. The recall, presumably, was to reduce the
forces, not improve the buckles. Patents: More than 300 U.S. patents
and 50 foreign patents for seat belt buckles contain features designed
to resist inertial unlatching. At least 50 patents include specific language
that the designer's intent is to reduce the likelihood that inertial forces
will cause buckles to unlatch in crashes. In 1992, Safetyforum.com
informed NHTSA of language in a General Motors patent that calls inertial
release "a problem of sufficient magnitude that [industry] would invent
and patent these intended solutions."
Europe's Standard:
Europe similarly recognizes the problem as real. Its safety standard states
that a safety belt buckle "must withstand 5,000 opening and closing cycles….
Its self-release must be impossible, both with the belt slack and under
the influence of inertia. The buckle, even when not under tension,
shall remain closed whatever the position of the vehicle." The U.S.
has no such standard.
False Assumptions:
Police and other investigators routinely assume that if a belt buckle is
disengaged after a crash, the occupant wasn't wearing the belt. Even
if investigators do search meticulously for direct evidence of inertial
unlatching, they are unlikely to find it, given that inertial release can
occur at impact forces as low as 30 pounds, leaving no trace evidence on
either the hardware or the person belted. Automakers' insistence
notwithstanding, any conclusion from the lack of such evidence that the
safety belt in question was not in use is unwarranted.
Belt Usage Data: Analysis
of reported safety belt usage in real world crashes reveals a surprising
discrepancy: persons involved in non-rollover crashes are much more
likely to be reported wearing safety belts than those in rollover crashes
(those more likely to result in inertial unlatching). Almost three-fourths
of all car, van and sports utility vehicle occupants involved in non-rollover
crashes are reported to have been wearing safety belts, but only a little
more than half of those in rollovers.
The data prompted the Syson-Hille
and Associates in 1999 to ask that NHTSA reopen its belt buckle investigation
yet again. "These data suggest that either the folks involved in
rollovers are incredibly careless, or, more likely, that as many as 30
percent of the seat belts originally worn are not remaining fastened in
serious rollover accidents," Stephen R. Syson wrote the agency.
"My case by case analysis
of more than 100 rollover accidents has resulted in the conclusion that
many serious and fatally injured vehicle occupants were reported as being
unbelted when, in fact, physical, testimonial and medical evidence proved
conclusively that they were belted…. The most likely cause of buckle
opening remains inertial separation."
(03/01/02)