Military Vehicles, March 1997,: The M-151 Roll Over Debate

The M-151 Roll Over Debate

Chuck Chriss (Chuck_Chriss@qx.com)
13 Mar 97 14:35:31

Dear Gary:

I am very glad to read your personal experiences with the M151 since I always
prefer facts and personal experiences to opinions.

There is no question that the M151 and M151A1 had the tendencies you describe
and that the M151A2 was an attempt to fix it which did make the situation
better. I drove an A2 almost every day for several years. I also visited
military posts (Army) all over the northeast, south, and southwest US and met
with maintenance personnel to discuss the M151 (this was unofficial -- just my
interest). I am also very experienced as a statistician and so tend to be
slow to accept figures which are thrown about without foundation (this is not
about you -- I think you are right on).

First of all, statistics are relative. If there were 200 fatalities in a
certain period of time with the M151, how does that compare to other vehicles
driven an equivalent number of miles during a similar time period? For the
M38, would the equivalent number be zero? Very doubtful. So you have to
look at a control period and try to find out if the equivalent number was 195,
100, or 300. Then, if you were very careful in developing the numbers, you
can start to talk about an "excess" due to the M151.

Now, there have been "statistics" released by DoD on M151 rollovers and they do
show an increase in this type of accident vs previous quarter ton vehicles but,
as I recall, not a very large excess. There was also no backup data showing
how these numbers had been developed and how controlled the study was. But
for the sake of arguement, say there was an increase in rollover accidents with
the M151 series. However, this is like saying that there has been an increase
in people electrocuted by opening up a computer power supply. 20 years ago
very few people had access to computer power supplies while today millions
do. So what other factors may account for the M151 statistics?

Turns out there are several:

1. Drivers entering the service are less experienced. Young recruits in the
mid-1970s and onward primarily learned to drive automatic transmission vehicles
on smooth roads in suburbs and cities. Prior generations tended to be farm
boys who grow up with tractors, pickups, etc. with manual gears. Or from
factory towns where modified high-performance cars were very common and skilled
driving was a mark of distinctrion. Civilian drivers generally drive at higher
speeds than earlier generations in cars and on roads that support that type of
driving. This makes a difference in what they expect from a vehicle and how
they react. This was not true for everyone, of course, but the balance has
shifted over the years.

2. Highway snow removal has become much more efficient in the US leading to
fewer drivers experienced with skids, recovery of control, and slippery driving
conditions in general. Highways in general have been improved with fewer steep
hills, tight curves, etc.

3. Various problems with the recruits' motivation, attitude, respect for
authority, drug/alcohol use and other psychological factors leading to MVAs.

4. The military now consists of volunteers, includes women, and other factors
of change which may have a bearing on driving habits and therefore MVAs.

5. Finally, the type of equipment mounted on the vehicles at some point began
to exceed the design parameters. As you mention, radios make the units top
heavy. So does a 105RR, TOW, Xenon searchlight, too many ammo cases or
people etc. This was fed into the HMMWV design spec and why they went to a
5/4 load rating.

My unscientific survey of Motor Sargeants led me to believe there was no
problem with the vehicle. Bottom line (in my opinion) is that the M151 was a
little more rollover prone because of the IS design; this defect was greatly
improved with the A2. The actual accidents (body count) had more to do with
other factors than the M151 itself. Therefore, this does not support
destruction of the vehicles or banning them from collectors.

Thanks for your input,
chuck

====================================================
About M-151 Roll overs: I haven't felt like diving into the fray over this
vehicle before now but it seems like there are lots of opinions out there
so I thought I would serve up some facts. The following is NOT a
collection of my opinions except where noted. I will simply relate what
happened during my 20 years in the Airforce, pertaining to this vehicle.
I had lots of time with the M-38 jeep with radios in it. I never had
any trouble with that vehicle. Later the AF bought M-151s and with HF,
VHF, UHF and FM radios it became the MRC-107 Radio vehicle. We thought it
handled and rode well but the rear end made so much noise the enemy could
hear you coming 5 minutes in advance. As time passed rumors arose about
roll over fatalities around the world. This phenomena had not arisen with
the M-38. After more time, enough of these "alleged" roll overs became so
frequent that, by now, we knew some of the people that suddenly became
dead. Installation of a roll bar or roll cage was suggested. The Air
Force replied (You will love this!) that "If roll bars were installed,
drivers would be encouraged to drive recklessly". (Then why do we have
helmet laws and seat belts?)
After the body count reached 200 in the combined services (This was the
published figure.) The Air Force created a world wide training program
including a training film to educate and warn drivers of the roll over
danger inherent in this vehicle. They would not issue a license to drive
one of these to anyone who had not been through the course. My opinion:
This is a lot of effort and money to expend on a vehicle that compares
favorably to others in it's class.
An Air Force memorandum on this vehicle explained that the independent
suspension caused drivers to be lulled into a sense of security because
unlike straight axle vehicles, the impending feel of possible roll over was
lacking and due to the suddeness, control was irretrievable. Further, a
straight axle vehicle tends to "wheelbarrow" out of the roll over, giving a
moment of warning while the independent axled M-151 would "launch" the
vehicle over the CG without any significant warning.
This is the story, from the Air Force as well as I can remember it. In
my whole military career, I never saw the service jump through their own
butts over a piece of equipment as much as they did with this one.
One last fact. My best friend was killed at Fort Bragg when an oncoming
vehicle forced him to take instant and severe evasive action. A passenger
in the jeep was thrown clear and survived. I have no opinion about this
except to note that the radio package makes this vehicle quite top heavy.
Again, my opinion (shared by a lot of others): We entered WW-2 with
an obsolescent main battle tank and a WW-1 designed General Purpose machine
gun. Even a late as the Vietnam era our troops were issued the M-60
machine gun which is demonstrably inferior to the German MG-42 which the
Germans designed in 1942! We couldn't do better with 25 years to do it in?
My opinion: Politics determines what is purchased not function.
As to the M-151 however, I wouldn't drive my loved ones on the highway
with one.
G.R. Downing USAF, Ret.