The passenger airbag is typically the most powerful airbag in the car - it has to be, because of the space it needs to occupy to provide protection. And while the steering wheel is pretty much mounted in the same place, the dashboard offers up a multitude of ways to mount a passenger airbag. In the history of passenger airbags, they have been mounted everywhere from low on the dash (in front of the passenger's legs) all the way to a full, 90-degree top mount, but the general categories are "mid-mounted" and "top-mounted".
A "mid-mounted" airbag is mounted to directly face the passenger, coming out directly toward them horizontally. This 1999 Chevy Silverado is a textbook example. Some "mid-mounted" airbags are angled slightly upward - like the 1994 Lincoln Town Car, for example - or have a portion of the door facing upward, for example this 1994 Toyota Camry - but if any portion of the airbag door is facing directly toward the passenger, it's mid-mounted. This was a common design on early passenger airbags - from the 1990s - but has fallen out of favor, being used on few new vehicles today.
A "top-mounted" airbag is mounted atop the dash, deploying initially toward the windshield then wrapping back around. This design was pioneered by Honda in 1991 and adopted by most vehicle designs by the early 2000s. The 2003 Honda Pilot is a textbook example of a "top-mounted" airbag. The top-mounted airbag doesn't necessarily have to be at a 90 degree angle (directly atop the dash), but if it's much closer to vertical than horizontal, it's considered top-mounted.
It would, at first glance, seem to be an aesthetic decision: what could be wrong with a passenger airbag directly facing an occupant? After all, the driver airbag is pointed straight at you.
A "mid-mounted" airbag is mounted to directly face the passenger, coming out directly toward them horizontally. This 1999 Chevy Silverado is a textbook example. Some "mid-mounted" airbags are angled slightly upward - like the 1994 Lincoln Town Car, for example - or have a portion of the door facing upward, for example this 1994 Toyota Camry - but if any portion of the airbag door is facing directly toward the passenger, it's mid-mounted. This was a common design on early passenger airbags - from the 1990s - but has fallen out of favor, being used on few new vehicles today.
A "top-mounted" airbag is mounted atop the dash, deploying initially toward the windshield then wrapping back around. This design was pioneered by Honda in 1991 and adopted by most vehicle designs by the early 2000s. The 2003 Honda Pilot is a textbook example of a "top-mounted" airbag. The top-mounted airbag doesn't necessarily have to be at a 90 degree angle (directly atop the dash), but if it's much closer to vertical than horizontal, it's considered top-mounted.
It would, at first glance, seem to be an aesthetic decision: what could be wrong with a passenger airbag directly facing an occupant? After all, the driver airbag is pointed straight at you.
Driver airbags are much less powerful than passenger airbags by their very nature; they typically have to inflate only about half as large as passenger airbags in the same time. In addition, there is a much wider range of possible occupant sizes in the passenger seat - potentially including small children.
With a mid-mounted passenger airbag, the initial force is directed straight out toward the occupant - a powerful blast that can exceed 2,000 pounds of force, often aimed directly at the height of a child’s head. Occupants in the airbag’s deployment path - which can be 2-3 feet deep in older cars - are subjected to the full force of the airbag. Of course, newer “depowered” and “advanced” airbags are less dangerous, and things like tethers (as commonly used on driver airbags) can make them even less dangerous, but by their very nature mid mounted passenger airbags are potentially more dangerous than a top mounted one.
What is not so obvious is the fact that mid mounted airbags can hamper or even prevent access to a glove box following a crash. While this is obviously a much less severe issue, mid mounted airbags often have airbag doors that open inches from the glove box, and there are even designs where the airbag door and glove box door share a seam. On some cars, that’s a 2,000 pound force coming out right next to the glove box latch, not to mention you have to deal with the hot deflated airbag - that is, if your glove box still opens. What if your cell phone were in the glove box? Yikes!
Top mounted airbags deploy initially upward, along the windshield, before curling back toward the occupant. When a pre 1998 (first generation, full power) airbag breaks the windshield, that’s actually a good thing, that’s force that’s not coming straight back at the occupant. Many newer top mounted passenger airbags deploy in such a way as to not break the windshield. This is much less dangerous to vulnerable occupants. And, because the airbag door is typically a significant distance from the glove box door, it’s easier to put the deflated airbag atop the dash and access the glove compartment.
This MotorWeek clip from 1989 shows an early mid-mounted passenger airbag design (around 3:11) and even with the seat properly positioned, the airbag clearly jostles the adult-sized dummy significantly. If you look at a list of people killed by passenger airbags, the majority were killed by - you guessed it - pre-1998 mid-mounted airbags.
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