Discovery Channel Airs “Plane Crash” Episode

 - October 8, 2012, 1:59 PM

The Discovery Channel’s Curiosity Show ran an episode last week titled “Plane Crash” that gave viewers a look inside one of the most spectacular safety experiments ever conducted into the survivability of aircraft crashes.

A remotely-controlled Boeing 727, turned into a giant flying laboratory, was purposely flown into the ground at a remote Mexican desert test site to study the results on the aircraft and dozens of heavily wired test dummies seated in the cabin. The safety experiment’s goal was, just as in automobile crash testing, to better learn how to make airliners more survivable for passengers and crew during a crash. Sensors and cameras, in addition to the dummies, located throughout the airplane captured the severity of forces unleashed in accidents.

An airliner test like this has been staged only once before when NASA crashed a Boeing 720 in 1984 to gather data on the usability of a new fuel additive. The test was not successful when the aircraft was engulfed in flames half a second after impact. (Fitz Fulton, the pilot of that remote-controlled flight, believes that the test was a success, because it proved that the fuel additive didn’t work.)

The Discovery Channel show highlights four years of planning that asked questions like whether bracing passengers before impact really has any positive effect. Or, contrary to what aircraft manufacturers say, does the seat a passenger chooses make any difference in an accident? Sensors also highlighted which onboard locations experienced the greatest forces during a crash. The rebroadcast schedule for “Plane Crash” has not yet been released.

Comments

Brandon's picture

First I am an engineer at one of the leading aircraft manufacurers in the world and my specialty is seats. Prior to this posistion, my experience has been in testing and certification of aircraft seats.

On the show last night, the "experts" claimed that the data would be useful to the scientific community. My question is, how useful can it be? There were some answered questions that left a dry taste in my mouth after seeing this show. First, the 727 is a 20+ year old aircraft. Although not stated, this aircraft was probably certified to FAR 25.561 as it relates to seats. This is to say that the seats only meet a certian performance critera that is unequal to the modern airliner which is certified to FAR 25.562. FAR 25.561 is a performance critera in which the seats are only required to meet static test condtions (9g capable in the Z direction). FAR 25.562 on the other hand requires seats to be able to meet DYNAMIC crash landing condtions (equivelent to a 16g deceleration relative to the direction of travel of the aircraft and 14g in a downward direction relative to the occupant). Laboratory experience has shown that most 9g seats cannot meet the requirements of 25.562. There is also a matter of occupancy of the seat. In all airliners, there is an analysis based on seat geometry, weight, and configuration called an interface loads analysis. This reports to the OEM (in this case boeing) that seats instaled on the aircraft do not exceed the allowables of the seat track. It also identifies the worst case seat (seat with the highest interface loading) for a given family of seats (front row, constant section, tapered section, track breaks etc) and the critical configuration of the occupants (how many and where they are seated). It seemed to me that these occupants were placed in arbitraty locations within the cabin at the time of the experiement which is not representative of the worst case landing condtions. They explained in the show that some of the seats were ripped out of the track and it was most likely because the seats were not designed to absorb energy and most of it was trasfered to the track and a failure resulted. In other words the seats are too stiff. The ATD's (Anthropomorphic Test Device) were also Hybrid III dummies. The accepted dummy is the hybrid II but the hybrid III (adapted for aviation use) is slowly being introduced. And also further testing that could have been done was to test the HIC (head injury criteria) at a longer pitch ~34"+ for instance in a transistion row from economy to first class. There is much more energy in a head strike at this configuration. In short these are my observations about the show. I realize that this is entertainment but to say this data can be used for real world application is something that I would need to see more data on to make that dertermination.

tom's picture

Brandon,
I appreciate your comments. The 727 is a old airplane but with the exact same fuselage structure as the 737, one of the most commonly delivered transport aircraft today, and with newly expanded production lines. Also if you look at the 25.562 pulses (by the way, you have several errors in your pulse descriptions), they are ideal triangles. The history of developing these pulses is fascinating and I recommend reading about it, but the bottom line is that interiors are not designed or certified using pulses that represent any particular fuselage structure. The pitch and roll of the floor track are also general. So how well do these ideal pulses represent reality? There is value in that. As you work with seat certification, you are probably aware of the constant battles being fought about how to run the tests, and often the engineers are making assumptions about what might happen in a real crash.

Yes the seats were "9G", we would have liked to get some newer and have put straight spines in the HIII's, but it didn't work out. In the end the seats that were in the intact fuselage sections performed well and we collected floor accelerations that can be applied to any seat analysis. The interface load analysis is important for certifying a seat, but any realistic seating positions are of use in seeing how they perform. We did load a few of the seats with three dummies - but we were not able to fully load everything - there are practical limitations after all.

Technical details were not of interest to a general TV audience. But there will be technical papers getting the data out there to the technical community.
I hope you all enjoyed the show.
tom

dmhennen's picture

maybe they try it straight into the ground next time......then everyone will know that was no commercial airliner that landed in Shanksville.

dmhennen's picture

maybe they try it straight into the ground next time......then everyone will know that was no commercial airliner that landed in Shanksville.

Jonathan Abbey's picture

I personally found this show absolutely fascinating and great entertainment which is really what it's all about. I will definitely be watching it again when it's rebroadcast!

Koy Fizer's picture

Just caught a replay on the Science Channel. Checkout this channel if your looking for a rebroadcast

Show comments (6)