In a spectacular event, a TV production crew have deliberately crashed an empty Boeing 727 into the desert in a remote location in Baja California, Mexico for an upcoming documentary.  With cameras inside and out and sensors wired to record measurements – it will certainly be must-watch TV – but what will we learn? [caption id="attachment_6712" align="alignnone" width="403" caption="The remains of the 727 after the crash (Channel 4)."][/caption] The crash was arranged as part of a demonstration for a forthcoming TV documentary for Channel 4, Discovery and Germany’s Pro Sieben channels by programme makers Dragonfly Productions, with the aim of recreating a ‘serious, but survivable’ airliner crash with a real aircraft . The aircraft used a pilot who, C4 who in the orginal press release say ‘ejected’ (most likely bailed-out) and the airliner was flown into the desert remotely from a chase aircraft. Footage of the incident shows the aircraft slowly heading to the ground, in a wheels down configuration until it hits and the nose section detaches. (Update - C4 now say "The crew parachuted, there was no ejection"). The TV production company says the airliner was packed with scientific instruments, including crash test dummies and  dozens of cameras to record the event from inside and out. Says Channel 4 senior commissioning editor David Glover: "We hope that this documentary will provide valuable new scientific results as well as giving passengers vital information about how they can improve their own chances of surviving the extremely unlikely, but frightening, prospect of being in a serious plane crash”. This experiment is not new. In 1984 NASA and the FAA deliberately crashed a Boeing 707 into the desert in the US at high speed (footage of which TV and film makers often reuse) to investigate a fire-suppressing fuel additive. So an updated version of this, in high definition with mini cameras can only be a good thing right? Possibly – or possibly not. Let’s take a look at the specifics.  

Age of aircraft

[caption id="attachment_6713" align="alignnone" width="330" caption="Rear airstairs on the 727 (NASA)."][/caption] First the age of the aircraft – the Boeing 727 first flew in early 1963 – nearly half- a century ago. This, although it is an aircraft with a metallic fuselage and wings  is not wholly representative of the majority of airliners flying today. The reason why the programme makers have acquired the 727 is obvious – it would be (relatively) cheap to acquire and destroy, with the last examples either flying cargo in developing nations or on the scrapheap. Secondly, the 727 was also most likely selected as it has rear-airstairs so the crew could escape and parachute out after they switched control to the chase plane.  

Tri-jet layout

The 727 has three engines clustered around the tail. This is now a rare layout for both Western and Russian airliners  – most of which now have underslung podded engines. Those that do have the engines at the rear (Like CRJs and Embraer 145s) are only twin-engined aircraft. So crashing this design may produce unrepresentative results with regard to passenger safety and where might be the safest place to sit in an aircraft. Having a large, heavy jet engine over the tail section of the fuselage differs from the majority of airliners in service today. In any case, in modern pod under wing type airliners the engines are designed to safely break away from the wing on landing – keeping them (and fire) away from the fuselage.  

Fuel state?

[caption id="attachment_6716" align="alignnone" width="333" caption="NASA Boeing 707 crash test in 1984. (NASA)"][/caption] The crash video and 727 wreckage image above shows no fire, the programme makers have also not revealed yet the fuel state of the 727 on its crash landing - which obviously makes a signifcant difference to the chances (or not) of a post-fire crash. Was the aircraft fully fuelled or not? Most aircraft on landing will be flying with significantly less fuel in their tanks than take-off and indeed it is standard practice to ditch excess fuel to reduce weight before landing if there is an emergency immediately after take-off that needs a return to the airport.   

Improved cabin safety standards

[caption id="attachment_6714" align="alignnone" width="333" caption="NASA also used a cabin full of dummies in its 1984 test. (NASA)"][/caption] Passenger seating – Passenger seats, too, are now required to pass stricter standards than ever before. Since 2005 seats capable of withstanding 16G forces have been mandated – and the previous standards were updated in 1988 to allow for dynamic landings and the motion of limbs and the head. Even if newer seats are used in the experiment, it is unclear whether the floor seat track and structure would be representative of a modern airliner where this is designed in from the beginning.  In addition overhead baggage storage bins have also been redesigned from earlier times so they are less likely to detach from the cabin ceiling and injure (or kill) passengers in a crash landing. However one caveat here is that passengers are now bringing ever heavier and heavier bags as carry-on luggage and thus pushing overhead bin structural strength to their limits - a factor which is concerning manufacturers.   

What are the parameters?

[caption id="attachment_6717" align="alignnone" width="333" caption="Even NASA had to tweak the conditions slightly to make sure the fuel tanks ruptured. (NASA)."][/caption] Some of the test parameters are still unknown. The video shows a shallow impact trajectory, wings level with the wheels down, which might be more indicative of very heavy landing without flaring. Remember also that while this is crashing on flat ground, it is not a prepared concrete runway. In the cabin, are the crash test dummy passengers adopting the brace position or not? In short, what are the scientific test conditions? It is worth remembering that even the famous NASA 707 test was skewed slightly in that obstacles were put in the crash area designed to rip open the fuel tanks, since that was what NASA/FAA was particularly interested in testing (and why the film footage of the fireball is so spectacular). Finally (and this is yet to be confirmed by the progamme makers) if this was a truly scientific test then we would expect to see representatives from the aviation regulators, such as the FAA, EASA or even NASA to provide specialist advice, input and assistance in such a complex and expensive demonstration.  

Summary

[caption id="attachment_6715" align="alignnone" width="317" caption="Tests revealed passengers should remain in their seats during turbulence."][/caption] So is this TV event science or stunt? Any attempt to add to the knowledge and science of aviation safety should be welcomed – especially if it highlights ways in which passengers could increase their chances of survival. How many of us these days really listen to the safety briefing and note the emergency exits or how to open the doors? In addition when the programme airs they will be no doubt more information about the experimental conditions and parameters - which may answer some of the above questions. But the choice of a 50-year old design, however logical, raises questions about the validity of some of the findings. A vastly more useful test to the aviation community (and hideously more expensive) might be to take a composite aircraft, like the Boeing 787 Dreamliner now entering service, and see how that performs in a crash. Even an aircraft from the 1990s, such as an Airbus A320 would provide more of a representative aircraft in widespread service to test. In car terms destroying a 727 is like crashing a 1960s Jaguar E-type and attempting to extrapolate the results for road safety on today’s roads. Though E-types are still driven and its is still a car, the usefulness is likely to be more limited. [caption id="attachment_6719" align="alignnone" width="333" caption="In 2010, an Airbus A380 safely landed despite suffering major damage to its wing from an uncontained engine failure. (via David Evans)."][/caption] You might say that with a metallic tube, wings and jet engines aircraft design has not changed that much since the 1960s so the test is still valid. However, consider the Airbus A380 – in November 2010 a Qantas A380 survived a severe uncontained engine failure that probably would have downed an earlier generation aircraft. That is not to say that the aviation industry can ever be complacent in its approach to air safety. New technologies, new materials used in today's airliners present new challenges - which are currently under discussion, though specialist forums like the Royal Aeronautical Society's Flight Operations Group.  Human factors too, such as command skills and pilot training also present a key challenge - again the RAeS is playing its role in addressing these along with pilots, engineers, manufacturers, regulators, airlines and other stakeholders.   In short - aviation safety and aircraft design has evolved massively in the past 50 years since the 727 first flew and is continuing to evolve to meet the challenges of tomorrow. Enjoy the high-definition slo-mo crash footage – but be ready to take any ‘conclusive’ findings with a pinch of salt!

Tim Robinson
1 May 2012