The inventor who made the black box orange


David Warren, inventor of the flight-recording device popularly known as the black box, died this week

WHEN DAVID Warren, a young scientist at the Aeronautical Research Laboratories in Melbourne, helped investigate the first jetliner crashes in 1953, there was no easy way of telling what happened, apart from a painstaking re-assembly of the wreckage and an over-reliance on often unreliable or – in the event of a crash at night or at sea – unavailable witness statements.

Warren, who died this week, has been lauded for the invention of the black boxes that have been credited in the mythology of popular culture with providing almost overnight solutions to plane crashes.

As Canadian comedian Steven Wright quipped, “why don’t they make the whole plane out of that black box stuff?” If only. The true story is slightly more complicated. Firstly, they’re not black, they’re orange, so as to be easily spotted in a wreck. Secondly, flight data recorders already existed. Charles Lindbergh carried an early model aboard the Spirit of St Louis when he made his record-breaking solo transatlantic flight in 1927. It was encased in plywood and inked data on a paper roll, hardly ideal materials to survive a crash.

Warren’s outstanding triumph was the invention of a crashproof and fireproof container to hold the precious recordings. There were still drawbacks to his design – US authorities dismissed his first samples as not being robust enough and early models failed to survive some high-speed nose-first impacts and prolonged post-crash fires.

Manufacturers produced different iterations of Warren’s prototypes. The British first opted for wire on which flight data was electronically recorded. An early US model scratched tiny graphs on aluminium foil, which needed microscopes to decipher. The French tried light-sensitive paper to hold data, but it vanished if opened outside the darkroom. Despite its early flaws, Warren’s invention helped investigators focus on flaws in both humans and hardware and, by preventing further crashes, has potentially saved thousands of lives.

Warren’s concept faced some of its greatest tests at Colorado Springs in 1991 and Pittsburgh in 1994 when, following almost identical high-speed nose-dives into the ground by Boeing 737 jets, investigators feared recorders might not survive. In Colorado Springs, although the cockpit voice recorder broke apart, the foil tape was recovered from a stream nearby and the data was extractable.

Those accidents highlighted the shortcomings of then US policy on flight data recordings. They captured what the planes did, but not why.

Investigators could tell their altitude, direction and speed, and retrace their final corkscrewing motion to the ground, but were unable to tell what flight controls caused the 737 crashes, and what actions the pilots took to attempt to prevent them. The cockpit voice tapes saved the day.

In the second crash, while the alarmed pilot didn’t say what was wrong, grunts convinced investigators he was pressing with all his might on a jammed rudder pedal. The probe switched from Boeing theories blaming weather or pilot error to extensive research proving 737 rudder design was fatally flawed.

So much for overnight solutions: it took almost a decade to solve the Colorado Springs and Pittsburgh crashes. US authorities then forced parsimonious airlines to invest in more advanced black boxes which revealed not just what the planes did, but what controls the pilots pushed, or pulled.

Instead of just a handful of flight parameters used in the US, European airlines had for years been recording scores, sometimes hundreds of second-by-second details of how their aircraft were flying.

Today engineers in Dublin can tell if a flight to Rome had problems almost within minutes of its wheels touching the ground. Advanced memory cards record both voice and fight data and recordings now last hours, not minutes. The recorders are now almost indestructible, electronic beacons guide searchers to where they lie, and new ones have battery back-ups in case of pre-crash power failures aboard the aircraft.

So it is ironic that the week of Warren’s death could also mark the end of the black box as we know it. One of the world’s worst single air disasters, the loss of Air France Flight 447 off the coast of Brazil in June 2009, is nowhere close to a solution – because neither of the black boxes has been found.

At the Farnborough Air Show this week, two Canadian companies unveiled plans for flight data recorders and voice recorders which constantly transmit data by satellite while an aircraft is flying – meaning engineers on the ground, through monitoring a flight’s data, may be able to forecast and even prevent potential disasters.