If so, there may be liability under legal theories of either negligence or strict liability, suggests public interest law professor John Banzhaf, who, with a degree in electrical engineering from MIT, 2 U.S. patents, and a number of technical papers to his credit, has both technical and legal expertise.
Since a transponder is such an important safety feature, permitting it to be turned off during flight - whether by accident, by trained terrorists, by pilots at gunpoint or voluntarily, etc. - makes little sense unless there is a compelling reason. Experts claims that pilots must be able to turn it off (or at least to “standby”) to avoid cluttering the screens of ground control radar when the aircraft is moving on the ground at an airport, or when it is finally parked, but neither justification applies when the plane is airborne.
So, since it would be both easy and inexpensive to design the transponder system so that it automatically turns on and remains on whenever the plane is in flight (as indicated by an altimeter reading, lowered cabin air pressure, etc.), and such a simple design change would help deal with foreseeable events like hijackings by trained terrorists, malevolent acts by deranged pilots, or even simple pilot error, having a system where a crucial component can easily be turned off when it is most needed sounds like negligent design.
Interestingly, some maintain that the ACARS system cannot easily be shut down. However it, apparently like the transponder, can be rendered inoperative by throwing a switch or circuit breaker. Defenders claim that, in the event of fire or other electrical system problems, the crew must be able to disconnect the power.
But, considering how critical both the ACARS system and the transponder can be, the inclusion within each system of a emergency backup battery would permit the systems to continue functioning at least for a while, even if aircraft power had to be cut in the event of a fire or other emergency.
Would whoever diverted the plane have done so if they knew that the transponder - and even the ACARS system - could not quickly be turned off, thereby giving them the freedom to maneuver without detection during a crucial time period?
If an operating transponder and/or ACARS system had alerted authorities that something was very wrong with the flight, could jets have been scrambled quickly enough to force the runaway flight down, or at least otherwise reduce the apparent loss of life?
To these and other important related scenarios, we will never know the answer, because simple fail-safe principles of design, including providing backup batteries, simply were not followed.
Perhaps, if nothing else, this tragedy will prompt authorities to require simple and inexpensive changes to get rid of the "off" switch on these crucial components while they are airborne, suggests Banzhaf.
JOHN F. BANZHAF III, B.S.E.E., J.D., Sc.D.
Professor of Public Interest Law
George Washington University Law School,
FAMRI Dr. William Cahan Distinguished Professor,
Fellow, World Technology Network,
Founder, Action on Smoking and Health (ASH)
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