Allow me to provide our point of view for readers of The Times regarding "A Skeptic Under Pressure" (Sept. 27), which stated "there is no manual override system" for the Airbus A380 cabin pressurization system. The new A380 aircraft does feature a highly advanced manual override system -- one that is different from and represents an improvement over previous designs.
Traditional aircraft typically have two pressurization valves with automated controls to achieve correct cabin pressure. In an emergency, a pilot can turn off the automated system and manually switch on another motor to directly regulate cabin pressure. However, this system leaves some room for error. If a pilot switches on the manual override system by mistake, it could produce a dangerously low amount of oxygen in the passenger cabin.
By comparison, the A380 has four pressurization valves. Our override system allows the pilot to control the valves through a separate computer system in case the automated pressurization system fails. This backup system prevents the accidental creation of a dangerously low oxygen level because it will allow a pilot to select only a safe aircraft cabin pressure.
The differences between older override systems and the A380 are akin to those between a manual typewriter and a computer-based word processor. Both systems effectively transfer a user's desired keystrokes to a printed page, but the computer-based method includes safeguards that reduce chances of a spelling error.