The US Federal Aviation Administration has alerted the general aviation community that a large number Honeywell Bendix/King navigation systems are unfit for arrival, departure or approach operations due to an error made by data provider, Jeppesen.

According to an "urgent navigation database safety bulletin" issued by Honeywell on 11 January, databases for units including the Bendix/King KLN900 for business aircraft are unusable if loaded with the 14 January database, and must be updated with a correct version before resuming the operations.

Jeppesen says that due to an "oversight" on its part, the database did not include a dynamic magnetic variation adjustment for terminal and en route waypoints, an error that could cause the system to calculate erroneous courses and bearings.

The dynamic magnetic variation, Jeppesen says, is calculated from a table that is supposed to be updated every five years to track the slow movement of the Earth's magnetic field. However, that table was not loaded when the company created the latest version, causing the magnetic variation to have a value of zero in the navigation database sent to Honeywell for a wide variety of units it sells.

Jeppesen says it discovered the error on 29 December as the result of post-processing verification steps - at about the same time some of its customers found the error. The FAA considered issuing an airworthiness directive for the error, but ultimately decided to issue the safety bulletin instead, it adds.

"We're doing a root cause analysis to understand why it happened," says Jeppesen, adding: "As a result of that, I think there will be some learning so that in five years it doesn't happen again."

Source: Flight International