The Problem
Aging aircraft and systems lose capabilities. Take Autoland for example. Autoland fully automates the landing phase of an aircraft’s flight and requires that the Inertial Reference Systems (IRS) have an accurate magnetic heading output. But all IRS work in true heading and output magnetic heading by looking up the magnetic variation (Magvar) in a table stored in the system’s memory. As time goes by, that table becomes inaccurate because magnetic north moves compared to true north and the Magvar tables aren’t being updated.
This is well understood and predictable. Aircraft manufacturers slowly remove Autoland capabilities at airports which were previously approved for Autoland, as the difference between the real magnetic heading and the one generated by the IRS exceeds limits.
Our partners at Mid-Canada Mod Center had a client with a medium-sized single aisle passenger jet. The client wanted to restore Autoland capability at certain airports and extend the life of the aircraft. Our partners brought us an idea. Could we certify a new IRS in the aircraft and restore the Autoland capability at these airports?
Our Approach
Certifying a new IRS was the easy part. But we had never been involved in an Autoland project before. We had to develop new skills and acquire new knowledge, but that’s what we do.
The Solution
We replaced the IRS and worked with the manufacturer to fully understand the magnetic variation data stored in the IRS. We plotted this data against the predicted magnetic variation at all of the airports with original Autoland capability and created a new Autoland list with new calendar limits.
We flight-tested Autoland at a selection of the airports that the aircraft manufacturer had previously withdrawn Autoland approval from. We created a new Airplane Flight Manual Supplement that restored Autoland at these airports.
The Result
ADS met the challenge. The useable life of this aircraft was extended with the resurrection of the Autoland capabilities.
