Chapter 1: The Collapse of a Star
The first-generation of IRS (Internal Navigation Systems) weighed 105 lbs and were installed in the G-I and G-II business aviation aircraft. In the 1980s and 1990s, Honeywell developed the LASEREF II and III. These units were leaps forward in technology, and remained the mainstay of IN (Inertial Navigation) for 30 years until Honeywell announced a few years ago that some of the components for the LASEREF II and III would no longer be available.
Today there is no LASEREF II or III program. No repairs. No exchanges. No rentals.
The affected aircraft are in every business aviation fleet: Falcons, Challengers, Globals, Citations, and Gulfstreams. Those on MSP Avionics contracts (HAPP) are no longer able to get these units covered. There are usually 2 or 3 of these units on board, and should a failure occur, they must be replaced all at once due to differences in their MagVar (Magnetic Variance) Tables (more on that in chapter 2), which can lead to malfunctions or degradation of heading dependent systems. Honeywell, for their part, has produced a trade-in program that offers new LASEREF IVs at steeply discounted prices. Duncan Aviation has also partnered with Honeywell to replace these units at any of its primary facilities or at any of its satellite shops in its coast-to-coast network. The job takes between 3-5 days depending on the airframe.
Chapter 2: The Unmistakable Magic Of MagVar Tables
Imagine you are going to Gander for fuel (and maybe ice cream). As your Flight Director bars wash out on the intercept to final, you notice that your co-pilot’s compass is 7-degrees off. Due to low ceilings, you planned to shoot the Cat II to Runway 030. As you line everything up, you realize that you can’t get a CAT II approach due to the heading split.
A 2018 ICAO (International Civil Aviation Organization) report stated that much of the intermittency of CAT II and Cat III approaches into Canadian airports was the result of outdated MagVar Tables. I have also heard reports of 10-degree compass splits in the North Atlantic corridors.
What is a MagVar Table? As you know, IRU (Inertial Reference Units) navigate off the relative motion of the earth and have no magnetic input. As radio navigation sources, such as VORs (Very High Frequency Omnidirectional Range), operate via magnetic heading, the IRU calculates a magnetic heading based on a MagVar Table stored in the memory. When these tables are outdated or don’t match the offside IRS, problems can arise. Boeing has also reported heading splits up to 10-degrees related to outdated MagVar Tables in the IRU.
Conclusion: What Do I Need To Do Now?
Give us a call. We can talk about it a bit further and give you some options. Don’t wait until you’re AOG as the lead time on obtaining LASEREF IV units can take as long as 8 weeks. Aircraft brokers have also become quite aware of this issue, so failure to develop a replacement plan will negatively impact the aircraft resale value and prospects.