Why hasn't multi input INS and GPS (inertial navigation) not reached GA

There seem to be a lot available for UAVs, for example, INS-U, or Honeywell Compact Inertial Navigation System

The only certified ones I found from a cursory search are targeted at commercial aviation, for example, Honeywell LASEREF VI

There is good reading here and here. Here you can find the building blocks; they are not cheap (a few k for MEMS devices with a drift of a fraction of a degree per hour, and FOG devices which cost a lot more).

Probably the basic problem is that GPS does work most of the time, and works ~100% of the time in the country which “owns the GA universe” so the market for a GA inertial-nav product would be small. We saw this when GPS arrived all those years ago; the bottom immediately fell out of the navigation business. It is in flight training where they are desperately trying to hang onto the good old days but nobody uses anything other than GPS today.

Until you fly in the parts of the world where GPS gets jammed, but that still translates to a very small market. Especially as GA barely exists in those parts in the first place.

If a MEMS based (let’s forget FOG based – too expensive and not necessary as MEMS stuff has come a long way in the last 10 years) box costs say 5k then a GA nav product would have to sell for about 50k, working on the markups usually involved. At that price it won’t sell, except maybe into the bizjet world.

Certification is not expensive if you have a system in place for doing it (as all the major players have) but they are not going to do such a product, so anybody else would have to work out how to do it.

Also certified nav boxes have no position input (e.g. NMEA) so you would have to build a box which fakes a GPS signal so that could be connected to your certified nav box.

I think a lot could be done with clever antennae – because GPS is available everywhere. It “just” gets jammed or spoofed by a stronger signal. Start e.g. here.

RobertL18C wrote:

Apparently battle drones have relatively cheap multi source nav: GPS (with anti jamming filtres), INS, visual stored ground mapping.

Why hasn’t multi input INS and GPS not reached GA?

Fully agree with you, this would be really cool and adding another level of safety!

I haven’t heard anything regarding INS, but rumour is that DME-DME RNAV input is expected to be available by 2027 as an option to the GTN Xi series and probably the G1000 NXi.

Yes – that came up here. In the DME-dense parts of the world that will probably remove most of what market there might have been for inertial products.

More RNAV discussion is here.

NCYankee wrote:

rumour is that DME-DME RNAV input is expected to be available by 2027

Definitely want to ask Garmin about availability and features at the Aero next month. Although their answer is PROB80 “We cannot disclose anything more than the press release at this point.”

The recent Garmin DME product announcement suggests this development direction but they seem to have announced it considerably ahead of real availability and detailed information about even that first product isn‘t yet available last I checked. I don‘t think they‘re delivering it yet either.

GPS availability in the US isn‘t 100% as you suggest @Peter. Check relatively recent reports of some widespread outages. But I haven’t heard of a huge outcry yet. Maybe there are still enought VOR‘s around that pilots are able to cope.

In the US they do have GPS jamming for testing.

Not sure whether it affects GA in the US badly enough.

RobertL18C wrote:

Apparently battle drones have relatively cheap multi source nav: GPS (with anti jamming filtres), INS, visual stored ground mapping.

It would be nice if GA had access to modern, solid state, light INS?

It’s a sort of a dilemma. It’s a huge industry involved with these stuff, yet nothing trickles down to GA. Obviously a market situation. Those who need it in aviation have had systems since ages ago anyway in the flight management system (FMS or MCDU in Airbus). There are much more to these systems than meets the eye. Among other things it’s a sensor fusion system that picks all available sources for navigation. “Default” mode is INS/GPS, but in practice it could be DME-DME-DME-VOR-whatever is available. It’s all done under the hood.

But sensor fusion requires sensors and connected systems. Sensors cost money, a GPS receiver is free in comparison. A low cost FMS for GA is therefore kind of hard to imagine. At best it would be a GPS coupled with INS, but that doesn’t really work in the long run if GPS is lost. DME/INS would be much better, and an FMS does this (also) by default. Who will certify a GPS/INS only (for aviation navigation purposes)? Is it even possible without DME/VOR?

Perhaps someone will produce a cheap non certified GPS/INS. Essentially a more robust GPS. Would anyone really care? Even for VFR a DME/DME would be 10x more practical. Added to this is the already existing systems of radar and WAM an all that stuff.