Hello everyone,
After returning to flight simulation following a break of more than 40 years, I've been rediscovering the pleasures of traditional radio navigation in MSFS 2024 and X-Plane 12 - after the A2-FS2 Flight Simulator II for the Apple II+ in the 1980s, a remote predecessor of the MSFS2024.
That led me to another old interest: programming the Texas Instruments TI-59 calculator from the late 1970s.
Using Pascal Obry's TI-5x emulator for Android, I've developed three programs that calculate an aircraft's geographical position using traditional radio-navigation instruments, without GPS:
- VOR/DME: Position from a VOR radial and DME distance, including optional slant-range correction.
- VOR/VOR, VOR/NDB and NDB/NDB: Position from the intersection of two radio bearings, including ADF handling and a check of the intersection geometry.
- DME/DME: Position from distances to two DME stations, including both possible intersection points.
All three use the original TI-59 instruction set. Two even fit within the memory limitations of the original calculator; the third requires the emulator's expanded memory.
The programs run independently of MSFS, so they can be used with MSFS 2020/2024, X-Plane or other flight simulators. They are intended for enthusiasts who enjoy navigating with VORs, NDBs and DMEs rather than simply following a GPS route.
I've made the programs, source code, keyboard overlays, documentation and test data freely available:
https://guest.engelschall.com/~sb/download/#Aviation
Source code on GitHub:
I'd be interested to hear whether anyone else enjoys combining modern flight simulators with historical navigation techniques — or perhaps even remembers using programmable calculators for navigation!
Best regards,
Steffen