Cambridge Flight Recorders


Cambridge GPS Error & Repair

The Cambridge line of flight recorders by Cambridge Aero Instruments have reported a rash of Cambridge Model 10/20/25 and 302/302A faults in which the units lose track of the date and do not record a flight log, or record a flight log with an incorrect date. The problem is related to the internal Garmin GPS engine’s UTC date. This is a new issue, but there have already been many reported instances – especially from areas in which there are soaring flights this time of year. It is very likely that many 302 and GPS-NAV owners that have their gliders put away for the winter will, unfortunately, have the same issue during their first flight in the spring.

To learn more, and repair your unit, read this important information from Paul Remde of Cumulus Soaring Inc.


Cambridge 302

The Cambridge flight recorders by Cambridge Aero Instruments are very popular with soaring pilots, especially the model 302 which combines;

  • A very accurate GPS with external antenna
  • An FAI certified flight recorder
  • An audio variometer
  • A flight computer (speed to fly, etc)
  • Can supply/read data to/from a PDA/PNA
  • Can supply 5V power to a PDA/PNA
  • A G-meter (non-logging)
  • Temperature probes (internal/external)
  • A myriad of informational tones
  • Has an airbrake warning system (external connections and switches are required)
  • Can connect to a 303 display
  • Etc, etc, etc

Below is some reference information which may be useful to users of these flight recorders.

Note - The Cambridge 302A is very similar in features and functions to the 302 without the LCD display or the audio vario. It is an approved flight recorder and it will supply power/data to/from many PDAs or PNAs.


Cambridge 302 Tones Explained & Decoded
When I purchased the Cambridge 302 I was somewhat bewildered by the various tones that the 302 can make during flight.

You can easily "keep your head out of the cockpit" by being able to listen for lift, sink, speed to fly (speed up or slow down), gear/airbrake warnings, slow speed alarm and even SUA alarms (initiated externally e.g. from PDA software). After flying with the 302 for a while the various tones start to make some more sense.

Unfortunately, the 302's manual is not very good (IMHO) at describing these tones and their meaning and usage. The manual has the information scattered in several sections and with less than clear explanations (again, IMHO). To help make this information clearer and simpler, I wrote a short one-page synopsis of the various 302 tones.

To download my 302 tone synopsis, please click here.

Please let me know if I messed up or forgot something. Thanks.


Manuals and Software
  • Manuals - Cambridge 300 series user manuals can be found here.Cambridge 302 dataport reference manual can be found here.
  • Software - There are several pieces of software available from Cambridge that are useful, in particular the 300 series utility and the Cambridge Aero Explorer. Unfortunately, some software seems to be missing from the Cambridge 300 series web site (broken links). You can download the files from Cumulus-Soaring or from my backup collection here. NOTE: Some software doesn't work on newer Windows systems.

Cumulus-Soaring Information
Paul Remde's Cumulus-Soaring store's web site has some very good information on the Cambridge line of equipment. See this web site.

Paul has also produced a very nice training video on the Cambridge 300 series equipment. See this web site.

Simulators and Cambridge software is available here.


Cambridge 302 Logging Errors
There is a fairly well known "bug" with a few Cambridge 302 flight computers (and the 302A I assume) in which one of a number of issues can arise;
  • Will not record flights
  • Cannot download log files
  • "Could not get FAT" error message when downloading log files
  • Flight log review, or scoring, reports a security error
Per Cambridge, the 302 is designed to continue to store your flight's log entries even when reaching the end of memory by automatically "wrapping around" the end of memory and then start overwriting the oldest log file(s) but the latest log file is split into two pieces. It seems that the overwriting occurs correctly and the log file is written to memory.

Conjecture: Later when you go to download your "split" log file, the two log file pieces may not be correctly joined back together into a single file and the above issues can surface. Maybe. Who really knows? However, these issues have been reported often enough that this issue has been given wide credence. I believe that Cambridge has commented that this may have been caused by a batch of sub-standard components.

The commonly held solution to this problem is to clear the 302's memory. Unfortunately, doing so will erase all your log files in the 302 including the one you desperately want! Before resorting to this quite drastic cure, you should make every attempt to download log files several times, and in as many different ways as you know how (via Cambridge software, SeeYou (desktop), Naviter ConnectMe, GlideNav, etc), talk to friends, find a contest score, etc.

If you are really desperate, you could ask Paul Remde of Cumulus-Soaring if he could work with you to retrieve your log files. I'd suggest sending him the unit for recertification which should be done every 5 years in any case (changed from every 2 years in 2013). Ask Paul to help on the log file retrieve and/or clearing the memory.

Here are some instructions;

  • Via a PC - Paul Remde has a good explanation of this issue and a fix in his November 2007 Newsletter.
  • Oudie Users - You can find how to do it here
  • Other Information - Please see this document for more details from many authors and sources (thanks!) on the various procedures to clear the 302's memory.

Cambrige 302 "Fake" Issues
There are a couple of things that can happen to a Cambridge 302 that seem like the unit has failed but isn't really a major problem. I call these "fake" issues.
  1. Slow Startup - Over the winter I took my instrument panel home to putter. About 3 months later I turned on the unit and found the the 302 would cycle its start up tones over and over again for 5-10 minutes before getting to the "set pressure" screen. I thought the unit was broken. I ultimately found that it had to do with the GPS. I had earlier cleared the memory on the 302 which, I assume, also cleared the last know GPS location. So the 302 had to start from scratch to find satellites ... plus I was indoors. Once outside and a GPS fix was made, startup then happened normally. Of course it could really be issue #2 below.
  2. Stuck on Startup - The symptom is that the 302 gets stuck at one of the startup screens. I've never seen this myself but I think that it is the "version number" screen. Anyway, this is often caused by the Outside Air Temperature (OAT) probe being disconnected or not seated properly. Remove and reseat the probe connector usually fixes this problem. Of course it could really be issue #1 above.

Good luck!

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