How I helped Israeli F15 fighters to continue flying?

F15Few days ago my wife called me “Do you know Yuval Rakhavi?”
“Yes, I do, he I have learned most of what I know in computer programming from him”
Mr. Yuval Rakhavi is one of the founders of BRM and now acts as a director of few Hi-Tech companies in Israel.

This talk about Yuval, reminded me of an interesting case that happened few years ago. At that time I worked as a freelance Linux consultant. While working on a customer’s problem I got a strange phone call “This is lieutenant …” from IAFB-8 Flight control. My immediate thought was that someone is making a joke here. I was at that time at the Israel Air Force technical squadron reserve forces, however I had no connection to Flight Control. At the beginning of my military service I used to be in Flight Control department but in a different air force base. The officer on the other side of the phone continued “Do you remember that on 1989 you built a testing device for Rate Sensor Assembly and Accelerometer Sensor Assembly?” At this point I understood this is not a joke. I did built such a device during my time at the Israel Air Force.

In 1988 while being a software engineer at Israel Air Force special maintenance unit we asked for budget to build automatic test equipment for Accelerometer Sensor Assembly that the unit was maintaining. The officer at Israel Air Force headquarters agreed to give us the budget if we build two such devices and test also Rate Sensor Assemblies. My commander at that time approached me with two US Air Force Technical Orders manuals for the two units (ASA and RSA) Each technical order manual was about 1000 pages. Few minutes later (yes it takes me only few minutes to understand long technical manuals…) I came back to him and said “Yes, we can build it but it might be expensive” His response was “Ok, please design it and let me know what equipment you need” At that time I did not know that the budget was practically unlimited as it was required for the maintenance of F15 fighters that where important part of Israel Air Force.

My task was to write the software for this device, the hardware and purchasing job was given to a young officer that has just joined the unit. I rad again the manuals, the actual testing was easy but it had few hundreds of test that most of them where like “Connect voltage to pin… and measure voltage at pin…”.
This seemed like a boring task to do and I tried to think how to give part of the task to someone else while keeping the interesting part (interfacing the hardware) with me.

I decided to write a simple programming language for such tasks. So I started writing a specification for a new programming language I called GAL (General Application Language). I wrote an interpreter, debugger and interactive system to test it. Including the actual implementation and testing it, it took about a year to write. When the interpreter was ready, I gave a young soldier the actual task of writing the test procedure for both assemblies.

In 1989 we installed a working device in IAFB 8 Flight Control unit and they have used it since then. I was happy to know this was still working at that time.

So returning to the interesting phone call, the officer told me that they have been using it for a long time but now there is some problem that they don’t know how to fix and if the problem is not fixed, in few weeks all F15’s might be grounded so they need my help. He asked it I can help them and as always I said “Yes I can…”.
He got the budget to call me (at that time it wasn’t so easy) and the next week I came there in the morning, he welcomed me and introduced me to the other soldiers at the department. The place seemed the same as I remembered from 1989. It seemed as if time stood still or they had a time machine that returned me to 1989 :-)
I don’t remember the actual problem, I do remember it was a hardware problem, software as you probably know either works of fools you, there is no such a thing as software does not work.  I remember that I imagined a quite skies with no roaming F15 engines sound… Since I thought it might be impossible to find replacement parts for this old equipment but, we where in a place where time stood still, so it wasn’t so complicated to find the replacement parts so we could fix it and upload the software from backup diskettes I left there (it was 5.25 inch floppy disks if someone remembers them).

After everything worked again, one of the soldiers there asked me about this programming language where did I find it and what is it used for? I told him I  invented it and it is used only for this. He looked at me with an admiring look and could not believe what I told him. I opened the source code for the interpreter (written in C) and showed him my name at the head of all files. He continued asking more questions on using these software tools, some of it I did not remember but fortunately I left enough documentation files so I explained him the structure of the documentation files and how to use them.

At the end of the day I told the officer that now I could fix it, but next time we might not find replacement parts for so old and obsolete equipment so he must think about building a new one. It was just like the old times when I was at the air force he said “Ok, give me a plan and price estimation” So I spent the next days writing a plan and a quotation for building new device and of course new version of the software, this time based on Linux instead of MS-DOS.

Unfortunately he did not find the budget and this was never built. I guess today these F15 models  are also obsolete so they may not need it any more.

Anyway it was nice to remember it.


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