Linked by Eugenia Loli on Mon 9th Oct 2006 01:31 UTC
QNX Most people haven't heard of QNX Software, though they've likely come in contact with it. The real-time operating system is used where software failure can lead to catastrophic consequences, even death - from high-speed trains to air traffic control towers to highway toll systems. It's also used in more than 100 different types of cars on the road.
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RE: air-traffic is not on QNX
by djst on Mon 9th Oct 2006 09:28 UTC in reply to "air-traffic is not on QNX"
djst
Member since:
2005-08-07

I work on Air Traffic systems and have since 1995. Standard Air Force and FAA equipment. Systems run on a mix of Windows 3.11, DOS, Windows NT 4, Windows 2000, Windows 95, AIX, and Solaris (various versions). That's the recorder systems, switching systems, radar mosaic (terminal and air route), and so forth. I know of no air traffic system that runs QNX, unless it's on ROM for a specific functionality inside modems, monitors or some such. All of the primary systems are PC-controlled.

The operating systems you mention are not real time operating systems (RTOS). A RTOS can guarantee that a calculation/operation is completed within a specific time limit. Failure to complete the calculation within that time limit in a RTOS is considered a system failure, something that can have catastrophic effects.

A RTOS is often confused with fast systems (see other reply to your post) when in fact it does not have to be fast at all. The important thing is that the RTOS can guarantee that it will complete its operations in time. The fact that a deadline can be set to 50 nanoseconds or even a whole minute is not relevant.

Windows 3.11, 95, NT4, etc. are general purpose operating systems. They lack the mechanisms that allow them to guarantee that deadlines will be met. They are not necessarily slow systems, but the execution time for a calculation can vary greatly depending on (among other things) the system load.

Edited 2006-10-09 09:28

Reply Parent Score: 5

RE[2]: air-traffic is not on QNX
by Hae-Yu on Tue 10th Oct 2006 07:35 in reply to "RE: air-traffic is not on QNX"
Hae-Yu Member since:
2006-01-12

The operating systems you mention are not real time operating systems (RTOS).
I know what a real time OS is and I know the OSes I listed aren't such. The article specifically said QNX was used in ATC systems. I'm saying it's not, unless it's in a system I haven't encountered. The article is not accurate. That's all I'm saying. I know the ground systems end to end - maybe inside the airplane.

When a controller pushes a "button" on a touch screen monitor to access a channel (phone/ radio) that is a Win 3.11 PC. The headset plugs into that Win 3.11 PC and the audio is digitized in that Win 3.11 PC. The audio is piped over proprietary ISDN to a digital switch. The switch does it's work using ICs. QNX is nowhere in that system. I know of another that runs SCO Unix for the positions.

When ATCers look at their scope, they aren't looking at exactly where the planes are at. They are looking at where the central Solaris processors are predicting that plane is going to be based on heading, aircraft characteristics, speed, etc. That central processor pipes the info to a position processor also running Solaris over ethernet that powers the display. QNX is nowhere in there. The system that ingests the radar CD2 data and puts the data into a useable formaat also runs Solaris.

Unless the author can name a specific air traffic system using QNX, the article is inaccurate.

Reply Parent Score: 1