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Air traffic system failure caused by computer memory shortage

reuters.com

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Re: Air traffic system failure caused by computer memory shortage

#21

Post by lyndonh »

awjr wrote: post #6

Having worked on ATC, this really does sound like a software bug. Fixing such a bug on a delivered system would require an immense amount of costly testing. Adding memory is the cheap option. The other thing to consider is that some of these systems are rather old and could easily have less than a gig of ram.

> Adding memory is the cheap option

Only in the sense of having a broken system, putting in place some procedural constraints and then praying that everyone follows the rules.

As you say, it's a software bug. Until it's been 100% characterised and tested this leaves a huge question mark hanging over the system. Adding memory is a band aid solution.

Re: Air traffic system failure caused by computer memory shortage

#22

Post by tomp »

damian2000 wrote: post #2

Sounds more like a bug rather than a lack of memory to me ... The flight plan did not contain an altitude for the flight, one of the sources said. While a controller entered the usual altitude for a U-2 plane - about 60,000 feet - the system began to consider all altitudes between ground level and infinity. The conflict generated error messages and caused the system to begin cycling through restarts.

  unsigned short int altitude;

Re: Air traffic system failure caused by computer memory shortage

#24

Post by ghshephard »

tomp wrote: post #22
damian2000 wrote: post #2

Sounds more like a bug rather than a lack of memory to me ... The flight plan did not contain an altitude for the flight, one of the sources said. While a controller entered the usual altitude for a U-2 plane - about 60,000 feet - the system began to consider all altitudes between ground level and infinity. The conflict generated error messages and caused the system to begin cycling through restarts.

unsigned short int altitude;

The flight was at 60,000' - You would have to look far and wide for a platform in which "short int" wasn't two bytes.

For example, Here is what the compiler for the 8-bit ATMEL Atmega 328 in an arduino does (on a platform with 32KB for program text and 2KB for RAM.)

  sizeof(bool) == 1
  sizeof(short) == 2
  sizeof(int) == 2
  sizeof(long) == 4
  sizeof(long long) == 8
  sizeof(void *) == 2

Re: Air traffic system failure caused by computer memory shortage

#25

Post by venomsnake »

hudibras wrote: post #3
damian2000 wrote: post #2

Sounds more like a bug rather than a lack of memory to me ... The flight plan did not contain an altitude for the flight, one of the sources said. While a controller entered the usual altitude for a U-2 plane - about 60,000 feet - the system began to consider all altitudes between ground level and infinity. The conflict generated error messages and caused the system to begin cycling through restarts.

They didn't have enough memory to cope with an infinite number of inputs. Obviously a hardware problem...

Also how dare they not to have cpu that can run infinite cycle in under 2 seconds.

Re: Air traffic system failure caused by computer memory shortage

#26

Post by huhtenberg »

andreasvc wrote: post #16
huhtenberg wrote: post #8

I would guess that it was some form of an numeric overflow, signed/unsigned issue or out of bound array access, because the only abnormal thing here is U2's altitude.

Have you read the article? The cause is explained quite explicitly, and it was the very absence of the altitude not any of the things you mention.

> very absence of the altitude

And? Consider what this means exactly and how come the system saw the plane but didn't record the altitude.

Re: Air traffic system failure caused by computer memory shortage

#27

Post by venomsnake »

jmnicolas wrote: post #12

What's the point of flying the most stealthy plane on earth if you have to register a flight plan ? I thought such a plane would be 100% autonomous and be able to "see" and avoid other planes.

A good idea when you consider that it could be mistaken for some bad guys plane, shot down and probably cause WWIII (not that long shot - the US and USSR were at a few times very close to annihilation due to glitches in their own software)

Re: Air traffic system failure caused by computer memory shortage

#28

Post by hatbert »

cstuder wrote: post #11
gonzo wrote: post #4

Earlier quoted context omitted.

is there a plane that flies at infinite altitude? Is there an aircraft of concern to the FAA that flies above FL1000? One or two historic flights have been that high, so raise the ceiling to 150,000' still not infinite.

Yeah, let's hardcode a maximum altitude somewhere deep in the code and be completely surprised when, a couple of years in the future, newer, higher-flying planes/shuttles disappear from the system.

Well, considering that altitudes above FL1000 have been, for the last 60-odd years, considered to be outside the FAA's jurisdiction... what is the problem exactly?

Re: Air traffic system failure caused by computer memory shortage

#29

Post by atlantic »

So much talk about Snowden, and then a newspaper reveals how to trigger a software bug than can shut down the entire air traffic control system for a large segment of the US. This is a genuinely damaging revelation, even if some critical details are lacking. Curious that the government is not up in arms about it.

Re: Air traffic system failure caused by computer memory shortage

#30

Post by prof_hobart »

jmnicolas wrote: post #12

What's the point of flying the most stealthy plane on earth if you have to register a flight plan ? I thought such a plane would be 100% autonomous and be able to "see" and avoid other planes.

If you don't register military flights on civil ATC systems, you run the risk of this -http://en.wikipedia.org/wiki/Hughes_Airwest_Flight_706
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