Air traffic system failure caused by computer memory shortage • Hacker News Board

Re: Air traffic system failure caused by computer memory shortage

#31

Post by andreasvc » Mon, May 12, 2014, 10:24 AM UTC

andreasvc wrote: post #20

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.

That sounds very worrying. The fact that this issue occurs shows that they didn't prepare for OOM conditions, and another issue could easily cause a different OOM condition they didn't prepare for. It's not inconceivable that there could be an issue which gobbles up an amount of memory you throw at it. It is a tragic irony that the fact that testing is costly may be the very reason this condition was not tested for.

I can no longer edit. "an amount" should be "any amount".

Re: Air traffic system failure caused by computer memory shortage

#32

Post by twic » Mon, May 12, 2014, 11:24 AM UTC

ogig wrote: post #7

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.

I think hudibras was been sarcastic

Whereas, of course, he should have been hudibrastic [0]:

  A spyplane quietly in flight
  At angels great, not infinite
  Of course results in filling chips
  And vex'd controllers passing slips

[0] http://en.wikipedia.org/wiki/Hudibrastic

Re: Air traffic system failure caused by computer memory shortage

#33

Post by makomk » Mon, May 12, 2014, 11:37 AM UTC

hatbert wrote: post #28

cstuder wrote: post #11

Earlier quoted context omitted.

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?

One presumes they still need to know the location of those flights to deal with them descending into the range of altitudes used by commercial aircraft.

Re: Air traffic system failure caused by computer memory shortage

#34

Post by cstross » Mon, May 12, 2014, 12:51 PM UTC

makomk wrote: post #33

hatbert wrote: post #28

Earlier quoted context omitted.

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?

One presumes they still need to know the location of those flights to deal with them descending into the range of altitudes used by commercial aircraft.

No commercial aircraft operate at such altitudes. No, seriously: you run out of air for air-breathing engines above FL600 (the SR-71 flew at FL800 very fast indeed partly because it needed to go like a bat out of hell to keep enough airflow through its engines: and because it was able to go that fast due to there not being much air up there to produce drag), and the turbofans used on commercial airliners rapidly run out of wheeze above FL400.

The only civil aircraft that ever flew above FL500 were Concorde and the Tu-144, neither of which are in service. But they didn't fly at supersonic speed and high altitude in crowded airspace -- simply because getting an SST up to altitude and speed takes several minutes, a couple of hundred miles, and a prodigious amount of fuel. To say nothing of the sonic boom issue, which basically limited supercruise to over-ocean flight.

While there's been a lot of hot air about supersonic bizjets over the past two decades, so far nothing's escaped from the CAD package much less gone into flight testing.

So what you're asking for is for an FAA system to be retrofitted to handle exotic military requirements, future space shuttles, and a class of commercial aircraft that would not operate in that flight regime within a couple of hundred miles of any airport.

Re: Air traffic system failure caused by computer memory shortage

#35

Post by ape4 » Mon, May 12, 2014, 1:03 PM UTC

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.

Maybe it attempted to allocate a huge structure for each foot of altitude.

Re: Air traffic system failure caused by computer memory shortage

#36

Post by jmnicolas » Mon, May 12, 2014, 1:05 PM UTC

ars wrote: post #15

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.

> flying the most stealthy plane A U2 is not at all stealthy. You must be thinking of some other plane. > if you have to register a flight plan It's not a military operation in a foreign country, it's a routine flight in the home country. > I thought such a plane would be 100% autonomous The U2 was made long before such computers existed. They do have drones now. > and be able to "see" and avoid other planes. It wasn…

I effectively mistook the U2 and B2.

For 100% autonomous flight, I wasn't thinking no pilot, but about being able to navigate without any assistance from other radars

Re: Air traffic system failure caused by computer memory shortage

#37

Post by tomp » Mon, May 12, 2014, 1:15 PM UTC

ghshephard wrote: post #24

tomp wrote: post #22

Earlier quoted context omitted.

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

The flight was at about 60,000 feet , so it could easily have been at slightly more than 216 feet.

Re: Air traffic system failure caused by computer memory shortage

#38

Post by joezydeco » Mon, May 12, 2014, 2:03 PM UTC

ars wrote: post #15

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.

> flying the most stealthy plane A U2 is not at all stealthy. You must be thinking of some other plane. > if you have to register a flight plan It's not a military operation in a foreign country, it's a routine flight in the home country. > I thought such a plane would be 100% autonomous The U2 was made long before such computers existed. They do have drones now. > and be able to "see" and avoid other planes. It wasn…

"It's not a military operation in a foreign country, it's a routine flight in the home country"

Is it worth asking, at all, why we're flying a military reconnaissance aircraft back-and-forth over Los Angeles?

Re: Air traffic system failure caused by computer memory shortage

#39

Post by talmand » Mon, May 12, 2014, 2:23 PM UTC

makomk wrote: post #33

hatbert wrote: post #28

Earlier quoted context omitted.

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?

One presumes they still need to know the location of those flights to deal with them descending into the range of altitudes used by commercial aircraft.

They worry over them after takeoff until they ascend beyond range and once they descend into range.

I'm assuming they don't worry over satellites in orbit but they might have some concern if one decides to come back home.

Re: Air traffic system failure caused by computer memory shortage

#40

Post by khuey » Mon, May 12, 2014, 2:24 PM UTC

andreasvc wrote: post #19

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.

It's not the most stealthy plane on earth, in fact it has been shot down over the Soviet Union and China in historical cases, because of being tracked by radar. Moreover it was flying over American airspace, it makes sense to register it.

The second U2 was shot down by Cuba, not China.