6 ms·
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 cont
by damian2000 12y ago
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.
- hudibras 12y agoThey didn't have enough memory to cope with an infinite number of inputs. Obviously a hardware problem...
- gonzo 12y agois 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.
- ogig 12y agoI think hudibras was been sarcastic
- twic 12y agoWhereas, 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 http://en.wikipedia.org/wiki/Hudibrastic
- cstuder 12y agoYeah, 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.
- andreasvc 12y agoNo one said anything about burying it, it can be at the top of the main configuration file if you insist. The basic problem is that one quantity was limited (memory), without dealing with another (altitude). It makes perfect sense to limit both, while you're at it. But of course most important of all, test and study the effects of going over those limits ...
- hatbert 12y agoWell, 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?
- makomk 12y agoOne 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.
- cstross 12y agoNo 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.
- venomsnake 12y agoAlso how dare they not to have cpu that can run infinite cycle in under 2 seconds.
- MattHeard 12y agoIt sounds like the altitude existence assumption caused cascading errors which in turn exhausted the system memory.
- ars 12y agoThat's not what the article said. They said that since it didn't know the true altitude the computer assumed the plane could be at every altitude, and checked every single possible one. This was made worse by a flight plan that had the plane going in and out of the area, so there were a tremendous number of permutations of possible flight paths. The computer attempted to allocate memory to calculate every one of them and ran out of memory.
- vince_refiti 12y agoThis scenario wasn't unit/functional tested then.
- tomp 12y agounsigned short int altitude;
- ghshephard 12y agoThe 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
- tomp 12y agoThe flight was at about 60,000 feet , so it could easily have been at slightly more than 216 feet.
- ape4 12y agoMaybe it attempted to allocate a huge structure for each foot of altitude.