Air traffic control problems

[whole diary]

[TaplowGreen]

Nice touch by LNER^» (London North Eastern Railway - about) following yesterday's problems (the fallout from which is ongoing)

[IndustryInsider]

All caused by a single rogue flight plan apparently!

[stuving]

All caused by a single rogue flight plan apparently!

Depends what you means by "caused". I'd expect a system like that to be 100% protected against bad input data, not to declare a serious internal error nor for it to take hours for its minders to work out that's what happened. That's what caused the damage.

[ellendune]

All caused by a single rogue flight plan apparently!

Sounds like an error trapping fault in the software. 

[grahame]

All caused by a single rogue flight plan apparently!

Sounds like an error trapping fault in the software. 

It seems astonishing, especially in a system which should have been tested virtually out o existence - however, I can look back at a life working with software and tell some stories.

I was responsible for a batch / record keeping system where we updated our main tape "file" every few days - a pile of punched card updates grew n our office, and once it reached a line on the wall behind the table, we submitted a job.  Occasionally we ran it "short" for an urgent update, or delayed it if the computers were too busy with customer production work - and the update pile grew even to several times the normal height.   Worked perfectly, no problems.  For years.

Then one day the data "corrupted" - the output printout showed that the tape file had not been updated  It had been initially tested, running for years, trusted to work every time ...  what the *** had happened?

It turned out that if the number of input records was a multiple of 427, then the last 427 records were ignored.  The line on the wall was at around 350 and usually there wasn't even one "set" of 427.  At very busy times, two updates tended to be combined and it ran with around 700 updates. Perfect.   Then one day ...

The bug was a ".GE." rather that a ".GT." (or was it the other way?) deep in the code ... records were sorted in batched prior to the update. There was a buffer of 50000 bytes and a record size of 117 bytes and if it got full but didn't trigger a new buffer we had a problem. The number "427" was no-where in the code.

I don't know what happened at NATS - but I have an element of sympathy.   Of course, it has got more complex these days and it sounds like the system and feedback loops (lacking in our system 50 years ago) rang alarm bells ....

[bobm]

If the safety of my flight depended on a pile of punched cards against a wall I think I’d walk.

However joking aside I suspect going back there were a number of what we now call safety critical systems that did operate on a bit of a wing and a prayer in the early days.

[IndustryInsider]

Lots of similar examples over the years.  I’d rather have them fail safe than carry on regardless as in the case of the Therac 25 machines of the 80s.

[broadgage]

If the safety of my flight depended on a pile of punched cards against a wall I think I’d walk.

However joking aside I suspect going back there were a number of what we now call safety critical systems that did operate on a bit of a wing and a prayer in the early days.

True, but it must be said that AFAIK^▸ (as far as I know), not a single aircraft crashed as a result of this failure, certainly no lives were lost (unless you include heart attacks and the like resulting from stress at the delays). Every single aircraft that was already in the air landed safely.
I remain opposed to air travel in all but exceptional cases, but that is due to climate change, not fear of accidents.

[PrestburyRoad]

I too am not worried about aircraft crashing when I fly, but I am ever more inclined to avoid air travel due to the tedious waiting, queuing and herding that's involved nowadays before and after a flight, including the faff of getting to and from the airport.  A 2-hour flight often has a door-to-door time of 10 hours for me - that's two daysworth of tedious overhead when taking a holiday.  Then add in the environmental impact of flying, and I'm becoming increasingly inclined to stay in Britain - there's so much to enjoy here.

[eXPassenger]

I have seen a comment that the system is designed that if there is a significant data input problem then it will fail safe by reverting to manual.

In this case fail safe prevented a lot of flights.

[TaplowGreen]

Sums it up quite well!!!

[broadgage]

I presume that aircraft are exempt from the ULEZ rules and can fly over the relevant areas without restriction.

[paul7575]

Willie Walsh quoted by almost any news source:

“… questioned whether the firm should continue to hold responsibility for handling the UK^▸ (United Kingdom)'s flight traffic.”

Is there a spare complete ATC^▸ (Automatic Train Control) system somewhere, (with suitable staff just sitting around waiting), ready to be switched on?   

Paul

[TonyK]

I too am not worried about aircraft crashing when I fly, but I am ever more inclined to avoid air travel due to the tedious waiting, queuing and herding that's involved nowadays before and after a flight, including the faff of getting to and from the airport.  A 2-hour flight often has a door-to-door time of 10 hours for me - that's two daysworth of tedious overhead when taking a holiday.  Then add in the environmental impact of flying, and I'm becoming increasingly inclined to stay in Britain - there's so much to enjoy here.

A two-hour flight will take you about 1,000 miles, which isn't bad for 10 hours. It all depends on where you want to go.

[broadgage]

A fast and direct train could take you 1000 miles in 10 hours, in greater comfort and with less stress than air travel.
Even better if it was a sleeper train.