Null references (oh no, not again!)

[Sean Kelly]

Georg Wrede wrote:
> Nick Sabalausky wrote:
>> "Walter Bright" <newshound1 at digitalmars.com> wrote:
>>> I started my career doing flight critical mechanical designs for 
>>> Boeing airliners. I had it pounded into me that no matter how perfect 
>>> you designed the parts, the next step is "assume it fails. Now what?" 
>>> That is why Boeing airliners have incredible safety records.
> 
> Yup. That's what McDonnell didn't do with the DC-10. They were crashing 
> mysteriously in mid-fligt, and nobody survived to tell.
> 
> The DC-10 had three entirely separate steering systems: a mechanical (as 
>  in wires from cockpit to ailerons), a hydraulic one, and an electrical 
> system.
> 
> After a superior pilot(1) actually brought his plane home after disaster 
> struck, it was found out that the reason to all the crashes was a cargo 
> door lock, which could be shut carelessly and then, if the ground guy 
> was strong enough, lock the latch by force, leaving it only partly 
> locked. Once in the air, the airpressure blew the door open, resulting 
> in the passenger floor collapsing, and shredding the steering systems.

At Newark Airport in New Jersey, the Air Control Tower's network is 
linked to radar and such via redundant cables, as expected.  However, 
these cables are run right next to one another, eliminating any benefit 
that the redundancy might provide.  Funny how things change between the 
design requirements and implementation.