Subject: Re: OT: This system must have been written in Ruby...
From: (Rob Warnock)
Date: Fri, 06 Mar 2009 03:12:47 -0600
Newsgroups: comp.lang.lisp
Message-ID: <>
Kenneth Tilton  <> wrote:
| Rob Warnock wrote:
| > And guess what?!? The Dutch Safety Board says that the Turkish Airlines
| > plane *was* on an autoland approach when the altimeter failed!
| >      According to the Flight Data
| >      Recorder, the airplane was on a full autoland approach at a
| >      height of 1950 ft / 595 m when the left Radio Altimeter suddenly
| >      misreported a height of -8 ft. The autoland system responded
| >      accordingly...
| yeah, what am I gonna do?, the altimeter says 1950 then it says -8, I 
| have to respond accordingly--I ignore the broken altimeter!!!!!!

Of course, if you're landing on Catalina Island:,_California
    Catalina's airport, the "Airport in the Sky" (AVX), was completed
    in 1946. The 3,250-foot (990 m) runway sits on a mountaintop,
    1,602 feet (488 m) above sea level.

then the radar altimeter going from 1,602' to -8" instantly would
be perfectly *normal*!! The approach end of the runway extends all
the way to the edge of the cliff, you see:
    The approach end of Catalina's runway 22 begins at the edge of a
    1500' cliff. This gives the airport some characteristics similar
    to landing on an aircraft carrier that is 1,602' in the air.

[Yes, I know that AVX isn't approved for Cat IIIc approaches... ;-}
In fact, all it has are two circling approaches, VOR-A (GPS-A)
and VOR/DME (GPS-B), and those are only approved for planes which
land slower than 120 kts. But still...]

| I am telling you, the software had plausibility checks.

No argument. But I'm just saying that getting the plausibility checks
"right" isn't trivial. You'd need a database for each possible approach
type to each possible runway at each possible airport at which you might
attempt a landing. And then you'd have to debug the database... and then
keep it current with any new construction around each airport... etc.


Rob Warnock			<>
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