Don, while I realize it's not the main part of your post, I disagree with
your descriptions of air traffic control.

First, "IFR" is "Instrument Flight Reference." This is only flown when
visibility is low, such as when you are in clouds. It has nothing to do with
controllers - only the weather, and the need for the pilot to be IFR
certified. You can be IFR out in the middle of the Pacific where there is no
air traffic control. Controllers often assist in IFR conditions, but by no
means are airplanes under IFR conditions just because they are commercial or
because they are in controlled airspace. In fact, you really want to avoid
IFR whenever you can.

"VFR" is what you fly on clear days - "Visual Flight Reference". But once
again, nothing to do with controllers, just the fact that you only need to
look out the window to avoid the ground.

You're only controlled in controlled airspace. It's perfectly alright to be
dead silent for minutes or hours at a time in these areas. Ever listened to
the pilots on one of those on-board earphones? They can go hours with no
contact. If each of the 40K flights a day was talking every 5 minutes, the
channels would be jammed completely. You only talk when required by some
condition of flight or when you are asked a question.

I've flown private planes with my dad (I'm not a pilot, he is), and I have
many friends and a brother that are commercial pilots. The only time you
really talk a lot is during takeoff and landing when you are in the densest
of controlled airspaces. After that, you are cleared on your flight plan and
set free. No need to talk after that until you approach your destination, or
intermittently as you cross certain boundaries.

Finally an "off" transponder is not suspicious. First, they get turned off
on accident all the time, or they fail, so that is the first assumption.
Second, they need to be off for a while before the system really comes to
the conclusion that the transponder is no longer squawking. It's not like
the radar has a constant link with the transponder, so it being turned off
is not instantly apparent to those on the ground.

--Ian

----- Original Message -----
From: "Don Hyde" <DonH@AXONN.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Wednesday, September 12, 2001 3:39 PM
Subject: Re: [OT]: Disabling hijacking?


> > 1000s of planes in the air corridor over the east. Literally
> > impossible to tell if one not near an airport is doing something
> > a little funny. No time to figure it out, and react [shoot down]
> > in the time frame in question. Plus plane goes straight into the
> > gnd, forms a deep 30' x 30' crater, not blown into bits 30,000
> > feet in the air.
> > =============
>
> There are only about 3000 airliners in the country, and a lot of them are
on
> the ground loading and unloading at any one time.  They always fly "IFR",
> which means that they are in constant contact with air traffic
controllers.
> If they don't hear from an airliner for 5 minutes, a controller will
already
> be wondering if something's wrong.  Airliners (and the vast majority of
> other planes) have transponders, that send back a code when they are
> "pinged" by radar.  This code helps the FAA's 50-year-old computers draw a
> "shrimp boat" with the flight number next to the dot on the screen.  The
> first thing a pilot does at the first hint of a hijacking is to switch the
> code on the transponder to a special one that says "I've been hijacked".
> This sets off bells and whistles and stuff on the controller's console.
> Supposedly the first thing the hijackers did was turn off the transponder,
> but that would only make it more suspicious.
>
> No, air traffic controllers knew within a couple of minutes that the
planes
> were hijacked, and they had them on radar, so they knew where they were
and
> which way they were headed.
>
> Usually hijackers make some sort of demands and want to be taken
somewhere,
> so standard procedures work on that assumption.  Humor the nut, and you
can
> probably talk him down somewhere and nobody gets hurt.
>
> These guys had a new strategy.  We haven't had hijackers grabbing the
> controls and diving the plane into some target before, so the standard
> procedures didn't work.
>
> The new tactic apparently worked for, at most, an hour.
>
> Someody had wised up.  Maybe it was the Air Force and they shot the plane
> down.  It's starting to sound like it was the passengers and crew who
> figured out that, unlike the usual kind of nut, with these lunatics, the
> best strategy was to fight back, even if it meant everyone on the plane
> died.
>
> I think we may have had a planeload of ordinary folks who behaved like
> heroes and taught us all a new paradigm for dealing with hijackers.
> Heightened airport security or not, I don't think a tactic like the one
> these guys used will ever work as well as it did this time.
>
> --
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>

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