nanog mailing list archives
RE: Analysis from a JHU CS Prof
From: "Deepak Jain" <deepak () ai net>
Date: Thu, 13 Sep 2001 17:34:18 -0400
It is my understanding that the planes were _always_ on Radar, but that without the transponder, the altitude of the planes was unknown. DJ -----Original Message----- From: owner-nanog () merit edu [mailto:owner-nanog () merit edu]On Behalf Of Leigh Anne Chisholm Sent: Thursday, September 13, 2001 5:11 PM To: Borger, Ben; nanog () merit edu; Hire, Ejay Subject: RE: Analysis from a JHU CS Prof I despise posting off-topic, but I want to say two things... 1. If a transponder is turned off, it doesn't mean that you don't show up on radar--a blip appears on the radar screen as long as you're high enough to be detected. If however you fly low enough, you can fly below the radar's detection capability. I don't offhand recall what height that is--it's been years since I was active as a pilot and prospective Air Traffic Controller. 2. What's the point of having transponder codes for hijacking if they're so well published everyone is aware of them? The purpose of the codes was so that the pilot could communicate this information without the hijacker becoming aware of what was happening. I have always REALLY DISLIKED the now common practice of advertising this information. You're taking away one of the pilot's best tools... -- Leigh Anne
-----Original Message----- From: owner-nanog () merit edu [mailto:owner-nanog () merit edu]On Behalf Of Hire, Ejay Sent: Thursday, September 13, 2001 2:35 PM To: 'Borger, Ben'; 'nanog () merit edu' Subject: RE: Analysis from a JHU CS Prof The transponders, like most avionics, has a handy-dandy off switch. -----Original Message----- From: owner-nanog () merit edu [mailto:owner-nanog () merit edu]On Behalf Of Borger, Ben Sent: Thursday, September 13, 2001 2:32 PM To: 'nanog () merit edu' Subject: FW: Analysis from a JHU CS ProfAt 06:05 PM 9/12/2001, you wrote: Quite more interesting is why nobody noticed that 4 airliners wherehijackedalmost the same time.Not surprising. Aircraft are "flight followed" by a series of control centers across the nation, each responsible for a given chunk of airspace. Something happening in an area controlled by Center "A", for example, wouldn't be passed on to Center "B" (which has it's ownproblemsto work) unless it impacted Center "B". Furthermore, unlesssomeone TELLSCenter they're being hijacked, there's no way for a controller -looking ata blip - to know what's up. And any controller can tell youthat pilots do Somehow the people who did this managed to turn off the transponders on these planes. Normally a plane flying in controlled airspace squawks a unique id and altitude which is decoded by their radar and associated with each blip. Sometimes low cost homebuilts/ultralights fly with no transponder, but Boeings <sarcasm>usually</sarcasm> do. If you set a transponder to XXXXX, it means you're being hijacked. BTW if you see your friend Jack at the airport, be sure to say, "What's up, Jack!" instead of "Hi Jack!" So how do you deal with this? Blowing up a whole country? I wonder if the US should adopt a 'fire w/ fire' approach and invest in intelligence, covert ops and assassinations. It would seem that it is open season on terrorism by every democratic nation, I expect to see very conspicuous Samuel Jackson style ass whoopins on whiny extremist groups to satiate America's anger. Terrorize the terrorists. Oh yeah, obviously Echelon should probably have MacOS loaded on it. -b
Current thread:
- RE: Analysis from a JHU CS Prof, (continued)
- RE: Analysis from a JHU CS Prof Deepak Jain (Sep 12)
- RE: Analysis from a JHU CS Prof Hire, Ejay (Sep 12)
- Re: Analysis from a JHU CS Prof David Lesher (Sep 12)
- RE: Analysis from a JHU CS Prof Ron Buchalski (Sep 12)
- RE: Analysis from a JHU CS Prof Deepak Jain (Sep 13)
- Re: Analysis from a JHU CS Prof Joel Baker (Sep 13)
- RE: Analysis from a JHU CS Prof Deepak Jain (Sep 13)
- RE: Analysis from a JHU CS Prof Borchers, Mark (Sep 13)
- FW: Analysis from a JHU CS Prof Borger, Ben (Sep 13)
- RE: Analysis from a JHU CS Prof Leigh Anne Chisholm (Sep 13)
- Re: Analysis from a JHU CS Prof Jeff Mcadams (Sep 13)
- RE: Analysis from a JHU CS Prof Deepak Jain (Sep 13)
- Re: Analysis from a JHU CS Prof Joel Baker (Sep 13)
- RE: Analysis from a JHU CS Prof Matt Levine (Sep 13)
- RE: Analysis from a JHU CS Prof John Fraizer (Sep 13)
- RE: Analysis from a JHU CS Prof Leigh Anne Chisholm (Sep 13)
- Re: Analysis from a JHU CS Prof Owen DeLong (Sep 13)
- Re: FW: Analysis from a JHU CS Prof Majdi S. Abbas (Sep 13)
- RE: Analysis from a JHU CS Prof Matt Levine (Sep 13)
- RE: Analysis from a JHU CS Prof Mikael Abrahamsson (Sep 13)
- RE: Analysis from a JHU CS Prof Leigh Anne Chisholm (Sep 13)