Once again, I am sure that people with more knowledge in the area can step in. It really does NOT matter if you have the transponder on or not over the Atlantice because of 2 reasons: 1. There is no radar coverage. 2. The other airplanes cannot see what your flight number is or who you are on their TCAS where the information from your transponder is used for traffic avoidance.. BAHA Fan of sunny Seattle skies today -----Original Message----- From: The Airline List [mailto:AIRLINE@xxxxxxxxxxxxxxxxx]On Behalf Of Mark Greenwood Sent: Saturday, December 06, 2003 2:57 PM To: AIRLINE@xxxxxxxxxxxxxxxxx Subject: Re: Radar If they were trying to conceal AF1's identity, would it not make sense to have the transponder off? Mark -----Original Message----- From: The Airline List [mailto:AIRLINE@xxxxxxxxxxxxxxxxx] On Behalf Of RWM Sent: Saturday, December 06, 2003 4:15 AM To: AIRLINE@xxxxxxxxxxxxxxxxx Subject: Re: Radar Why do you think the transponder was off? In any case, if it failed (or was turned off) subsequent to an IDENT having taken place, the data tag continues to move with the primary return. Even if the primary return is lost, the tag would continue to move with the predicted location based on last computed velocity vector (for up to three minutes or so, is my recollection). - RWM Mark Greenwood wrote: > > So if a blip is a blip and the transponder was most likely switched > off, would enroute ATC been given the heads up as to who they were > really dealing with in order to maintain separation, etc? > > Mark > > -----Original Message----- > From: The Airline List [mailto:AIRLINE@xxxxxxxxxxxxxxxxx] On Behalf Of > RWM > Sent: Friday, December 05, 2003 5:36 PM > To: AIRLINE@xxxxxxxxxxxxxxxxx > Subject: Re: Radar > > Correct, a blip is a blip, but no one is operating with primary radar > unless the more sophisticated secondary systems fail. When using the > secondary systems, which is hopefully 100.0% of the time, they are > looking at flight data tags, essentially "Post It Notes" attached to > the primary returns, whose data issues from flight plan data (and > manually input for pop-up traffic). Separation standards are driven > by the secondary system, using relationships between tagged traffic. > > - RWM (7N3) > -- > - R.W. Mann & Company, Inc. >> Airline Industry Analysis > Port Washington, NY 11050 >> tel 516-944-0900, fax -7280 > mailto:RWM@xxxxxxxxxx >> URL http://www.RWMann.com/ > > Floridasky@xxxxxxx wrote: > > > > A radar blip looks exactly the same for 747 and single engine > > Cessna. Believe or not flock of migrating geese will appear like an > > aircraft. In South Florida controllers call possibel traffic for > > semi trucks on I 595 on occasion not know for sure what it is. You > > can observe ships just off the coast on radar at times also. They > > all look an aircarft hit. > > > > Mike (MIA) > > --- > Incoming mail is certified Virus Free. > Checked by AVG anti-virus system (http://www.grisoft.com). > Version: 6.0.542 / Virus Database: 336 - Release Date: 18/11/2003 > > > --- > Outgoing mail is certified Virus Free. > Checked by AVG anti-virus system (http://www.grisoft.com). > Version: 6.0.542 / Virus Database: 336 - Release Date: 18/11/2003 > -- - R.W. Mann & Company, Inc. >> Airline Industry Analysis Port Washington, NY 11050 >> tel 516-944-0900, fax -7280 mailto:RWM@xxxxxxxxxx >> URL http://www.RWMann.com/ --- Incoming mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.542 / Virus Database: 336 - Release Date: 18/11/2003 --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.542 / Virus Database: 336 - Release Date: 18/11/2003 --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.542 / Virus Database: 336 - Release Date: 18/11/2003