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- Thread starter USN_ATC
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Nope, not new. It's been around for at least 12+ years. But unless your plane has TCAS II, I doubt if you have it.Punk said:
Mode S lets transponders exchange information with each other via a data link. It's allows two aircraft equipped with TCAS II to exchange information and give avoidance guidance in response to Resolution Advisories. Aircraft with Mode C transponders can only give Traffic Advisories with no escape manuever guidance (TCAS I). After an Air Force C-141 had a mid-air in the South Atlantic sometime in the mid-1990s, there was a big push to give all transport aircraft TCAS. I don't know if it was I or II but would assume it was TCAS II / Mode S. I would also assume that the Navy's 737s would have it since they are new and because airlines are required to have it. It would probably cost Boeing more to revert back to TCAS I / Mode C than give the Navy the newer stuff.gatordev said:
Mode S ATC X-ponder
The S in Mode S X-ponders stands for "selective" so groundstations (ATC) can interrogate the X-ponder onboard flying Aircraft, retrieving data like Flt Lvl, Grndspd, Squawk, A/C type without any fltcrew action. TCAS is also using data but the main goal of mode S was reducing ATC comms and stay well informed in highly crowded airspaces.
The S in Mode S X-ponders stands for "selective" so groundstations (ATC) can interrogate the X-ponder onboard flying Aircraft, retrieving data like Flt Lvl, Grndspd, Squawk, A/C type without any fltcrew action. TCAS is also using data but the main goal of mode S was reducing ATC comms and stay well informed in highly crowded airspaces.
Close. Groundspeed is computed by the ATC computers based on the radar return or transponder return. Mode S provides ATC ground stations and other aircraft altitude, discrete address and transponder code. The discrete address is the aircraft ID, normally its side number. When providing TCAS II Resolution Advisory escape maneuver recommendations, the Mode S transponder will also tell the other aircraft it's planned avoidance maneuver (i.e. climb or descent). The other aircraft's TCAS II than gives it's pilots the opposite maneuver (very simplified version of the events). The TCAS II / Mode S transponders continue to coordinate escape maneuvers until the aircraft are satisfactorily deconflicted. ATC does not participate in this conflict resolution and it's computers do not get any of the advisory alerts or escape recommendations. However the pilot is required by FAR to follow this guidance, we just tell ATC over the radio either while it's happening or after it's over. From what I have been able to gather from talking to ATC folks, they don't really care if an aircraft has Mode C or S. Mode S gives a little better altitude readout and allows them to ID aircraft if there is a violation. That's about it and it really doesn't effect their day-to-day controlling. The FAA mandates Mode S because of the TCAS II requirement.nkawtg said:
There was supposed to be a follow on TCAS III where the systems would add the horizontal plane to the escape maneuvers. The Mode S data link is capable of transmitting this info too with the proper software change. So far this has not happened.
ATC's goal with Mode S was originally a system where they could provide headings, altitudes, etc over the data link vice voice. It will be a long time before this ever happens if at all.
Thanx HAL for the detailed info.
On our Airframe, Boeing (in consult with the FAA) called out an AD-Note that as from jan 2007 all our aircraft should be Mode S equipped when entering US airspace. It might be broken/not working, but must be installed......the show must go on!
On our Airframe, Boeing (in consult with the FAA) called out an AD-Note that as from jan 2007 all our aircraft should be Mode S equipped when entering US airspace. It might be broken/not working, but must be installed......the show must go on!
nkawtg said:
Of course having an airborne radar w/ CIT can give you all the TCAS info on other birds without giving your info to the network.
For the curious:
http://www.fas.org/irp/program/security/_work/kiv-6.html
One of the Tomcat pictures....the one with the shark mouth that looks like it was drawn on with a magic marker....is a VF-211 aircraft, judging by the helmet job. I put alot of those damn checkers on helmets in my Airman days. I do question if it is actually a VF-211 bird though seeing as how there shouldn't be any of them anymore....but what do I know.