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Questions tagged [tcas]

Traffic Collision Avoidance Systems warn pilots about other, nearby aircraft that may be a collision risk

A traffic collision avoidance system, or traffic alert and collision avoidance system, (both abbreviated as TCAS and pronounced tee-kas) is a system designed to reduce mid-air collisions between aircraft.

TCAS units use transponder signals to gather information about nearby aircraft. If two aircraft are on a collision course, their TCAS units communicate with other to negotiate an avoidance plan, e.g. one aircraft climbs and the other descends. The unit then alerts the crew with a spoken warning or instruction such as "climb, climb!". Crews are required to follow the TCAS instruction immediately, even if ATC has given other instructions.

ICAO mandates TCAS for all aircraft that have a maximum take-off mass (MTOM) of over 5,700 kg (12,600 lb) or are authorized to carry more than 19 passengers.

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What is the range of TCAS?

The traffic collision avoidance system has two versions, TCAS I and TCAS II. I know for sure that TCAS I has a range of 40 nautical miles, but what is the range for TCAS II?
Gianni Alessandro
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When receiving a TCAS RA, DESCEND DESCEND, and starting the descent, if a pilot received GPWS warning, TERRAIN, what would they do?

The TCAS warning says: " DESCEND, DESCEND" and immediately after the crew receives: "TERRAIN, TERRAIN", what would they do?
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In what scenario would a "climb, crossing climb" or "descend, crossing descend" be issued by a TCAS system?

"CLIMB, CROSSING CLIMB, CLIMB CROSSING CLIMB" "DESCEND, CROSSING DESCEND, DESCEND CROSSING DESCEND" (TCAS Aural Alerts - Padpilot, Advanced Instrumentation) In what situation would a TCAS system advise a climb or descent thorough another…
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Can a drone be seen on TCAS?

On condition that the pilot reports to ATC, an aircraft's TCAS sees a drone in the vicinity. How can the pilot be sure that it was a drone on TCAS? What kind of symbol is shown on TCAS that can be identified as a drone? Or is it just a primary radar…
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Does the RA (resolution Advisory) from TCAS II take into account the stall margin required?

A resolution advisory from TCAS indicates the vertical speed per minute that you must use to avoid conflict with the other traffic. Does this vertical speed given by the RA take into account the stall requirement for the aircraft?
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How does the TCAS decide which aircraft to climb and which to descend

In practice, how does TCAS decide which aircraft to climb and which to descend; or what factors does it take into account.
eggplant
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Can you have TCAS RA if your other traffic only have TCAS TA?

If you fly and have a TCAS TA, it announce "TRAFFIC, TRAFFIC!" However, the other traffic executed a TCAS RA and did the "UNKNOWN" manouvre. Is it possible? As what i remember, it does takes two aircraft in RA mode. Unless you selected TA MODE…
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What is the need for TCAS?

Isn't it the job of the air traffic controller to assign altitudes and make sure airplanes do not collide in mid-air? Is having TCAS mandated or optional? If it is a mandate, then is there a mechanism to notify other airplanes that TCAS is off?
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What RA will be generated if intruder traffic is at our level in TCAS II?

If the other traffic is at the same level, and neither climbing or descending. Will the RA say "CLIMB" or will it say "DESCEND"? How will it be decided and what are the possibilities? Assume: Mode S is not available Only one aircraft has TCAS Will…
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TCAS II - bottom omni-directional antenna

I know that the TCAS II system has a lower antenna which can be either omnidirectional or directional. How does the functionality of the system change? If the antenna is omni then I think / assume that it cannot know the bearing of an intruding…
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Could TCAS be overwhelmed by multiple conflicting traffic and "give up"?

I understand that TCAS can handle several "targets" simultaneously. However, I'm interested in the (highly hypothetical) scenario where TCAS would need to deal with multiple conflicts in a dense environment. Is there a point where TCAS goes into…
user12873
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How is the TCAS negotation information encoded?

As I understand, according to this FAA booklet on TCAS, transponders will engage in cycles of interrogations and responses to establish if a collision may occur. The next step is for both TCAS systems to negotiate respective resolution advisories.…
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Is a TCAS capable of handling three (or more) planes on "crash course"?

I asked myself if the TCAS is capable to handle, the very unlikely situation, that three (or more) planes are simultaneously on "crash course" (Sorry, got no other word for it). If not, how would the TCAS "react"? Thanks.
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How much time do pilots have to execute a TCAS Resolution Advisory?

The Wikipedia entry for TCAS (Traffic collision avoidance system) states for resolution advisories (RA): "When an RA [Resolution Advisory] is issued, pilots are expected to respond immediately to the RA unless doing so would jeopardize the safe…
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Can a TCAS or Marker beacon antenna be installed inside a radome?

I was wondering how sensitive these systems are. We are planning a modification which will involve either moving these antennas or leaving them in place under a radome (the radome is designed for x-band frequencies)
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