View Full Version : TCAS Alert today (26-6-6)
long final
26th Jun 2006, 20:49
Whilst on manch today heard a pretty much simultaneous ATC avoid and a crew TCAS climb/descend response. Was wondering how often this situation arises?
Same thing happened to me two weeks ago!!:eek:
AlanM
27th Jun 2006, 13:32
We get about one per week on our sector at least - the beauties of descending aircraft in the TMA to 3000ft and having unknowns below at 2500ft unverified.
long final
27th Jun 2006, 17:20
Thanks for the replys. The situation I heard had the two aircraft around FL160. Not sure if one or both were descending/climbing at the time of the call.
AlanM - Interesting that you say you have at least one a week in your sector. Scary really for us guys without TCAS. Just what I was thinking as we were sat IMC at FL190 knowing we will not get the warning if it happened to us :sad:
alexban
28th Jun 2006, 11:03
As far as I know,the TCAS is mandatory in controlled airspace,isn't it?
One should reduce ROC/ROD when approaching cleared level,by this decreasing the risc for an RA..
Treetopflyer
28th Jun 2006, 14:38
TCAS not required for all a/c in controlled airspace (only if MTOW > 5,7 t or > 19 pax seats).
alexban
29th Jun 2006, 09:41
what would be the reason to not request TCAS on planes <5.7 T or <19 pax?
No danger to airliners?:} ...I doubt that..
In my area of operation,except aerobatic planes,all planes I've flown or I know about have TCAS installed on them,if flown in controlled airspace. They usually select A2000 ,if flying VFR ,if my memory doesn't play tricks on me.
Denti
29th Jun 2006, 16:42
TCAS is quite expensive and i doubt that small GA aircraft have it, a transponder however is normally required in controlled airspace and that is quite enough to generate warnings in aircraft that are TCAS equipped (please use mode c/s though).
ShyTorque
29th Jun 2006, 22:18
what would be the reason to not request TCAS on planes <5.7 T or <19 pax?
No danger to airliners?:} ...I doubt that..
In my area of operation,except aerobatic planes,all planes I've flown or I know about have TCAS installed on them,if flown in controlled airspace. They usually select A2000 ,if flying VFR ,if my memory doesn't play tricks on me.
I think you are referring to a Transponder, rather than TCAS, Alexban.
TCAS detects the presence of transponder equipped aircraft by interrogating them. ;)
BTW, in our job we sometimes get three or four TCAS advisories on a sector!
Tarq57
30th Jun 2006, 01:26
A few months ago I was part of the tower team involved in the situation OP asked about. A VFR aircraft (with a clearance) took off from an area shielded from ATC radar. The clearance should have resulted in it being seperated from the final approach. When first observed on our radar display it popped up on final, going the other way, indicating a climb through 1000ft. There was a B737 on the ILS at 12 o'clock, 3nm, descending through about 1700ft. The surprised aerodrome controller reacted in what seemed like nanoseconds, and as the Boeing pilot acknowledged the climb/MAPP instruction she also reported "TCAS climb". I found that fairly reassuring from the viewpoint that it would have prevented a (likely) collision, had no climb instruction been issued.
My friends on area control tell me that TA's are fairly common, and RA's used to happen in the situation where an aircraft is about to level off with someone above/below coming the other way, probably because of the much higher closure rate. They seldom seem to happen near the aerodrome. Think I've seen about 1 or 2 a year, and only 1 total where there was an actual loss of seperation.
Treetopflyer
1st Jul 2006, 08:04
Originally Posted by alexban
what would be the reason to not request TCAS on planes <5.7 T or <19 pax?
JAR-OPS regulations, maybe... :hmm: Have you seen many Cessna Caravans, Piper Navajos or BN Islanders equipped with TCAS???
Originally Posted by alexban
No danger to airliners? ...I doubt that..
Danger to airliners? No: theses planes are all transponder-equipped, so your TCAS will alert you before you smash one with your Boeing. In effect, only two small planes (MTOW < 5.7t etc) can collide without alert, I guess some people decided that wouldn't be too much of a tragedy...
Danger to airlines? Definitely! How many small aircraft operators would go bankrupt if TCAS was required on ALL commercial aircraft flying in controlled airspace??? How much does it cost to install TCAS on a 200,000 € piston twin??? :rolleyes: :ugh:
Tarq57
1st Jul 2006, 08:25
Must say I am frequently surprised, but then not really, at the number of aircraft blatting around with the transponder off or alpha only selected.
See them on the screens all the time.:uhoh: