Greek TCAS incident & query re Automatic Collision Avoidance System
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Having a RA with an airliner it's a bit different than that with a military fighter jet. I've know of a 747 cpt having a RA with a Mig21,just before the jet launched for supersonic flight,RA that caused injuries to a nr of pax and FA.
You can get very fast a 'climb,climb ' command followed by a fast 'descent,descent' ,due to high speed and manouvrability of the fighter jet .
I guess the fighter pilots should be trained,and told about the risks involved in playing 'targets' with the airliners,cause there are a lot of pax and crew walkind,standing in those planes.
Luckily for the Olympic they were descending,with the fasten belts sign on,i guess...
You can get very fast a 'climb,climb ' command followed by a fast 'descent,descent' ,due to high speed and manouvrability of the fighter jet .
I guess the fighter pilots should be trained,and told about the risks involved in playing 'targets' with the airliners,cause there are a lot of pax and crew walkind,standing in those planes.
Luckily for the Olympic they were descending,with the fasten belts sign on,i guess...
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Originally Posted by GreekPilot747
B737 climbed 1000 ft within 2 seconds.
That would mean, they arrested the descent and climbed 1000ft within
2 seconds.
Now if you calculate that, you end up with a climbrate in excess of 30000 fpm.
How realistic is that, and what would be the g-forces implied?
That would mean, they arrested the descent and climbed 1000ft within
2 seconds.
Now if you calculate that, you end up with a climbrate in excess of 30000 fpm.
How realistic is that, and what would be the g-forces implied?
Probably more of a quick change of direction with all the momentum related mishaps on board.
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Captain Pit Bull,
I think I mis wrote what I meant to say!!
TCAS is a useful tool in helping with the situational awareness, if used correctly, as you said.
Alexban
UK forces are no longer allowed to 'embellish' civil A/C. I don't know about overseas
I think I mis wrote what I meant to say!!
TCAS is a useful tool in helping with the situational awareness, if used correctly, as you said.
Alexban
UK forces are no longer allowed to 'embellish' civil A/C. I don't know about overseas
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Originally Posted by anotherthing
Captain Pit Bull,
In the vertical sense, it can help the situational awareness, but in a horizontal sense ACAS/TCAS is very unreliable in azimuth. It's misuse has caused incidents in the past, when A/C that were on headings to miss each other by 5 or more miles have actually had an airprox because one of the sets of crew decided to turn the A/C on the strength of the information they saw on the display.
In the vertical sense, it can help the situational awareness, but in a horizontal sense ACAS/TCAS is very unreliable in azimuth. It's misuse has caused incidents in the past, when A/C that were on headings to miss each other by 5 or more miles have actually had an airprox because one of the sets of crew decided to turn the A/C on the strength of the information they saw on the display.
It is perhaps weakest used as as an SA tool in the vertical sense, because some manufacturers and operators set the display parameters very low, typically own altitude +/- 2600ft.
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Kit,
Huh? That quote you've made isn't from me.
Having said that, whilst I agree that it can be quite reasonable in azimuth, it isn't for all circumstances (this has been discussed several times here and on tech log over the years).
The main issue IMHO is not so much the accuracy of the traffic the display is showing you, but rather being aware that there may well be traffic the display simply isn't showing you at all: - non transponding aircraft, interference limiting mode, suppression of other traffic during RAs, ultimately even limits of graphical symbology.
Regardless, there have been some real howlers and near howlers caused by misuse of the Traffic Display. In particular collision courses established by flight crew making up their own avoidance manoeuvres based on their interpretation of the TD.
PB
I can't agree with your statement Captain PB
Having said that, whilst I agree that it can be quite reasonable in azimuth, it isn't for all circumstances (this has been discussed several times here and on tech log over the years).
The main issue IMHO is not so much the accuracy of the traffic the display is showing you, but rather being aware that there may well be traffic the display simply isn't showing you at all: - non transponding aircraft, interference limiting mode, suppression of other traffic during RAs, ultimately even limits of graphical symbology.
Regardless, there have been some real howlers and near howlers caused by misuse of the Traffic Display. In particular collision courses established by flight crew making up their own avoidance manoeuvres based on their interpretation of the TD.
PB
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how sure are we it was an RA at all? my understanding of the system is that a relative old fighter jet like the RF-4E will not have an encoding altitude transponder (mode C), just a military mode 3 that implies just a symbol and a "trafic, trafic" in the 737....
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Originally Posted by Aristomenis
They play well all right, 24 hours a day, 365 days a year, keeping your (singular) country's airspace free so that you can fly your NG with safety...
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TCAS issue
Hi everone!
Eurocontrol released a pretty good article about the misuse of TCAS and the consequences.
If you have a look at the section 'moving reference display', you will also see that optical 'illusions' can lead to incorrect interpretation of the displayed traffic.
The article finally tries to say that TCAS is not a radar replacement, but more an assisting system and guide!!
If you like, see the article here:
http://www.eurocontrol.int/msa/galle..._21Apr2005.pdf
Eurocontrol released a pretty good article about the misuse of TCAS and the consequences.
If you have a look at the section 'moving reference display', you will also see that optical 'illusions' can lead to incorrect interpretation of the displayed traffic.
The article finally tries to say that TCAS is not a radar replacement, but more an assisting system and guide!!
If you like, see the article here:
http://www.eurocontrol.int/msa/galle..._21Apr2005.pdf
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Originally Posted by OXOGEKAS340
keeping it free from.....what?
so this is pretty intereresting.Join Date: Sep 2003
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Just curious, does the RA specify a speed/rate of descent, or is there a standard?
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Originally Posted by Aristomenis
Well, I suppose you have found the BIG solution for a great aviation future.... Since you find no meaning in their existence, we should seize every country's air force...
It is a reason, to spend thousands of millions of
euros, every year! And as far as I know, at the same position, I filled 3 times AIRMISS, a few years ago.......trying to escape from the rushing towards us, F5's!
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Cloudcruiser,
TCAS II gives CLIMB or DESCENT RAs which basically call for a change of pitch attitude within 5 seconds which will achieve 1500 fpm ROC/ROD when stabilised. The pitch change depends on your TAS and can be calculated by (pitch change = 1000/TAS). For most civil jet transports this gives a range of approx 2.5 - 7 degrees pitch change. An INCREASE CLIMB or INCREASE DESCENT RA calls for a further similar pitch change within 2.5 seconds to achieve 2500 fpm. INCREASE RAs usually occur only when one a/c does not respond within the above parameters or is non-TCAS.
Most TCAS problems are pilot induced by under-reacting or, more frequently, over-reacting in pitch and 'zooming' into someone elses airspace. Pilots should always be aware of their TAS so that they can get their initial response correct. TCAS will give corrections if you get it wrong, but not all systems have 'damped' IVSIs.
Incidentally, don't be confused by some previous posts. TCAS II IS NOT RELIABLE IN AZIMUTH. Having used it and trained pilots in its use for several years it usually appears to be so, but manoeouvre based on TCAS display alone is outside the design parameters of TCAS II and expressly discouraged by the manufacturers.
rts
TCAS II gives CLIMB or DESCENT RAs which basically call for a change of pitch attitude within 5 seconds which will achieve 1500 fpm ROC/ROD when stabilised. The pitch change depends on your TAS and can be calculated by (pitch change = 1000/TAS). For most civil jet transports this gives a range of approx 2.5 - 7 degrees pitch change. An INCREASE CLIMB or INCREASE DESCENT RA calls for a further similar pitch change within 2.5 seconds to achieve 2500 fpm. INCREASE RAs usually occur only when one a/c does not respond within the above parameters or is non-TCAS.
Most TCAS problems are pilot induced by under-reacting or, more frequently, over-reacting in pitch and 'zooming' into someone elses airspace. Pilots should always be aware of their TAS so that they can get their initial response correct. TCAS will give corrections if you get it wrong, but not all systems have 'damped' IVSIs.
Incidentally, don't be confused by some previous posts. TCAS II IS NOT RELIABLE IN AZIMUTH. Having used it and trained pilots in its use for several years it usually appears to be so, but manoeouvre based on TCAS display alone is outside the design parameters of TCAS II and expressly discouraged by the manufacturers.
rts
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Originally Posted by rodthesod
TCAS II IS NOT RELIABLE IN AZIMUTH. Having used it and trained pilots in its use for several years it usually appears to be so, but manoeouvre based on TCAS display alone is outside the design parameters of TCAS II and expressly discouraged by the manufacturers.
Originally Posted by Kit d'Rection KG
I have never seen a TCAS target which couldn't be confirmed in both range and azimuth using airborne radar (...)
It is perhaps weakest used as as an SA tool in the vertical sense, because some manufacturers and operators set the display parameters very low, typically own altitude +/- 2600ft.
It is perhaps weakest used as as an SA tool in the vertical sense, because some manufacturers and operators set the display parameters very low, typically own altitude +/- 2600ft.
B737 climbed 1000 ft within 2 seconds.
That would mean, they arrested the descent and climbed 1000ft within
2 seconds.
Now if you calculate that, you end up with a climbrate in excess of 30000 fpm.
How realistic is that, and what would be the g-forces implied?
That would mean, they arrested the descent and climbed 1000ft within
2 seconds.
Now if you calculate that, you end up with a climbrate in excess of 30000 fpm.
How realistic is that, and what would be the g-forces implied?
To climb 300m in 2 secs, one needs average vertical velocity of 150m/s. Let's assume acceleration and decceleration are constant. It's oversimplification but it will give even lesser normal acceleration than peak acc required in "realistic" scenario. So in the first second of climb one needs to accelerate fom zero to 300m/s and in the second the same amount of decceleration is required. And that's pull-up of 30G, followed by -30G nose-over. That kind of normal acceleration would pulverize 737 (and pax too).
Most fighters in use today carry transponders compatible with civllian mode C. A colleague of mine was once practice intercepted by pair of Armee de l'air Mirage 2000C's. First ATC asked them if they agreed to be intercepted. After they agreed, soon they got TCAS targets on ND and ATCo warned them that fighters will soon turn off their xpndrs to avoid triggering RAs. Mirages did that at about 6 Nm distance and turned them back on after disengaging.
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A question about the future here, guys, sorry to interrupt. Does anyone know whether the promised ADS-B/TCAS hybrid systems will improve this azimuth inaccuracy issue? And accuracy of TCAS generally? Grateful for some info-I'm doing some research on the issue.
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TCAS IV
Wrongthong,
The azimuth 'issue' is only an issue when pilots try to do what they're expressly advised not to; i.e. manoeuvre in azimuth by interpreting the TCAS II display. TCAS II does not require to know where the other a/c is, only its altitude, distance from your aircraft and rate of change of that distance.
There will be no TCAS III.
My understanding is that TCAS IV will incorporate an air-to-air data link of the aircraft GPS position, so enabling much greater accuracy of azimuth presentation.
I'm a bit out of touch, having retired from flying 2 years ago, but I'm sure Collins or Honeywell would be happy to assist with your research.
rts
The azimuth 'issue' is only an issue when pilots try to do what they're expressly advised not to; i.e. manoeuvre in azimuth by interpreting the TCAS II display. TCAS II does not require to know where the other a/c is, only its altitude, distance from your aircraft and rate of change of that distance.
There will be no TCAS III.
My understanding is that TCAS IV will incorporate an air-to-air data link of the aircraft GPS position, so enabling much greater accuracy of azimuth presentation.
I'm a bit out of touch, having retired from flying 2 years ago, but I'm sure Collins or Honeywell would be happy to assist with your research.
rts
The TCAS system is never going to be particularly accurate in azimuth due to the design of the antenna's. The TCAS antenna is in fact four in one, one antenna per quadrant, the TCAS computer sees which quadrant the signal is received in most strongly, then compares this with the strength of the signal received in an adjacent quadrant and "guesstimates" the bearing of the other aircraft.
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Can someone please clarify the following:
ACAS/TCAS systems fitted to commercial aircraft work on either modes A, C or S and only an "s to s" contact will trigger the full cockpit TCAS aural and visual alerts.
Military aircraft typically operate a IFF (friend or foe) system, so when switched on, this system has therefore to be mode S to issue alerts to commercial aircraft.
Are all military aircraft Mode S equipped then?
Evvy
ACAS/TCAS systems fitted to commercial aircraft work on either modes A, C or S and only an "s to s" contact will trigger the full cockpit TCAS aural and visual alerts.
Military aircraft typically operate a IFF (friend or foe) system, so when switched on, this system has therefore to be mode S to issue alerts to commercial aircraft.
Are all military aircraft Mode S equipped then?
Evvy