TCAS II Range Selection

[jpslabau]

I am in the middle of a “discussion” within our flight department. The subject: TCAS II range selection technique. Our Chief Pilot insists on selecting the lowest range (6nm) upon descending through FL180. He put it on our checklist. It is mandatory within our company. His research has convinced him that this display range is the best one to aid in spotting traffic. The FAA recommends a range of 10nm or less below 10,000. The AFM says 6-12nm range is optimal below 10,000. While I agree with this, I think a 12nm range from FL180 to 10,000 provides a better picture of what's coming.

I would like to hear opinions and techniques from other operators. How do you operate your TCAS range?

We operate a Citation Excel, Part 91.

Thanks.

[ahramin]

TCAS should always be set to the longest range that is useable. When the display gets cluttered or you want better information on a particular target, then bring the range down.

If you are descending in your excel at 350 knots, and a turboprop is chugging the other way at 200 knots, you have less than 40 seconds to close 6 miles. With closure rates of close to 1000 knots common you can have less than 30 seconds from the time the target shows on your screen until you converge with it. With TCAS II you could get the RA before the target even shows up.

[ssg]

I hate to say it...

At the risk of pissing him off..give him this example..

Your coming out of 180, TCAS set at 6nm, traffic ahead at 20 nm...ATC says follow the traffic at 12 oclock for the visual ...how do you do that? With your super Xray vision?

Your coming out of 180, your high, traffic is in the pattern, on approaches, about 50 miles ahead...having your TCAS on 40nm will help you see them early..

And the last...if I am doing .76 in a Citation(430 kts) coming out of FL180, 6nm traffic will be on top of me really quick, expect TAs, hard banks, ect when that traffic could have been seen and easily managed much earlier.

And the very last...if there is a ton of VFR traffic around, flying at 12000 feet, your doing .76, don't you want to see them early?

My quess...if your chief pilot wants you at 6nm on the TCAS so that your already setup for the terminal area and not fiddling with the buttons on the ILS..

Am I right?

I agree with the previous...set to longest range, that is manageable...too much traffic out there, set it to manage the closest threats...since the amount of traffic can't be predicted, the idea of preset on the checklist doesn't take varying traffic density into account.

[jpslabau]

My quess...if your chief pilot wants you at 6nm on the TCAS so that your already setup for the terminal area and not fiddling with the buttons on the ILS..

Am I right?

Correct. After the FL180 check, the next item on the checklist is the approach check, which doesn't work because the TCAS range should be toggled down to a lower range prior to that.

By the way, I gave him the speed/time argument. He didn't care. He says that 30 seconds is all the time you need to "see" potential threats.

I know it sounds dumb to argue over something so petty, but the debate has been going on for years.

I appreciate your opinions.

[ssg]

I figured as much...

He's micromanaging you....any number of reasons for this..

Are you low time?

[CJ Driver]

As you (and your chief pilot) are probably aware, the range only changes the picture displayed on your screen - it doesn't change the behaviour of the TCAS system itself, so you will still get RA's for traffic whether you see it on the screen or not. Adjusting the display scale just makes it easier (or harder) to use the screen to find "visual" traffic.

[EatMyShorts!]

How can you make the setting of your TCAS-range *mandatory*? This is unsafe, TCAS should be used to its best and if you need a higher range, then use a higher range. I used to fly XL and depending on the speed and type of airspace a higher or lower range is needed. If somebody put _this_ into my checklist, I would try to follow it. But when I needed a higher range, I'd use a higher range. Best use of equipment!

[Capt Pit Bull]

Your coming out of 180, TCAS set at 6nm, traffic ahead at 20 nm...ATC says follow the traffic at 12 oclock for the visual ...how do you do that? With your super Xray vision?

No... if you can't see it, you can't see it. How can you take responsibility for visual separation against something you can't see? All you can say is 'not visual with the traffic' or words to that effect.

Sounds to me like over use of the traffic display. Its purpose is to give you a chance to get eyes on the threat during a TA.

If you're relying on for arranging your own separation, you're cruising for a brusing. Its neither designed nor certified on that basis. There's too many things that can cause traffic not to be displayed. There have been a number of serious incidents caused by pilots misusing the traffic display. Cranking out the range in the expectation thats you are getting some sort of 'Gods Eye' view is wishful thinking sadly. This is especially true in high traffic densities.

Not withstanding that, back to the OP. I don't think mandating a range setting is wise. A pointless loss of flexibility. However, if I *was* going to mandate something, I'd choose 6 miles rather than 12. You can not judge if you are on a collision course with a blip, a turn is just as likely to cause a conflict as solve it. Short range so you can get your eyes on the conflict is the way forwards. Don't forget, you'll still get 'off scale' blips on the edge of the display for TAs and RAs even if you do get a high rate of closure incident.

Just a thought, maybe he wants your eyes looking out the window rather than looking at blips on a tiny screen?

Personally, I wouldn't mandate and particular display settings, though I'd certainly recommend a short range.

pb

(TCAS instructor in a former life)

[ExcelXLS Driver]

Hi Jpslabau,

I fly the XL and XLS. I am working for a company out in Switzerland and on departure we set the TCAS as required either 6 or 12nm and ABOVE. Personally I would set 12nm depending on the amount of traffic around. 12nm gives you a better view of what’s out there and you have the option of reducing the range if needed.
With the rate of climb you can get out of the XL its better to see what’s out in front of you which is why I set 12nm. If the TCAS is clear of aircraft for 12nm then you can keep a high rate of climb without the worry of setting off a TA.

Once you are out of the TMA or pass FL100 then I would set the range according to the traffic around me. If the sky is clear then 20nm would suffice.
On our Cruise check we set 20-40nm and angle the scan DOWN. These gives us a better picture of traffic below, but with the same range forward and above the aircraft that setting NORMAL would give you.
Above FL400 where we normally cruise there is not a lot of traffic, so by setting NORMAL on the TCAS you would reduce the vertical distance scanned below the aircraft, which is where a conflicting aircraft is most likely to come from. Also when its time to descend you don't need to touch the settings until FL100 or below when the range can be set to 12 or 6nm as required.

I would suggest that you set the TCAS range to what you are most comfortable with, but keep a low range set inside or near to your departure or destination airfield or and area which has a large amount of traffic.

Hope this helps.

[ssg]

Pit Bull..

Pit Bull..

How many times has ATC told you to follow traffic that you couldn't see or find? Or how about ATC telling you that traffic is up ahead intercepting the ILS, ..he's too far out to see visualy, but not for TCAS...so you bump up the range to find that traffic if need be...

So now you have TCAS, you see the blip up head, you can put your eyes at 10:30 rather then 1 oclock, catch that traffic faster...makes things easier. I don't think TCAS is a substitute for looking outside, anymore then EFIS does a whole lot more then iron guages did...but TCAS works, most of time ,and is very, very helpfull.

For the other guy...

The point: In the real world...all traffic isn't always within 6nm away, and to assume that any traffic beyond that isn't a threat is kinda silly. If you have time, there is nothing on your screen in the 6nm mode, put it on 12nm.

I simply display as much traffic as I feel I can handle...in cruise it might be 40nm, on the ILS it's probably 6nm...depends. I simply want to manage the traffic around me...while 6nm all the time is silly...putting it on 40nm all the time is to worry about traffic way out there while you might have more credible threats up close...

The issue is your being micromanaged...something I understand...

I was just offered a job where the owner (pilot) looking for a chief pilot told me where to maintain the plane, what mechanic to ask for, where to go to school, what facility, what charts to use, and how to set up the plane, buttons, ect for him after I flew, so he had everything ready for him.

Not generaly a problem, but all his decisions were just wrong...and it would have been a headache educating him...

He was looking for a pilot...not a chief pilot....No one will work for this guy..only the contract guys, because they don't have to listen to him...

I didn't accept the position, based on one very simple premise, if during the interview process he's going to get that picky, can you imagine how much of a control freak the guy will be with all the others items not discussed.

Sorry but I don't work with SOPS manuals, or inflexible people that think everything that can happen is on the checklist, because it's not.

They either respect your judgement or they don't. Very simple.

If you need the job fine, but working for a guy who's telling me where to set the TCAS range is just a headache...and an argument in the hangar...