Bae Hawk Tcas

[Lear45XR]

Hi all,

While flying along at FL320 a crew got a TCAS RA because a Hawk was climbing at over 6000fpm right under them. The Hawk was cleared to FL300. Is the Hawk equiped with TCAS or similar technology?

Thanks!

[Ivor Fynn]

No - just a transponder that a TCAS equipped aircraft will pick up.

Ivor

[Lear45XR]

Thank you!

[Dengue_Dude]

A couple of years ago I was working on some stuff for BAe Hawk and the newest variants are being fitted with TCAS which is ported to one of the MFDs.

I informally discussed with the design team the effect of a Hawk climbing at high VS rates whilst crossing or operating within controlled airspace and warned of the potential 'bomb burst' effect of that on 'normal' airways traffic.

THEY understood then the implications, I have no idea if the info was passed on. I was the only guy on site that had actually operated TCAS!

[Ogre]

I probably shouldn't, but I can confirm that they are doing some serious work on TCAS for the latest Hawk.:ok: A lot of time has been spent on the algorithms and going through the flight trials for certification.

[beardy]

Ivor,

Read carefully, the Hawk generated an RA in the 320. Hence the Hawk had TCAS fitted.

[BEagle]

Nope, beardy, the Hawk wouldn't need to be TCAS equipped to generate a RA!

RAs can be generated from a normal Mode C SSR climb rate; however, co-ordinated RAs can only be generated through the Mode S data link if both aircraft are fitted with TCAS II.

[beardy]

BEagle,

You are, of course, correct. TCAS II does cater for previous generations of IFF with height reporting. Aplogies Ivor.:O

[Ivor Fynn]

Thank You Beags:E:E:E

[BEagle]

A good 'ground CAT' question, perhaps?

Incidentally, AIC 107/2007 (Yellow 252) gives a good summary of the UK sitch regarding climb and descent rates in CAS. If you are registered on the appropriate website, you can download it from http://www.nats-uk.ead-it.com/aip/current/aic/yellow/EG_Circ_2007_Y_107_en.pdf .

If the Hawk was in UK CAS and cleared to FL300, it should have been reducing its climb rate to 1500ft/min or less from FL285 onwards. Easy way to remember is 1000/1000 - a vertical rate of no more than 1000 ft/min within 1000 ft of the cleared altitude or level.

Oh to still fly something which can climb at 1500 ft/min, let alone 6000 ft/min!

[Naskopi]

Hawk 128 does have TCAS, it does work, Tx and Rx. There are now several beetling around the skies.

[Capt Pit Bull]

Something to bear in mind though is that the guidance as to what rates to fly within the last 1,000 feet seems to be based on the idea that the rate previous to that was a more typical C.A.T. value.

But if you're doing 6000 fpm, with an RA time of 35 seconds, you'll be predicted inside the RA vertical envelopes whilst you are perhaps 3,000 feet to go. (back of an envelope approximation 6000 fpm for 35 seconds = 3,500 feet, predicting a 500 foot overshoot when you are 3000 to go puts you in RA territory).

If aeroplanes that are routinely operated at 6000 fpm (or higher) are going to be TCAS equipped then that rule of thumb isn't adequate.

Without wishing to cast any aspersion, I hope the pilots of such aircraft know what they are doing in regards to TCAS operations. If high pitch rates are underway when an RA is issued then the likelihood of reversals being issued and general mayhem ensuing is pretty worrying. The TCAS manouevres are not based around the sorts of pitch rates that fast jets can generate.

pb