Descend through your level....

[Max FlightTime]

A technical question..
If I am level at FL230 on an airway in a secondary radar environment what is the minimum distance in front of me that ATC can clear opposite direction traffic to descend through my level?

[160to4DME]

Depends if you're IMC and non-TCAS equipped :)

[zonoma]

All depends if your on a radar heading or not. On headings, we just have to get 5 miles laterally, on your own nav, we have to ensure safe vertical seperation when 5 miles is broken. Obviously trying to get 5 miles and 1000/2000ft exactly is pure dangerous, we are taught to use our initiative. Closing speed plays a big part in this. Why do you ask, you got a bit too close for comfort or something??

[Loki]

Zonoma

I sort of agree, but I have managed the exact minimum on many occasions. However, I have always followed the advice "if you are going to cut it fine, go behind"

[Spuds McKenzie]

You're a very brave man, Loki!
Seriously, going for the minimum is Russian Roulette. Head on with climb through: To be avoided, unless it's not busy and you can monitor and/or separation will be established early enough (depends on speeds as well), plus give ROD/ROC instruction.

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"say again?"
"again"

[Rad1]

Surely the answer is that you have to get the relevant radar separation - but I agree that going for the minimum is asking for trouble, even if it's worked 'till now, it'll go wrong one day!

[Max FlightTime]

Sorry - I'll clarify the situation. TCAS equipped, on an Airway approaching a VOR (<10 miles) doing 400+ TAS. Opposite traffic descending in about 1 o,clock position.
Secondary radar environment but neither traffic being vectored.
Answers please.....

[Spuds McKenzie]

Good Question.
Looks like you were lucky.....

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"say again?"
"again"

[Take 5]

RAD1

You should ENSURE 5 miles radar separation, not just get it !!

The answer is a bit like "how long is a piece of string" but in an en-route environment at cruising jet speeds, a trainee would be bollocked for doing anything opposite direction without headings to ENSURE 5nm separation if the a/c were within 50nm of each other, as a guide.
Crossing tracks would reduce this to about 20nm.

[Max FlightTime]

About 400+ people were very lucky...
I am not going to give enough detail to allow the parties to be identified due to the public nature of PPrune. An MOR has been filed and the ATC unit (foreign but EU) will doubtless respond in due course. We had a TCAS "Traffic" warning with the target at about 5nm descending through 1500 above us. Expected him to stop at +1000 but he kept coming so prior to the inevitable RA we took avoiding action. An RA occurred during the avoiding action.
At the time the ATC frequency was extremely busy - both before, during and after.
Does not ICAO specify a minimum opposite direction distance for traffic to cross your level even when in a secondary radar environment?


[This message has been edited by Max FlightTime (edited 11 May 2001).]

[This message has been edited by Max FlightTime (edited 11 May 2001).]

[ferris]

All,
before jumping to conclusions, a VOR was mentioned. Maybe a/c outbound VOR had left area of conflict, therefor no conflict? Just a thought, as I have been quizzed about 1NM sep achieved by this method. Pilots didn't like it but perfectly legal.

[fweeeeep]

Hang on,

5nm
FL230
Head on
and still wrong side of seperation (kept on comming down)
..........ouch !!
1 of 2 events, Pilot or ATC error.

As a matter of interest did your resolution advisory send you furthar in the direction that you had already chosen to avoid ?

Glad you and yours are still with us !

[karrank]

Overheard.

"ABC, commenced descent."

"ABC, Smalltown, No Traffic."

"Oh yeah? What about the Baron I can see."

"ABC, you've passed him."

"Hey lady, I'm flying a Duke, and it doesn't have back windows."

No response....

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"Station calling Centre, grow a head..."

[Rad1]

Hey Take 5,


The question was what is the required separation in particular circumstances - the answer to such a question is, you have to get X miles or whatever (and always get it).


If I'm training someone we'll certainly talk about how to (or, if you want, ensure)
always get it.


But thanks for the tip anyway!

[This message has been edited by Rad1 (edited 12 May 2001).]

[atc_ring]

...I must agree with fweeep,
near the VOR, not on a rdr. heading and 5 miles opposite?
....definitely a dangerous error!

I always say to my en-route OJT newbees to establish vertical on opposites before 20+ N.M. from each other (unless they are vectored)...

Take care.

[APP Radar]

Every portion of airspace has a minimum lateral or vertical separation. When you lose one you must already have the other. If 5NM / 1000ft apply, when vertical separation is lost you must already have 5NM or when lateral separation is less than 5NM you must have at least 1000ft.
During training everyone is instructed not to count with minimum separation specially with opposite traffic but sometimes it happens ... in these cases ROD/ROC and traffic information is advisable.
On radar environment, even when the aircraft is not under vectoring, lateral separation means side by side / head on / or after crossing - is 5 nm (or 10) at the same level.

APP Radar

Aircraft flying IMC and not TCAS equipped helps but ...

[Max FlightTime]

Thanks for all your input.

An interesting point that has arisen from all this is the action a pilot should take when a TRAFFIC alert is obviously going to become very soon an RA. Our ops manual says do nothing and wait for the RA and obviously in most cases an RA does not result. However in this case we both felt that a serious conflict was about to arise and I commenced avoidance before the RA. Its a brave man who sits on his hands waiting for the system to tell him what is obviously going to happen...
(what if the system fails?)