Loss of seperation????

[MMENCLLBAMAN]

Hi,

My first post after a long time reading (and hopefully learning)

I work for a tour operator as a hotel contractor and fly regularly.

I am curious, flying back CGN-MAN this afternoon with HLX and something really unnerved me - flying in proximity to London (according to broadcast map), looking out of the window and enjoying a beer I saw another aircraft what looked like coming straight for us at same FL.
It kept coming to the point I seriously thought we were going to colide - I swear I could see the crew in the flight deck at the last moment.At what seemed like the last secoond we desended very, very quickly and went into a very steep left turn (much steeper than I have ever experienced after well over 3-400 flights) There was a noticeable increase in engine noise.
As we came out of the bank I could see the other aircraft above us at what must have been very close (was not a livery I recognised).

Purser was called to the cockpit afterwards but no announcement was made. However it seemed to me like a very near miss in UK airspace.

I could (and hope I am) wrong - please do not blast me for this, it really shook me and some of my fellow passengers up. Lets just say the crew made a few extra pounds of comission from whisky sales.

If anyone could shed any light I would be very happy,

Thanks guys - most of you do a pretty remarkable job keeping us SLF (and yourselves) safe.

Chris

[danishdynamite]

Can you please specify the date of the flight?

[MMENCLLBAMAN]

Yesterday 1st June - 1925 flight CGN-MAN

Txs

[TheGorrilla]

Sounds like the crew may have responded to a TCAS RA.

[Tarq57]

Sounds like the crew may have responded to a TCAS RA.

The description does fit that, but a bit unusual that the engine noise increased during the descent. Sure it wasn't spoiler noise? Or did the engines power up after the descent was finished?

[Not to scale]

Would a TCAS RA involve anything other than a climb or descent?

A steep banking turn as well??

[jackbauer]

Definitely not, TCAS only directs you to climb or desend. Turning can only compound your problem. While you are climbing the other aircraft is directed to do the opposite. This assumes both aircraft are fitted with TCAS. Very clever system!

[NigelOnDraft]

Would a TCAS RA involve anything other than a climb or descent?
A steep banking turn as well??Aeroplanes do have windows, and pilots do have eyes :rolleyes:

[jackbauer]

Sorry Nigel but the first rule of TCAS procedure is NOT to maneuver based on TA alone. You must wait for the RA to trigger before you do anything. Relying on visual contact to avoid is not recommended as you can easily find yourself in a secondary RA and deep doo doo! It's getting to a point where we only need the windows for the last 50 feet of the approach, and even that's optional.

[Jerricho]

IF (big IF) it was a nasty, perhaps the turn was avoiding action issued by ATC?

Question from me - I'm led to believe that it's SOP for some operators out there if a an RA is received whilst in a turn some will stop the turn/adopt a more wings level attitude.

[jackbauer]

You NEVER EVER give priority to ATC over a TCAS RA!! Do I have to tell you about the Ueberlingen incident? You follow TCAS with wings level. This is a memory item guys, why are so many people asking if it's OK to do anything else? If you are flying in busy airspace with the idea you can do your own thing, it is very worrying.

[Citation500]

Well, Jack of course you are absolutely right, but I think Jerricho ment the crew probably followed an ATC command, BEFORE the RA kicked in.

[bomarc]

citation 500 is quite right. as to engine noise increasing, the passenger reported that the bank was very steep...perhaps the pilots were making darn sure they kept a safe speed .

I do think the passenger should take some solice in knowing that everything did work out. a miss is as good as a mile or should I say three miles.

[sudden Winds]

the turn could have been initiated after someone in the cockpit saw the intruder a/c, basically the PF follows the RA commands while the PM tries to spot the traffic and calls out any ommitted actions, then inform ATC.
The "engine noise" could have been the sound of the airflow increasing, and not the engines themselves. If description is right chances are it was an RA.
Regards,
SW.

[Jagohu]

The turn could have been given by ATC when they realised you're gonna get too close to the other a/c. Since we're also taught not to give vertical clearances if TCAS is involved, and we all know that vectoring is a much better idea than trying to push a climb/descent, the controller could have given an avoiding turn, to increase separation if this was the case.
Anyway, not that much, but still better to end up with 3 nm and a TCAS RA than with 0 nm and a TCAS RA...

[Basil]

<<the first rule of TCAS procedure is NOT to maneuver based on TA alone>>
Must say that I HAVE done so.
Level 330 in heavy classic.
Crossing traffic cleared climb 320 continues climb past 320.
I guessed they'd mistaken 320 for 330 and started climb.
ATC then told us to climb.
My reasoning was that, if his performance was greater than ours we were better to start climb sooner rather than later.
Command decision on the day :ok:

[MMENCLLBAMAN]

Thanks for the info guys - appreciate it.

As for the engine noise - I have to admit that I think 'and overall increase of noise' would have been more appopriate to say - I have to say that I assumed rather than was sure.

And bomarc, believe me I was full of solice :O

Can anyone tell me how regular these type of instances are??

Safe flying

Chris

[Jerricho]

Thank you Citation500 :ok:, that's exactly what I meant. Avoiding action given by ATC then RA. Seen it happen.

As to regularity, in high density airspace RA can be triggered by high rates of climb/descent of closing traffic before they level off. As TCAS is timed based, the system ascertains a "closest point of approach" of the traffic and provides a resolution if required.........not knowing the other aircraft will be levelling off.

[Rainboe]

Before we get this done and dusted as a TCAS Loss of Separation incident and it goes down in the PPrune record as that, perhaps someone could confirm whether there has actually been an airprox incident in the London area on 1 June, or is this an overactive passenger impression?

[MMENCLLBAMAN]

Rainboe, I truly hope that indeed that was the case - but still this overactive passenger was less than impressed :uhoh:

[Jagohu]

I don't think any of the controllers are authorised to say anything about these things... I know about ppl who got into trouble for saying something like that here on pprune...

[captainlj]

MMENCLLBAMAN sounds like he's either a passenger with an over active mind or a journalist on the sniff for a future made up feature in the 'Red Tops'.

:bored:

[NigelOnDraft]

jackbauerSorry Nigel but the first rule of TCAS procedure is NOT to maneuver based on TA alone. You must wait for the RA to trigger before you do anythingWho said anything about a TA and/or RA :ugh:
TCAS is a vertical aviodance tool only, as discussed above. I know of no reason or rule not to use lateral avoidance as well if I do not compromise the vertical avoidance. If, and it's a big if, the event was as dramatic as described, then the TCAS "system" had either failed, either the equipment or one or more crews. You are a better man than I if you are going to fly into another aircraft you see and tell your maker "but TCAS said nothing" :{
As you say, "do not manoeuvre based on TA alone". I would agree... However, a TA action (for us anyway) is to "attempt to see the reported traffic". What is the point of attempting to see the reported traffic if the subsequent drill is to fly into it :( A TA and/or visual sighting is not "TA alone".
So I am afraid my principles stick. TCAS is a vertical only mode, and judging / achieving vertical seperations is difficult - so let TCAS look after that. TCAS does not look after you laterally, and visually judging / achieving lateral separation is easier. If I felt genuinely threathened by traffic acquired visually, and TCAS appeared incorrect or silent, I would certainly take lateral avoiding action.
On your principle, with the Legacy v 737 midair, you are saying that if either crew saw each other, they should have just folded their arms and waited to die :{

[TheGorrilla]

Indeed chaps, TCAS 2 is vertical gudance only. Best complied with because the information is up to date within milliseconds as opposed to atc instructions. However, the first thing we are told to do in the event fo a TA in VMC is to LOOK for the other aircraft. If spotted all future commands may be disregarded at the pilots discretion.

However, arguing against a TCAS 2 RA in the office or in court afterwards is going to need some real solid justification. Unless the TCAS 2 unit was confirmed to be playing up.

That said, who's to say MMENCLLBAMAN didn't experience one of aviations popular visual illusions.

[barit1]

This (http://www.ntsb.gov/ntsb/brief.asp?ev_id=78645&key=0) was an apparent near-miss in 1965.

Of note: Eerie precursor (interaction between two aircraft, in the same locale) to AA587 (http://www.ntsb.gov/ntsb/brief.asp?ev_id=20011130X02321&key=1).

[VectorLine]

I swear I could see the crew in the flight deck at the last moment.

What a load of bo11ocks and you lot have been sucked right in.

[bracebrace!]

I agree with VectorLine

Don't feed the troll.... :=

[Basil]

For info to passengers.
Vertical separation in the approach phase is 1000ft.
When banked over in a turn, e.g. whilst holding, you may find yourself looking down or up at a B747 which is only 1000ft away and the illusion is created that the separation is lateral when, in fact, it is vertical.
Looks a lot more punchy than it really is.

[Itswindyout]

TCAS dos not take into account the aircraft weight, or config, so as Basil in post #16 stated TCAC will generate the resolution of climb, but the aircraft might just be unable to climb, then the secondry warning DO not climb, puts both aircraft at risk. As the time delay in "ignoring" the initial instruction.

It should be able to modify the AP FMS to initiate the climb, or descent. After all I can do an emergency descent fully automatically, if depressurised.

Lastly are there any modern aircraft that has the ability to feed SE situations to the TCAS, or must the RA be inhibited.


Its windy out

[5milesbaby]

Just trying to picture this and its not adding up. You'll need to correct me if I'm wrong but assumed that you were flying Cologne to Manchester on Hapag LLoyd Express as I only work in ICAO. You have to bear in mind that around London at all levels there are lots of converging routes, and 1000ft separation used at all levels, which I know looks seriously close and can worry those not used to seeing it. I'm guessing you're looking out of the RHS and seeing traffic coming toward you at between 45 and 135 degree plane, you can't see much more than 45 degs out of a window. Near London you will still be in the cruise so at the speeds you'll be travelling if you "saw the crew in the flightdeck" then I'd expect you to be dead now. TCAS would have activated over half a mile away if it actually did. With all the "knitting" that goes on in the London Upper Sector I suggest you were given a turn and descent at the same time for streaming into Manchester with a speed restriction too hence all the noise, and the turn with descent will just compound the feeling of a high velocity manouvre. I'd say the presence of an aircraft in safe close proximity was just the luck of timing.

Please correct my initial guesswork if I'm wrong and I'll try to think of any other non-life threatening possibilities as there are several more that can explain what happenned.

[Final 3 Greens]

I'm FQTV SLF with PPL.

Sitting in 1A last week, enjoying view out of the window in the cruise when a jet at slightly lower level went past at 90 degrees like a bat out of hell.

I'm sure that it was 1 or 2,000 (or more) feet below, but the unexpected appearance and the relative speed could well shock anyone who travels infrequently and is not used to such events.

I wonder how many reported near misses are as a result of this... no inplication intended to the first poster on this thread.

[RoyHudd]

Lots! They look kinda close to us sometimes, even though we know full well from TCAS that there is 1000 separation. Good call, F3G

[begbie]

Last year was on a shuttle down the hill from Glasgow to Heathrow. Around the Manchester area a Shamrock passed underneath at 90degrees to us. Was standard separation but at the speed it happens, 1000 feet doesn't look like much! Was interesting to see the perspective from the air after spending all these hours watching it on radar!

[Irish Steve]

Two comments.

A very long time ago, pre TCAS, on the jump seat of a 737, we were given a warning 'opposite direction traffic 12 miles 1000 Ft above you, so we all of us looked out to see if we could see it. For a very short period of time, we did see it, and we were very happy that ATC had confirmed the separation, as it went past us directly above us. The entire event ( it wasn't an incident, so I'm being careful here) was over in less than 30 seconds, given the cruise closing speeds, but it was discussed in some detail for a lot longer than 30 seconds.

Another very long time ago, due to a LGW controller suppressing the Dunsfold transponder returns, a DAN AIR 1-11 positioning from Lasham back to LGW after maintenance was put at the bottom of the TMA, effectively at 2500 Ft. At the time, we were also over Dunsfold at 2400 Ft, just below the base of the TMA. I can assure you, as we were standing my twin Com on a wing tip, we DID see the crew members in the 1-11 as they turned left for the continued approach to LGW. I never did find out if the 1-11 crew saw us, the controller at Lasham was considerably less than happy, as he was giving us a RAS at the time, and due to late detection was only able to give us about 20 seconds warning of 'opposite direction traffic at or close to your level'.

The controller filed an airmiss, and that's how we found out that LGW has supresses the Lasham transponder returns and therefore didn't see us on their scope.

Close encounters do happen.

The event in this thread might not have been as close as we first thought, or it could have been a full blown TCAS event, bear in mind that depending on the closing angle, the flight deck might not have even seen it until they got a TCAS alert, it it was closing from behind, it would have been very visible from the cabin, but not from the sharp end!

[slip and turn]

1000 feet planned vertical separation can look very close indeed, especially in a turn. However, as alluded to by Basil earlier, co-ordination and maintenance of separation during potentially conflicting climbs and descents is surely where the greatest risk lies. There is a lot of that going on around London at any given moment!

[NW1]

However, the first thing we are told to do in the event fo a TA in VMC is to LOOK for the other aircraft. If spotted all future commands may be disregarded at the pilots discretion
No longer the recommendation. Check here (http://www.arinc.com/downloads/tcas/ACASII%20Bulletin%20Colour%20JULY.pdf) under "Visual acquisition - Limitations" and the Conclusion.
Bottom line - follow the RA, no exceptions.