Possible AirProx Incident What should I do ?
 

O.K. so I am flying along the 160 radial from LAM to the QE2 bridge en-route from North Weald to Biggin Hill in my C175 at 2200ft on the QNH.. .. .I am probably 4 miles North West of the bridge when all of a sudden the underside of a large white aircraft appears in the top of my screen having overtaken me from above and behind and I am looking at the back of this thing (probably with my mouth open and several unprintable words comming out) wondering if there is any point in trying to do anything seeing as it is now at least a mile away on what looked like a heading of 180.. .. .My passenger (a PPL with a few hundred hours) tells me (after issuing some of his own private words)to keep steady and try to hold everything straight because we are probably going to experience some wake vortex.. .. .The other aircraft crosses the Thames and banks right for what I guess is an approach to London City. My passeneger says he could clearly read the name of the airline along the side of the other aircraft as it passed us, and that it was a Dornier. . .. .It probably was not that close but it looked like 100ft! I guess it could have been much more because we did not experience any wake vortex.. .I can imagine that it may not be possible to see a small cessna in front and below because it could be below the windscreen if you are not peering out. Then again what I experienced may have been them taking avoiding action for all I know.. .. .I do know that it is not possible to see anything above and behind from a small high winged Cessna so I would never know until it were too late if something faster comes from behind.. .. .I was squawking 7000 and on the return flight I did confirm with Thames Radar that my Mode C tansponder was working correctly.. .The vis was very good.. .. .O.K. so here are my questioning thoughts.. .1. What is close ?. . How does one judge the distance accurately ?. . I am not sure how big this thing really was.. . If it was the same size as a 747 it could have been a mile away.. . If it is similar to a 146 it was close.. .. .2. What action should I take.. . Do I tell someone what it looked like from my point of view without knowing any actual facts, other than those above and the time and name on the aircraft ?. .. .3. If I am squawking 7000 does my signal get registered even if I am not working a ground radar station ?. .. .4. At what range would a small commercial airliner TCAS see my aircaft. (or would it at all ?). .. .I am not interested in assigning blame but merely in thinking about what I could and should do in any similar circumstance.. .Any ideas or thoughts would be appreciated.

I expect someone from Thames Radar will give a more detailed reply.. In the meantime, if you are concerned you should report the occurrence to the nearest ATC unit. If you are squawking 7000 we can see you irrespective of whether you are talking to us. However, your altitude reporting cannot be taken as gospel unless it has been verified by an ATC Unit, ie the controller has checked your reported altitude against what he is seeing.. .. .What altitude were you at? At what altitude would you expect the other a/c to be at, given his distance from the runway? You said you confirmed with Thames that your transponder was working on the return flight but does that mean you were not talking to them at the time of the "incident"? If you are going to fly that close to the approach path of a busy airport it would be very wise to talk to ATC. I don't have a chart to hand, but if controlled airspace was just above you then everything could be "legit".. ie you could be at the max altitude permitted outside CAS and he could be at the min altitude within. It's an unfortunate situation which exists around major airports because not enough airspace is controlled. To the west of Heathrow we frequently have light a/c bombing down the west side of our zone just a few hundred feet beneath our inbounds.. .. .TCAS will "see" your 7000 squawk but won't do anything unless it sees your altitude too.

Rough check on my chart gives the bottom of the London TMA at 2500' on that radial (up to about 50 DME). Possibly not the ideal place to be at 2200 if you're not talking to anyone - looks about 20 miles out from City, so most a/c would be at c6-7000 feet, but thats not a given.

The answer to the original question is - Report It!! The next person in your situation might not be so lucky, nor the occupants of the other aircraft, nor the hundreds on the ground underneath. Look <a href="http://www.ukab.org.uk/" target="_blank">here</a>

LRRP - Obviously a very alarming experience for you and your passenger. Only you can determine whether or not to file an AIRPROX by considering if in your opinion the incident fell within the definition.. .. .A couple of points to consider in addition to those mentioned by previous respondents.. .. .Except where aircraft are leaving controlled airspace by descent, ATC should not normally allocate a flight level or altitude to an aircraft which provides less than 500 feet vetical separation above the base of a control area or airway.. .. .This is specifically to provide some separation from aircraft operating beneath the base. Therefore in this case where the base of the London TMA is 2500 feet, the airliner should not have been below 3000 feet.. .. .Secondly, can you remember who`s QNH setting you were using. As I`m sure you know, the base of the London TMA is determined by the Heathrow QNH, although it is permissible to use the QNH of any aerodrome situated beneath the TMA as the differences are considered to be insignificant. Therefore if you were using the Biggin or Heathrow QNH then that is perfectly in order. . .. .There have, however, been incidents caused by aircraft flying close to the base of control areas using a Regional QNH even though the airspace beneath TMAs doesn`t form part of the Regional QNH system. The upshot of this has been that because a Regional QNH is a lowest forecast setting used for terrain clearance purposes aircraft have infringed the base and come close to traffic inside controlled airspace.. .. .I`m not suggesting for one moment that this is what happened but it`s just a thought.. .. .Happy flying from now on.. . . . <small>[ 27 March 2002, 17:41: Message edited by: Duke of Burgundy ]</small>

Having spent many hours in the area you are talking about, I can confirm that it is a common occurrence for traffic at the QE2 Bridge legally at 2400ft to get what looks like very close to traffic for LCY which is often crossing that part of the M25 at or descending to 3000 ft prior to intercepting the glide path for the ILS for 28 at LCY. Many is the time I have looked up at a VLM F50 and been able to see the heads in the cockpit windows as it goes overhead. An airliner of any size can look very big from 600 ft (200yds) away, especially on a nice day such as we have had recently. So provided you were on the right QNH and not above 2400ft then it was probably legal. As an ATCO I find it an anomaly that this 600 ft separation is quite legal against traffic outside CAS the intentions of which are not known, whereas we have to provide 1000ft between two aircraft inside CAS, both of which are under our CONTROL.. .. .Whilst not wishing to discourage you from making a report, I would urge you to think carefully whether the surprise by which you were taken might not be colouring your assessment of the separation between you and the Dornier (328 from Scotland, I assume!). Remember that an AIRPROX P is a situation where in the opinion of the pilot the safety of the aircraft was compromised. Was that really the case here, or were you just very surprised at how close he came while still remaining legal? If you are still convinced that your safety was compromised, then file an AIRPROX as already highlighted here.. .. .You might like to compare your experiences with those of the two pilots involved in a VERY close airmiss in the same piece of sky last year. It was recently summarised in either 'Pilot' or 'Flyer'. . .. .If you are flying ANYWHERE around the LL CTR, keep a VERY good lookout, as every b***ger is sandwiched into the airspace beween about 2000 ft and 2400 ft! <img border="0" title="" alt="[Eek!]" src="eek.gif" />

I had a somewhat similar incident a long time ago now, so it's not worth reporting as such, but it was pucker making at the time.. .. .I was flying a PA39 Twin over Midhurst VOR at 2400 Ft, doing IFR training in VFR conditions, working with full radar cover from Dunsfold, and we got a VERY late warning of possible conflict, which turned out to be an opposite direction DAN AIR 1-11 that came close enough for us to see rivets as it (fortunately for us) turned on to what was to become a downwind for Gatwick. We made an equally rapid turn away to avoid the wake!. .. .The controller at the time at Dunsfold reported the incident, and had a very "interesting" discussion with his opposite number at Gatwick, as he had been put in a very difficult position.. .. .The outcome was that the controllers at LGW were supressing all non LGW transponder returns, so we didn't appear on their screens, and they's agreed to "sneak" the 1-11 through on the base of the TMA on it's way from maintenance at (if I recall correctly) Lasham back to Gatwick, and forgotten to enable non LGW transponder returns!. .. .It was a long time ago now, but I reckon the vertical separation was about 100 Ft, and the horizontal not much more than 2 to 300 Ft.. . . . <small>[ 27 March 2002, 20:10: Message edited by: Irish Steve ]</small>

aaahhhhh Lasham.......

Thanks everyone for the feedback.. .. .I am now qute sure that the element of surprise was the main factor involved and that the safety of either aircraft was not compromised.. .There was no change of course or avoiding action, I was only aware of the other aircraft after it had already passed me so no actual danger existed by that time, I experienced no turbulence so the distance was probably further than I had thought.. .Therefore I do not think it would be legitimate to report this event.. .. .It certainly could have been much further away than it seemed and the shock of the sudden apearance from above and behind combined with the fact that I have very little experience of looking at aircraft from that perspective will no doubt have effected my perception.. .The TMA at that point is 2500 feet ie 300 feet above me and the distance involved may well have been more than 500 ft because I have no definate way to measure it.. .. .I was using the QNH given by Stapleford when I overflew their zone to pass over the LAMbourne beacon. I think I will always try to talk to Thames Radar whenever I go near that area in future. . .. .Thank you all again for helping me to clarify my thoughts on this.

HD made a very good point. When flying so close to CAS, its often worth talking to ATC (Thames Radar in this circumstance). Then, at least, ATC may have given you a warning about the other traffic.

Have to admit, I'm a little confused about what all the fuss is about here.. .. .I regularly fly at 2400' under the TMA - albeit on the other side of London (I fly out of White Waltham). I often get a FIS from Farnborough, or at least listen if I don't want a service, but I've never heard them give any traffic information about Heathrow traffic in the TMA, and neither would I expect Heathrow traffic information. The airliners sometimes look particularly close, especially when the 09 runways are in use at LHR, but I've never been concerned by them.. .. .Is this just because I did all my training at Waltham, and I'm just used to airliners being not too far above me? I remember my PPL instructor telling me once, "don't worry about the airliners - as long as they're in their airspace and you're in yours, there's nothing to worry about.". .. .FFF. .---------. . . . <small>[ 28 March 2002, 14:38: Message edited by: FlyingForFun ]</small>

FlyingForFun: Yes you are right it is probably just that I have not seen many large aircraft up close and the fact that it came from above and behind means that it just popped in to my windscreen and it was going fast means that it was unexpected.. .We have all spotted other aircraft and been surprised but this one just seemed bigger than most and because I could not see it until it had already reached the closest point it was a bit of a shock. . .. .I have jumped from many C130's in the past but in freefall the aircraft gets pretty small rather quickly.. .. .The comments made on here have helped me to think it through and put it all in to perspective. With my limited experience of 64 hours as P1 <a href="http://www.bishopsgateoffice.com/Gary/LogBook/LogBook001.asp" target="_blank">View Logbook</a> I thought I would ask for some views of more experienced people and it has helped.

Quite right to do so LRRP.. .By the way, is it correct that an Airpox has to be filed within 36 hours of the "incident" ?. .. .Cheers

AMEX - Airproxes are encompassed within the CAA Mandatory Occurence Reporting Scheme (MOR), therefore although Airprox reporting action should be taken as soon as possible following the incident, in order to comply with the requirements of the MOR Scheme, reports must be submitted within 96 hours.. . . . <small>[ 29 March 2002, 12:58: Message edited by: Duke of Burgundy ]</small>

AIRPROX is covered by (UK) AIC Pink 186, from the AIP.

The UK AIP is now available online at:

http://www.ais.org.uk/uk_aip/html/homepage.htm

Hope this helps. SC

Well done G.C. for the candid openess of your experience. Certainly helps to get things out in the open and talk about 'em......All my hard work paid off I can see!

Thanks Featherman. I think that calling D&D with a practice pan during the training you gave me helped to demonstrate that it is better to talk to someone as soon as there is any doubt.

I really think there could be more emphasis on the RT side of things to try and help new PPL pilots to feel more comfortable about asking for a service from say Thames Rader for example.

I know they do not want everyone bothering them all of the time but I now always speak to them when I am near the Thames and they do not seem to mind too much.

Does anyone know where I can find some clues as to the coverage of various Radar services and under what circumstances they should be called. Some people have also said that they never call Thames Rader but instead call London Information but without being able to explain why.

Anyway Matt, I hope all is going well with the new job at Astraeus.