Mid air over Hertfordshire

[Aussie Andy]

Hi VP,

Yes I had heard of the Qinetiq project too, but have not heard of any update since last Summer (ref. http://www.rin.org.uk/pooled/article..._NEWSART_66107).

I suppose this discussion should really be about whether we want the open FIR to become either controlled airspace, or whether in addition to transponders we want all flying machines to be equipped with TCAS as well.

Well, I'm all for the Open FIR but I don't see why we couldn't have some low-cost improvement to the BNN - BPK - LAM corridor which is quite a choke-point these days. We should be clear that there is no proven link between the accident which triggered this thread and the issue we are debating now, but still it seems there may be a case for enhancing safety in that area if possible.

Why not optional blind-calls on a special "north London lane" frequency? Maybe there is a case for a "south London lane" also, i.e. BLK - OCK - BIG? Cheap and easy to implement, and the template for this sort of operation exists elsewhere (e.g. LA as described above, and also similar "V1" low-level route along Sydney beaches in Australia).

Meanwhile, I also think there may be a case for mandatory mode-C within 30NM of LON... just like the "mode C veil" they have surrounding Class B airspace (e.g. SFO) in the US. Why not? I think (but this may be ignorance on my part) that it's not as big an issue to fit SSR transponders to microlights as it is to gliders, so I presume microlights could cope with this if they had to (yes?).

And as far as gliding goes, although there is gliding within the 30NM, e.g. Lasham is about 28NM, Dunstable (London Gliding Club) about 24NM and Wycombe about 15NM for example, I think it would be possible to declare segments of airspace where gliding is permitted without transponders, avoiding IFR approaches, which AFAIK wouldn't imply much - if any - change to their current freedoms. Gliders don't transit what I described above as the "north" or "south" London lanes, do they? If not, then would it be OK if they were excluded from the "north" and "south" lanes? That way, the lanes would effectively be mandatory mode C.

Before anyone says it, I know this leaves scope for pilot error, forgetting to switch the transponder on or forgetting to put it into mode C (sorry to say, I managed to do this myself last week... didn't notice until Brize asked me to cycle the transponder !), but I think that together with the optional blind calls on a dedicate "lane" frequency these measures a) wouldn't cost much; b) wouldn't curtail anyone's freedoms too much, and c) might just help make these choke points safer. And if it were marked on the charts "north London lane - mandatory mode C, self-announce when entering and leaving on freq XXX" then you would be less likely to forget..!

But I wouldn't be surprised if someone tells me I have some dangerously wrong assumptions in the above... looking forward to hearing what others think. Maybe if there is some concensus we could ask our AOPA what they think and if its worth lobbying for. I for one would put (a little bit!) of energy into this!

Andy

[bar shaker]

WWW

You are living in a dream world.

Neither of your options is going to happen.

[robin]

Well said Bar Shaker

What is actually needed is for there to be fewer pinch points - not to increase controlled airspace. I'm trying to think of the last time I got anywhere near an airliner in flight - no, still can't.

I was at an airfield once where the ATCO got in a paddy because there were 4 aircraft in the circuit. He said if anyone else asked to join he would go off-duty and declare the airfield unlicenced.

Compare that with the Rally or a Popham event where many more aircraft (generally) fly in safely, using see and avoid.

On my earlier point, does anyone know the arc of coverage of TCAS - is it just forward pointing, and how far up and down does it look? If so how does TCAS protect you from someone who's electrics have failed or where they've forgotten to switch it on?

[bar shaker]

I think a simple review of where the schools in this area do their training could make a major contribution to safety in the corridor.

Look at it this way. Almost all traffic in the North London Corridor is either flying East/West or is going up/down the Lea Valley. At present, the only other traffic is going to be students, doing stalls, 60deg turns, PFLs, climbing and descending... all in the UK's busiest bit of sky and with a low ceiling.

Such a move would also cost nothing as there are open areas a few miles to the east and west and could be implemented this weekend.

Fitting transponders will achieve nothing if there is not also the budget and resources to provide a good RIS in the area. And there isn't.

[bookworm]

I think you're likely to need a battery of some sort for practical reasons, regardless of the power source requirements. But I'm not sure about "hefty" -- battery technology move rapidly.

The strobe thing died because of install costs. I'll try to find out more about the low power lightweight transponder and report back.

Fundamentally, the transponder is the wrong approach. What would be far more effective is an ADS-B system, where each aircraft broadcasts its position periodically. This is already on trial in the US. Garmin has developed the UAT datalink avionics -- I don't have the spec but I don't think the power consumption is high.

[IO540]

"it would rely on 100% illumination of all airspace by a primary radar, in order to trigger all the transponders in the first place."

The (presently) £20k+ GA systems are active and don't rely on SSR activity. I had a quote for a passive-only system for about £15k. These all return the azimuth to the target, and are pretty accurate. There is no reason why a passive system could not be sold for far less than £15k; the technology is straightforward and SSR trigger availability isn't a problem.

Also I can't see the difference between one transponder returning 1 watt (at a given distance) and another transponder returning 100 wats (10 times further away). The former one will need to be 10 times nearer for the same visibility but for TCAS purposes that would be just fine.

[robin]

>>I had a quote for a passive-only system for about £15k<<

Bl**dy h*ll - thats £3k more than my plane is worth.........., and £6k more than I got for my last one.

[TonyR]

Can we have a bit of common sense please. How often do mid airs happen?

Ho often does an airliner have to do a steep turn to avoid a light aircraft?

I for one don't want this ***** in my aircraft, CAS was designed to protect IFR traffic and when I fly in CAS I don't mind using Mode C etc.

When I fly from home outside CAS I just want to have FUN, No radio, No transponder, just look out the bloody window and have a bit of FUN

Tony

[Shaggy Sheep Driver]

Well said, TonyR.

1) Keep a sense of proportion.

2) Don't look to technology to take the place of basic airmanship.

3) Be careful what you wish for (value our current - but reducing - flying freedoms).

And (4), a note to the airline industry:

Don't expect 'fly for fun' VFR bimblers outside controlled airspace to carry thousands of pounds worth of electronics (which might call for power the aeroplane hasn't got, and which will require expensive maintaining and fixing from time to time) to make your life easier, but which are of no benefit to said bimblers.

SSD

[IO540]

That reason I would never spend that sort of money on traffic detection is because much or most traffic in Class G is non transponding, so it's a near-complete waste of money.

Nobody should moan about somebody spending the money though; it's a free world. Lots of GA planes are worth £200k+ - so what?

What people do moan about is having a mandatory transponder, and that should not be the big deal that it is made out to be.

[Aussie Andy]

Hi guys,

It strikes me that the people least concerned about congestion in the north/south London corridors variously appear to live in Cornwall, Northern Ireland and Cheshire. Perhaps if you flew through these lanes more often you'd be more interested in the self-announce blind-calls idea? (I appreciate that the Manchester/Liverpool LLR is a similar situation, but if SSD is happy with it as it is then perhaps that is because the traffic densities "oop north" are lighter than "darn sarf"?) I also note that another opponent of these ideas has only been flying 1 year according to his profile: maybe your views will change over time...

The benefit of transponders and e.g. the 30NM mode C veil in the US is different: its to help out the chaps in the controlled airspace and the radar controllers. But if it doesn't cause too much grief for the thriving recreational GA community in the US, why should it be too tough for us here?

ADS-B is a great idea, but its not going to solve the problem of the congested lanes... but as implemented in the Alaskan Capstone programme it requires a data-link radio and GPS to be fitted to aircraft as well as other expensive displays etc (ref. http://www.alaska.faa.gov/capstone/p.../slide0223.htm)so you might be barking up the wrong tree there if your goal is to avoid the cost of a transponder!?

Other than the special case of gliders, and maybe ultralights(?), I don't see that carriage of a mode-C transponder is onerous: the vast majority of rental a/c have a transponder fitted as standard in my experience.

Seems I'm a bit of a lone voice on the idea of a "lane" frequency... hey ho!


Andy

[TonyR]

AA,

I fly to the London area usually and on to France every week and I have a mode C, but when I fly VFR I like to look out.

I am not against anything that will help us stay safe, I just don't think we should be forced to spend thousands on equipment that will make very little if any difference to airprox or mid airs.

And before you start counting again I've been going 30 years and have 3 airprox incidents, the last one was an aircraft out of Blackpool and I was out of Leeds.

We both arrived at POL VOR at the same time and the same alt, by the time the Leeds ATC saw him pop up on RAD we had both turned right and passed by about 50 feet, both in light twins at a closing speed of well over 300 knots, but were both VFR and looking out.

Perhaps this has made me more than a little concerned about the value of FIS or RIS when flying around hills etc, and the often minimum information shared between ATC units.

Tony

[robin]

>>>Nobody should moan about somebody spending the money though; it's a free world. Lots of GA planes are worth £200k+ - so what?<<<

Er....... I have no objection to people spending the money in the way they wish. I just have a slight problem (called a bank manager).

I think this debate may start to go down a route which could get nasty.

Just what is GA?? Does this include the 1000s of gliders, PFA types and 'recreational' pilots, cos I know no-one with shares in planes worth 1/4 of that amount. We are just as much safe pilots as those flying the bigger jobs - possibly even safer, as we don't have autopilots.......

I often fly in the Welham Green area also in the corridor near Booker and would object to another implied suggestion that lightly equipped aircraft should not be permitted to access that airspace.

This accident may prove to be one that is just that - a tragic accident. Look at the videos at a CAA Safety evening. Mistakes do happen and in the air they may well lead to fatalities. But that is part of life and is a non-escapable hazard of flying.

So long as we do our best in the air using best available technology not incurring excessive cost (as the Environment Agency say), that's all we can do

[QDMQDMQDM]

A £9,000 per aircraft phased introduction of a bang up to date technology that means you know precisely about 99% of the traffic 99% of the time and reduces the numbers of PPLs killed every year and totally avoids a)

What utter rubbish. You are dreaming.

And if Mode A is such a problem for the TCAS, why not just ban Mode A?

QDM

[andrewc]

If you fly under the Schipol TMA (<1500') the controllers
ask you to switch off mode-A transponders and mode-C
transponders which aren't giving an accurate altitude
read-out to them.

This applied under the London TMA might well alleviate a
lot of the problem heavy traffic has with GA under their
controlled space. That said a reasonable quid-pro-quo
for that restriction would be the provision of some dedicated
LARS for the Luton / Stansted corridor.

I'm not sure about the truth of most traffic being
transponder-less...my experience with Skywatch, an
active-TCAS system, on a Cirrus SR-22 is that it detects far
more aircraft than you would normally see while keeping a
good visual look-out. In fact it makes you realise exactly how
busy the south-east is with aviation traffic.

-- Andrew

[Shaggy Sheep Driver]

It strikes me that the people least concerned about congestion in the north/south London corridors variously appear to live in Cornwall, Northern Ireland and Cheshire. Perhaps if you flew through these lanes more often you'd be more interested in the self-announce blind-calls idea? (I appreciate that the Manchester/Liverpool LLR is a similar situation, but if SSD is happy with it as it is then perhaps that is because the traffic densities "oop north" are lighter than "darn sarf"?) I also note that another opponent of these ideas has only been flying 1 year according to his profile: maybe your views will change over time...



Thank you AA for pointing out how sleepy airborn life is for us provincials out in the sticks. Have to try that one on Manch App next time I want a VFR clearance.

Some of us, BTW, have been known to venture south of the Watford gap from time to time, and actually - we don't notice much of differerance. Wonder why that should be? And some of us who'se views differ from your own have been flying for a tad more than a year.

Glad you metioned the LLR. Most southern pilots of my aquaintance think it be haunted by dragons, such is their fear of that 5 mile by 1500 foot corridor. Biggest thing I ever met in there was a Lancaster with Hurricane on one wingtip and a Spitfire on then other; got a salutary barrell roll from the Spit as we passed, one vintage British taildragger to another.

Keep it proportion, AA.

SSD

[ShyTorque]

"If you fly under the Schipol TMA (<1500') the controllers
ask you to switch off mode-A transponders and mode-C
transponders which aren't giving an accurate altitude
read-out to them. This applied under the London TMA might well alleviate a lot of the problem heavy traffic has with GA under their
controlled space. That said a reasonable quid-pro-quo
for that restriction would be the provision of some dedicated
LARS for the Luton / Stansted corridor".


For goodness sake, NO! Please do NOT switch off your Mode A transponder, least of all in that congested piece of airspace with its chokepoints! A TCAS return without an altitude readout, whilst giving only a general warning of a possible confliction, is better than nothing. Some of us fly aircraft with TCAS outside controlled airspace, it is in all our interests to publicise our presence to other pilots. Even better, if you have mode C please use that all the time. An effective lookout is the only real answer in VMC but TCAS helps enormously, especially in marginal weather.

In the worst case, if the cloudbase is below MSA, the cloud up to 2400 feet under the London TMA (Class G airspace) is quite likely to contain aircraft legally and necessarily operating under IFR and IMC. A TCAS alert without a mode C altitude marker puts the IMC pilot in a real dilemma as he probably cannot climb more than a couple of hundred feet and that may not be the correct action in any event. As already pointed out, TCAS azimuth accuracy is not assured! But at least he/she will go to "much enhanced alertness" (actually, the hairs on the back of the neck stand up very quickly in my case). If the other aircraft isn't fitted with TCAS, and it's unlikely if mode C isn't, at least one pilot is aware and may be able to resolve the conflict with the help of ATC or intuition.

Be aware that an aircraft "scud-running" may be only just clear of another aircraft above in cloud, or no separation may exist at all.

[Flyin'Dutch']

Tragic.

Would it not be better if we discussed the rest of the issues raised elsewhere?

FD

[Aussie Andy]

Hi guys,

TonyR:

this has made me more than a little concerned about the value of FIS or RIS

... I'm not arguing with that point... Perhaps there are too many criss-crossing arguments too keep track of (for me!)... What I am in favour of is a self-serve blind-calling frequency in the crowded London lanes: costs nothing and enhances safety. I also happen to be in favour of the mode-C veil system, as used in the US.

andrewc: I have flown under the Schiphol TMA too and been asked by ATC to "squawk standby" (not mode-A) especially when passing under the approach path.. but the big difference there is that you must be in communication with the APP guys (even if just FIS) so they know about you. This avoids generating TCAS alerts when the approaching a/c are only say 500' above you as you scoot over e.g. the PAM VOR.

SSD: I somehow knew I risked winding you up Not intended that way..!

So, anyway, does anyone object to the idea of dedicated A/A freq's for the n/s London lanes? If so I would be interested to understand that argument.

Cheers!

Andy

[AlanM]

As an ATCO I am in despair at the suggestion of asking an aircraft to turn Mode C off. (OK, if it is outside the 200feet legal tolerance that is different)

What are the legal "duty of care implications" of me telling everything in the BPK-BNN-LAM area to turn off the Mode C - when a TCAS equipped aircraft (as ShyT says there are loads of TCAS equipped Heli's in the area) - not to mention Citation, LearJet and even 737's out there on a regular basis has a midair!

The idea of a freq where blind transmissions are made sounds good. It works well under the Jo'burg TMA..... When I flew there everyone made accurate calls and we responded accordingly - but it wasn't exactly busy. For our area, When should they be on the blind freq? What if there is other IFR traffic in the area?

Who knows what the solution is. (apart from a London LARS FULLY funded by the CAA!!!!!!)