The traffic patern is based upon a number of factors from the aircraft speed to its gliding distance. A 747 will have a different traffic patern to a C152. When training pilots to fly, the traffic patern has a number of purposes; to practice landings and take offs in an efficient manner and to have single engine aircraft where they can safely reach the field in the event of an engine failure, once a very important consideration. In the main the primary reason for flying a circuit is teach a pilot safe procedures and techniques. Because of other traffic LOOKOUT is of primary importance to prevent collisions and to position the aircrat where it can acheive all of the required safety functions. In the main an aircraft downwind should be a wingspan out from the runway therefore, its ground position will depend upon the circuit height and the wingspan. To set a tolerance around a ground track is both meaningless and potentially dangerous; the aircraft is no longer in a position to optimise its performance, something essential in teaching safe operration; the pilot is distracted from essential LOOKOUT by concentrating on totally irrelevant parameters making the likelyhodd of a collision more likely and an unsafe landing quite probable. All these ridiculous requirements should be attacked by using a logical risk assessment which highlights the inherrent dangers of following such illconceived ideas. If it is more dangerous for the pilot and the aircraft, it must be more dangerous for those below.
If maximum noise levels are officially specified, I’m sure sending a person with a noise meter to complainants’ homes would prove the vast majority of such complaints to be frivolous
When applying for planning permission for his already-in-use airstrip, a local farmer had an appointment with planning officials, with noise meters. He flew circuits, while they measured the noise at neighbouring houses. It was a disaster. They could not record the aircraft due to the barking of the collie dogs in the houses, in response to detecting the strangers. He got permission. (The neighbours hadn’t objected) 
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Speaking of hysterical noise complaints, are permissible noise levels in Germany regulated in terms of decibels or in terms of purely subjective disturbance? If maximum noise levels are officially specified, I’m sure sending a person with a noise meter to complainants’ homes would prove the vast majority of such complaints to be frivolous. In many cases, the aircraft noise may not even exceed the average daytime background noise from other sources.
0.1 sm is 160m approx
0.1 nm is 185m approx
Very tight to navigate this by hand, even following a GPS track. The potential wind correction will throw you way off.
Actually when you put it in terms of 150m being 0.1 nm, I take back what I said about being able to fairly easily keep to a 150m corridor. You cant (notwithstanding a GPS/AP combination).
>which is becoming quite popular among German microlighters,
Indeed. We introduced georeferenced maps into PocketFMS & EasyVFR too because of demand from German pilots.
a moving map GPS which has the circuit overlaid
which is becoming quite popular among German microlighters, apparently. Search “www.ulforum.de”" for “Platzrundenmodul” for some illustrative examples.
Even before the Hangelar judgement (thanks for info, by the way!) I could never see the need for such contraptions. Indeed it brings more danger than safety, as dublinpilot pointed out. Especially in the circuit, one must be looking out, NOT peeking at some gizmo screen.
The only way you’d know if you were within 150mtr is by fully zooming in on a moving map GPS which has the circuit overlaid. (Even then, I’m not sure you could achieve it the whole way around the circuit).
But if everyone does that, it’s not going to take any more than a sunny Saturday before planes start to crash and rain down on those below. Keeping to that track while keeping a good lookout is impossible.
This 150m corridor is a bit like the UK situation where a burglar can sue the homeowner if he injures himself on something in your house – e.g. falls into your empty swimming pool and breaks a leg.
The fault is with the justice system which allows such actions (which are so obviously impossible to comply with or in the case of the burglar so obviously contrary to public policy) to proceed, and the fact that some lawyer is sufficiently cynical to have a go at it while keeping a straight face while banking the cheque from a client who obviously has loads of money and nothing to do in his/her life other than to cultivate bees under his/her bonnet and to harrass people.
You can’t do anything about lawyers taking on the job but the justice system needs fixing.
The only way to fly a circuit with the ground track within 150m is with an autopilot following a GPS track, and the top grade of roll steering implementing fly-by waypoints with precise wind correction based on the wind aloft from an airdata computer and the GPS. 150m is about 0.1nm which is about the level of accuracy required at the FAF when flying an ILS or a GPS/LNAV approach, but on those you always have a straight portion before you reach the FAF.
Even if you really wanted to do this, for a laugh, and had the right avionics, there is no chance of being within 150m in the circuit, with the 90 degree turns, and flying slowly, possibly in a strong wind. I went up on Friday and the wind at 1000ft AGL was about 40-50kt so the performance of any system at say 90kt would be, shall we say, entertaining…
Technically possible but I am not aware that anybody has the systems which actually work that way i.e. fly a 90 degree track intercept within 0.1nm with a wind of 50% of your TAS, and do this for all four corners.
I would say that it’s possible to fly that precise in the pattern of your homebase, but it’s really pretty hard to achive at some place you visit the first time. Sometimes you find the pattern easily, but at some fields it’s hard and everybody misses it the first time …
