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400 Feet (120m) height restriction for models over 7.5kg.


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11 minutes ago, Frank Skilbeck said:

If you would like to view your height and other parameters in graph and map form then the https://aerobtec.com/altis-gps/ units are worth a look. They also provide telemetry feedback on most radio systems.

Looks good. Not a bad price either. Couldn't find price on the link above but found it at £65 elsewhere.

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After reading through much of this thread surely the 400' limit was imposed because the minimum altitude for light aircraft is 500' thus giving in theory a positive separation?

I appreciate the CAA have given the BMFA, LMA authority to grant exceptions but if granted too liberally it will increase the chances of an Airprox report. Too many of those, there have been two this year, and we could be back to square one.

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Increased visibility of model flying sites as a result of responsibly issued permits might also reduce the potential for conflicts.  The process appears to involve a reasonably robust risk assessment and I would like to think that whoever deals with applications at the BMFA will use their experience and professionalism to assess applications sensibly.

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6 hours ago, john stones 1 Moderator said:

Got no argument with the telemetry comments, times change and you should move on, brings to mind, how did club manage this before this technology was there ?

The other thing to bear in mind, is when I started flying a 60 powered model was considered a large model, it's only in the last 10 years or so that larger petrol engines have become more common place, but noise is probably what holds them back as much as the height limit.

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11 hours ago, Simon Chaddock said:

After reading through much of this thread surely the 400' limit was imposed because the minimum altitude for light aircraft is 500' thus giving in theory a positive separation?

I appreciate the CAA have given the BMFA, LMA authority to grant exceptions but if granted too liberally it will increase the chances of an Airprox report. Too many of those, there have been two this year, and we could be back to square one.

 

Easy for you to say Simon. Your large models barely weigh 0.75kg, let alone 7.5kg ?.

I take your point though.

 

I'm more of the opposing view, similar to that posted by @Martin Harris - Moderator.

 

Publishing the club site's position within the AIP should result in awareness of the site's presence, and therefore separation of manned aircraft from ALL models, not just large ones. Note that I said "separation" and not "increased separation". Remember that a model weighing 7.1kg can legally fly within the same airspace as light aircraft. The number of encounters with manned aircraft and therefore Airprox reports should reduce once a club has a BMFA Site Permit and it's associated entry within the AIP. It certainly puts the club in a stronger position, when arguing it's case after an Airprox report.

 

10 hours ago, Martin Harris - Moderator said:

Increased visibility of model flying sites as a result of responsibly issued permits might also reduce the potential for conflicts.  The process appears to involve a reasonably robust risk assessment and I would like to think that whoever deals with applications at the BMFA will use their experience and professionalism to assess applications sensibly.

 

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22 minutes ago, john stones 1 Moderator said:

Noise ?

 

Good question, but are you suggesting that >7.5kg models make more noise than smaller petrol engined ones? This is not my experience, but there are exceptions. The problem of noise is usually due to people using the "exhaust deflectors" supplied with the engine rather than investing in an effective silencer. This is something that can be managed by the club and is a completely separate issue to the model's MTOM.

 

Are you also suggesting that models flying above 400 feet are noisier than those below? I can see that models flying higher, might fly further out but surely this is more to do with the person flying rather than the size of the model. Smaller models which may be louder or equally noisy and even have the same engine and exhaust fitted are already allowed to fly above 400 feet, so why would the MTOM have any baring on noise?

 

Edited by Gary Manuel
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1 hour ago, Gary Manuel said:

 

Good question, but are you suggesting that >7.5kg models make more noise than smaller petrol engined ones?.... 

 

....Are you also suggesting that models flying above 400 feet are noisier than those below?

 

1 hour ago, john stones 1 Moderator said:

Yes.

And Yes again.

 

A model further away cannot be noisier than the same model at closer range - that is just physics (remarkably this is one of the very few things I can remember from secondary school!). The sound is attentuated by the air and other objects, and decreases by ~6Db for each doubling of distance.

 

However, it is true that the ground area over which the model can be heard will increase with altitude (up to a point), but the volume at any given point within that area will still reduce as altitude increases. Put another way, a model 800ft directly above you will be ~6Db quieter than the same model 400ft above you, but at 800ft an increased number of people will be able to hear it as the area the sound reaches is bigger. That may or may not lead to increased disturbance/noise complaints, but it's not a clear cut yes/no.

Edited by MattyB
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Just now, MattyB said:

 

 

A model further away cannot be noisier than the same model at closer range - that is just physics (remarkably this is one of the very few things I can remember from secondary school!). The sound is attentuated by the air and other objects, and decreases by ~6Db for each doubling of distance.

 

However, it is true that the ground area over which the model can be heard will increase with altitude (up to a point), but the volume at any given point within that area will still reduce as altitude increases. Put another way, a model 800ft directly above you will be ~6Db quieter than the same model 400ft above you, but at 800ft a an increased number of people will be able to hear the model as the area over which the sound can be heard is bigger. That may or may not lead to increased disturbance/noise complaints, but it's not a clear cut yes/no.

 

Yes

And Yes Again Matty.

However, I may just be ticking boxes and have other opinions at the appropriate place.

Next please.

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1 hour ago, john stones 1 Moderator said:

 

Yes

And Yes Again Matty.

However, I may just be ticking boxes and have other opinions at the appropriate place.

Next please.

 

Strange debating technique if I may say John; throwing a previously unmentioned factor into the equation, then refusing to discuss it, despite reasoned arguments from other posters.

 

Anyway, now that we are actually addressing the original thread question of whether clubs should apply for a BMFA Site Permit, let me throw in another couple of factors.

 

1. Open days.

The recently issued BMFA Handbook now includes Annex A - The BMFA Model Flying Display Handbook. In addition to defining the requirements and providing (very good) advice for organising "Flying Displays", it also covers "Contests and Events (Not a Display)". These are described as Tier 1, 2 or 3 according to the MTOM as below. A club open day is an "Event" and clearly, if models over 7.5kg are to be flown over 400 feet at one of these events, then the requirements of Tier 2 apply. Tier 2 requires a BMFA Site Permit.

 

1415049047_25-05-202117-06-26.jpg.c3ff1a2ffa1cc09a6277a1a30bff633d.jpg

 

2. Practice for flying displays, open days and away days.

 

Obviously anyone who plans on participating in a flying display or club open day needs to practice their routine before they attend the event. It is in fact a CAA requirement that any pilot operating in a display has practised at least one full routine within the previous 30 days. Where are they going to undertake the practice with their >7.5kg model unless their club has a BMFA Site Permit?

 

P.S. I see "Practising of aerobatic routines" as the main justification for the BMFA Site Permit. It is apparently one of the questions on the application form.

 

Edited by Gary Manuel
Why are typos only spotted seconds after posting?
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So back to my original question. Should clubs be applying for a BMFA Site Permit or not?

The CAA have given the responsibility of issuing these permits to the BMFA, who in turn have put an awful lot of effort into making it easier for clubs to apply. It appears to me that they have done this because they see it as a good thing. Hopefully, we will hear from the BMFA soon so that we can understand what their advice is in this respect.

Edited by David Ashby - Moderator
edited at poster's request.
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On 24/05/2021 at 13:36, Martin Harris - Moderator said:
On 24/05/2021 at 03:09, Mike T said:

It very much depends on the model. As our field is located in controlled airspace, I’m been very aware of the legality of larger model flying and have had proactive dealings with the airport and NATS on many occasions. 
 

My 1/4 scale Cub and Maher’s Pacer are regularly flown to just below 400’ and looping manoeuvres and spins can be achieved comfortably within this ceiling. This would not be the case with a scale jet of similar size of course.  Telemetry alarms are a great reassurance that I’m not inadvertently climbing into prohibited airspace and I have programmed a telemetry control to bring the throttle to idle at a smidgeon under 400’, restoring power at 350’ as an additional precaution. 
 

Noise constraints mean that models such as 100cc aerobats aren’t common at our field - easy for an average club flyer to exceed 400’ with that sort of model - but we’ve had visits from the Azza Aerosport’s team and they managed to put on very accomplished demos within such a ceiling. 

 

Expand  

Unless there's another Mike T on the forum, I'm pretty sure I didn't post that!  ?

Spookily, I do have a 1/4 scale Cub.  I also have a Mahers Pacer - but that's still in its box in the attic! ?

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Afternoon all.

Well I killed this thread and left a bad smell, let's see If I can bring it back to life. First off my apologies to all concerned, I behaved badly and let the other mods down.

 

Gary Manuel ? I'd fly anywhere, anytime with the man, I have no worries about the likes of him endangering our club, he's a good member.

 

Getting a permit to fly big stuff higher, Is No for me, worried about getting something we've never had, a noise complaint, Gary would sort his models and quieten them, others ?

I don't want to take the risk.

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20 minutes ago, john stones 1 Moderator said:

Getting a permit to fly big stuff higher, Is No for me, worried about getting something we've never had, a noise complaint, Gary would sort his models and quieten them, others ?

I don't want to take the risk.

 

OK, but if you already have a maximum noise level set in your club rules and everything has to pass that anyway I'm not sure why the size of the model matters? After all you could have a model on the max noise limit now that is <7.5kg and could be flown at >400ft now (assuming you don't already have a 400ft height limit in your existing rules). If members are worried about an increased noise footprint at ground level with height you could even have a lower noise limit for large models flown over 400ft I suppose, though that might get complicated to administer. 

Edited by MattyB
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Thanks John. No hard feelings I hope.

 

I've had another thought. What has not been mentioned so far is that the entry in the AIP could potentially be used in the future for route planning by autonomous drones - geofencing data? Could it be that a Site Permit will effectively force these sky robots to divert around us?

 

It could if done properly (so it probably won't).

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12 minutes ago, Gary Manuel said:

Thanks John. No hard feelings I hope.

 

I've had another thought. What has not been mentioned so far is that the entry in the AIP could potentially be used in the future for route planning by autonomous drones - geofencing data? Could it be that a Site Permit will effectively force these sky robots to divert around us?

 

It could if done properly (so it probably won't).

 

None here Gary, I'll leave you to it.

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Flicked through most of the above which is all very well if we all flew with bells and whistles voice telemetry gear but we don`t. Even if it is displayed on the Tx screen it would be extremely dangerous to look down and then find it. The size/weight of a model does not realistically come into the equation and becomes irrelevant if you are thinking of a possible collision with a full size aircraft.

Most responsible flyers will stay well clear if one approaches and even a glider on landing finals will be very visible.

All of this is hypothetical anyway because a) our eyes cannot judge distance that well even with the ground as a reference and b), certainly not with a blank sky to look at. Try estimating if a moving light in the night sky is a high flying aircraft, a fast satellite or a UFO.

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