Avoid exceeding legal max altitude

[Joel_t]

Just wondering how you guys avoid exceeding the maximum legal altitude in your area?

I'm in Australia so I have to stay under 400ft to avoid other aircraft from 500ft upwards. I have set the max height warning on my iOSD mini to 120 meters which is about 400ft so I can see when I am coming close to the max height but I've recently realised this height is in relation to my takeoff position where as other aircrafts altitude are all related to sea level. Meaning that obviously if I take off from a location that is 100ft or more above sea level I am actually entering restricted airspace.

Am I correct in thinking this? I've had a search around the forum but can't find anything on the subject.

 

[darwin-t]

That doesn't make sense. Surely, aircraft use the altitude from the ground. At least, that is what would apply in this situation. As long as you stay under 400 feet, that is all you need to worry about.

 

[Joel_t]

That doesn't make sense. Surely, aircraft use the altitude from the ground. At least, that is what would apply in this situation. As long as you stay under 400 feet, that is all you need to worry about.

I thought they set their altimeters before each flight based on barometric pressure to insure they all have the same altitude readings from sea level.

 

[Mal_PV2_Ireland]

Its AGL not ASL

 

[ProfessorStein]

I don't know about the land down under... but in the US, its 400ft relative altitude, not MSL. Which is one of the reasons Phantoms reset to zero on the pad, regardless of the altitude above sea level.

 

[Joel_t]

I don't know about the land down under... but in the US, its 400ft relative altitude, not MSL. Which is one of the reasons Phantoms reset to zero on the pad, regardless of the altitude above sea level.

Thanks for the reply, that makes sense but say if I take off from a mountain 1000ft above sea level and fly 400ft up so I am at 1400ft could I potentially be in the path of another aircraft flying at 1400ft? (I understand they probably wouldn't come within 400ft of a mountain but just as a hypothetical)

 

[sar104]

I don't know about the land down under... but in the US, its 400ft relative altitude, not MSL. Which is one of the reasons Phantoms reset to zero on the pad, regardless of the altitude above sea level.

Thanks for the reply, that makes sense but say if I take off from a mountain 1000ft above sea level and fly 400ft up so I am at 1400ft could I potentially be in the path of another aircraft flying at 1400ft? (I understand they probably wouldn't come within 400ft of a mountain but just as a hypothetical)

Your question has already been answered - it's 400 ft AGL. Anything else would be nonsensical. I live at 7500 ft. Does that mean I cannot fly at all?

 

[Joel_t]

I don't know about the land down under... but in the US, its 400ft relative altitude, not MSL. Which is one of the reasons Phantoms reset to zero on the pad, regardless of the altitude above sea level.

Thanks for the reply, that makes sense but say if I take off from a mountain 1000ft above sea level and fly 400ft up so I am at 1400ft could I potentially be in the path of another aircraft flying at 1400ft? (I understand they probably wouldn't come within 400ft of a mountain but just as a hypothetical)

Your question has already been answered - it's 400 ft AGL. Anything else would be nonsensical. I live at 7500 ft. Does that mean I cannot fly at all?

I understand now that its always 400ft from where you take off for us with Phantoms but what I'm asking is do other aircraft keep 500ft from ground level or do they just stay 500ft above sea level?

 

[ProfessorStein]

I take off from a mountain 1000ft above sea level and fly 400ft up so I am at 1400ft could I potentially be in the path of another aircraft flying at 1400ft?

No... because they are supposed to stay ABOVE 400ft relative (or, as Sar termed it, "AGL").

Ground level. It's always ground level. (Well... okay... not always... but in this circumstance)

 

[Joel_t]

I take off from a mountain 1000ft above sea level and fly 400ft up so I am at 1400ft could I potentially be in the path of another aircraft flying at 1400ft?

No... because they are supposed to stay ABOVE 400ft relative (or, as Sar termed it, "AGL").

Ground level. It's always ground level. (Well... okay... not always... but in this circumstance)

Ah I see, thanks so much for your explanation ProfessorStein

So I guess if I ever took off from a high point and flew over a valley or some sort of drop off I may have to lower my height to remain within 400ft from the ground even though I'd still be within 400ft of my take off position and I guess thats where the iOSD altitude data becomes a bit useless for staying within 400ft.

Thanks again for clearing that up for me. Much appreciated

 

[sar104]

Thanks for the reply, that makes sense but say if I take off from a mountain 1000ft above sea level and fly 400ft up so I am at 1400ft could I potentially be in the path of another aircraft flying at 1400ft? (I understand they probably wouldn't come within 400ft of a mountain but just as a hypothetical)

Your question has already been answered - it's 400 ft AGL. Anything else would be nonsensical. I live at 7500 ft. Does that mean I cannot fly at all?

I understand now that its always 400ft from where you take off for us with Phantoms but what I'm asking is do other aircraft keep 500ft from ground level or do they just stay 500ft above sea level?

In the US, under visual flight rules (VFR):

An aircraft must maintain an altitude of 500 feet above the surface, except over open water or sparsely populated areas. In those cases, the aircraft may not be operated closer than 500 feet to any person, vessel, vehicle, or structure.

 

[TheloniousMac]

In Australia you're pretty free with what you can do, don't get confused with US and UK laws...
Here in Australia that 400 feet restriction is only within 3 nm of an aerodrome and supposedly over a populated city (though not explicitly stated) by CASA.
You can check the aeronautical charts or just use maps and measure a radius around any airport to check if you need to stay under 120 metres altitude.
Aircraft are supposed to stay over 500 feet everywhere except 2 km from their aerodrome but I'm sure they like to do whatever they want for the most part.
A Phantom won't do any more damage than a bird if it strikes an aircraft but as always yield to the larger craft (just like on the road) and use common sense when piloting.

 

[HarryT]

A Phantom won't do any more damage than a bird if it strikes an aircraft but as always yield to the larger craft (just like on the road) and use common sense when piloting.

Most birds don't weigh anything like the 1.5kg of the Phantom, and they're a lot softer and squishier, too . It tends to be big birds, like ducks or geese, that do damage to aircraft.

 

[TheloniousMac]

Most birds don't weigh anything like the 1.5kg of the Phantom, and they're a lot softer and squishier, too . It tends to be big birds, like ducks or geese, that do damage to aircraft.

Fair enough, I guess I was thinking of the birds in my area which actually fly at an altitude similar to the Phantom... Ibis, geese, larger birds traveling in close formations which would actually weigh more than a Phantom combined.
Anyway it would all depend on where it struck.

 

[HarryT]

Fair enough, I guess I was thinking of the birds in my area which actually fly at an altitude similar to the Phantom... Ibis, geese, larger birds traveling in close formations which would actually weigh more than a Phantom combined.
Anyway it would all depend on where it struck.

Absolutely. There was a case last year in the UK where an American military helicopter crashed, killing all crew members, while on a low-altitude night flying exercise. The accident inquiry found that it had been flying at 30m above the ground and had been struck by a flock of geese which knocked both the pilot and copilot unconscious, resulting in the crash. The geese had taken off from an area of marshland, frightened by the noise of the helicopters.

 

[Flying High]

ThelonoiusMac, To clarify, in Australia you are restricted to 400ft AGL in controlled airspace which is pretty well most of Australia, and you cannot fly within 3nm of a registered, certified or military airfield as noted in ERSA. The ONLY exception to this would be as a fully licensed operator who has permission from CASA.
Now the next bit, if you are flying above the ground at 400ft you would in most circumstances be ok as the minimum height for aircraft is 500ft AGL, then there are the anomalies say low level crop spraying or a low level survey aircraft which may have permission to fly at low level, or even someone making a mistake setting their altimeter..... They only have to be 100ft out.
BTW a Phantom could easily take down an aircraft, imagine a light aircraft doing 120kts (about 200kmh) and your Phantom hits the windscreen, I am sure it would go straight through it.

 

[ProfessorStein]

Most birds don't weigh anything like the 1.5kg of the Phantom, and they're a lot softer and squishier, too . It tends to be big birds, like ducks or geese, that do damage to aircraft.

Fair enough, I guess I was thinking of the birds in my area which actually fly at an altitude similar to the Phantom... Ibis, geese, larger birds traveling in close formations which would actually weigh more than a Phantom combined.
Anyway it would all depend on where it struck.

The problem is... a bird the same size/weight as a Phantom can do a LOT of damage! I've seen reports of flocks of geese, and even flocks of smaller ducks, taking down planes... let alone causing severe structural damage.

Always remember... your Phantom is a $1000 replaceable toy. Whereas a larger plane likely has at least one irreplaceable soul aboard. It's pretty easy to see why you shouldn't even risk having the two in the same airspace.

 

[Wedeliver]

i have a question. what about model rockets? small ones easily fly over 400' and big ones can fly at mach one and reach 10,000'. people put cameras on those also. and these are toys just like our quads.

 

[N017RW]

i have a question. what about model rockets? small ones easily fly over 400' and big ones can fly at mach one and reach 10,000'. people put cameras on those also. and these are toys just like our quads.

In the past most r/c (and rocket flying) is done at fixed club or other designated public places (landfills, abandoned airstrips, etc.).
There you often receive training, support, and are required to obey all local regulations (or be sent packing).

Rocket ranges are also limited to their motor size typically to address the safety of nearby aviation activity.
Here again the local club regulates itself and does not allow operation that exceeds their authority.

These a/c make it easy to fly any where by just about anyone so that is why there is such issues or attention to r/c aircraft like I've never seen before in 30+ yrs. as an r/c aviation hobbyist.

 

[Wedeliver]

i have a question. what about model rockets? small ones easily fly over 400' and big ones can fly at mach one and reach 10,000'. people put cameras on those also. and these are toys just like our quads.

In the past most r/c (and rocket flying) is done at fixed club or other designated public places (landfills, abandoned airstrips, etc.).
There you often receive training, support, and are required to obey all local regulations (or be sent packing).

Rocket ranges are also limited to their motor size typically to address the safety of nearby aviation activity.
Here again the local club regulates itself and does not allow operation that exceeds their authority.

These a/c make it easy to fly any where by just about anyone so that is why there is such issues or attention to r/c aircraft like I've never seen before in 30+ yrs. as an r/c aviation hobbyist.

About 20 years ago I bought my sons a model rocket set and we went to the local park and shot the thing in the air all day. I think we probably got close to 400', had no way to tell and really had no idea of any issues, other then don't shoot the rocket at a plane 'cause that would be dumb. I know lots of schools have at times sent up bunches of balloons for some reason without care for planes above.

Since you have been around this stuff for so long, where do you see it going. Can we get some kind of avoidance system? Can our birds broadcast some signal that aircraft could pick up and make it easy to see us. There was a post about a "drone" in canada that came close to a plane. But from the description it sounds like it was a rocket (at 10,000').
The AMA just got the FAA (**** I hate acronyms) to extend by 60 days the public comment period on our interests. I sure hope everyone is putting in their 2 cents.