Can you answer this airspace question?
Thread Starter
Join Date: Nov 2014
Location: Melbourne
Posts: 37
Likes: 0
Received 0 Likes
on
0 Posts
Can you answer this airspace question?
Here's a Doozy:
You are at a non-controlled airfield (elevation 2700 ft and situated on flat non-populous terrain in Class G Airspace) and the base of an extensive layer of stratocumulus has been confirmed at 4000 ft AMSL but visibility exceeds 10 km. Can you legally take off in a radio-equipped aircraft and depart the airfield?
A. Yes but only maintaining radio watch and you may not climb above 1000' AGL
B. Yes but only maintaining radio watch and you may not climb above 500' AGL
C. Yes but only maintaining radio watch and you may not climb above 3000' AMSL
D. No
You are at a non-controlled airfield (elevation 2700 ft and situated on flat non-populous terrain in Class G Airspace) and the base of an extensive layer of stratocumulus has been confirmed at 4000 ft AMSL but visibility exceeds 10 km. Can you legally take off in a radio-equipped aircraft and depart the airfield?
A. Yes but only maintaining radio watch and you may not climb above 1000' AGL
B. Yes but only maintaining radio watch and you may not climb above 500' AGL
C. Yes but only maintaining radio watch and you may not climb above 3000' AMSL
D. No
Firstly is the intent to operate VFR or IFR?
Assuming it is a VFR Operation and not being aware of the Local Regulations in your country but looking at ICAO, I would say the Answer is "D - NO"
ICAO Annex 2 - 3.9 VMC visibility and distance from cloud minima
In Class G Airspace
At and below 900 m (3 000 ft) AMSL, or 300 m (1 000 ft) above terrain, whichever is the higher - Flight visibility 5KM - Distance from cloud: Clear of cloud and with the surface in sight
Below 3 050 m (10 000 ft) AMSL and above 900 m (3 000 ft) AMSL, or above 300 m (1 000 ft) above terrain, whichever is the higher - Flight visibility 5KM - Distance from cloud: 1 500 m horizontally 300 m (1 000 ft) vertically
So using the above the only option would be C not above 3000 AMSL, However, making the assumption that the "Extensive layer of stratocumulus" covers a distance beyond the vicinity of the airport (more than 5NM)
ICAO Annex 2 - 4.6 Except when necessary for take-off or landing, or except by permission from the appropriate authority, a VFR flight shall not be flown:
a) over the congested areas of cities, towns or settlements or over an open-air assembly of persons at a height less than 300 m (1 000 ft) above the highest obstacle within a radius of 600 m from the aircraft;
b) elsewhere than as specified in 4.6 a), at a height less than 150 m (500 ft) above the ground or water.
As the elevation is 2700ft, you would only be able to cruise at 300ft AGL and would not be able to comply with (b).
Lastly ICAO Annex 11 Appendix 4 states for VFR Traffic in Class G Airspace Radio Communication is not required, therefore Options A to C would be invalid.
This answer of "No" is based purely on ICAO and not on local regulations as some countries allow flights below 500ft AGL without nuisance or danger to persons or property and Communication may be required in some countries in Class G airspace as per local regulations.
Assuming it is a VFR Operation and not being aware of the Local Regulations in your country but looking at ICAO, I would say the Answer is "D - NO"
ICAO Annex 2 - 3.9 VMC visibility and distance from cloud minima
In Class G Airspace
At and below 900 m (3 000 ft) AMSL, or 300 m (1 000 ft) above terrain, whichever is the higher - Flight visibility 5KM - Distance from cloud: Clear of cloud and with the surface in sight
Below 3 050 m (10 000 ft) AMSL and above 900 m (3 000 ft) AMSL, or above 300 m (1 000 ft) above terrain, whichever is the higher - Flight visibility 5KM - Distance from cloud: 1 500 m horizontally 300 m (1 000 ft) vertically
So using the above the only option would be C not above 3000 AMSL, However, making the assumption that the "Extensive layer of stratocumulus" covers a distance beyond the vicinity of the airport (more than 5NM)
ICAO Annex 2 - 4.6 Except when necessary for take-off or landing, or except by permission from the appropriate authority, a VFR flight shall not be flown:
a) over the congested areas of cities, towns or settlements or over an open-air assembly of persons at a height less than 300 m (1 000 ft) above the highest obstacle within a radius of 600 m from the aircraft;
b) elsewhere than as specified in 4.6 a), at a height less than 150 m (500 ft) above the ground or water.
As the elevation is 2700ft, you would only be able to cruise at 300ft AGL and would not be able to comply with (b).
Lastly ICAO Annex 11 Appendix 4 states for VFR Traffic in Class G Airspace Radio Communication is not required, therefore Options A to C would be invalid.
This answer of "No" is based purely on ICAO and not on local regulations as some countries allow flights below 500ft AGL without nuisance or danger to persons or property and Communication may be required in some countries in Class G airspace as per local regulations.
Thread Starter
Join Date: Nov 2014
Location: Melbourne
Posts: 37
Likes: 0
Received 0 Likes
on
0 Posts
Good response. It is an Australian question, and looks like VFR.
I believe most of your analysis is correct, but I also note that the question states non-populous area, and flat terrain, so the low-flying limit then becomes 500 feet. At 500 feet AGL I would be over 3000 feet AMSL, however, by stress of weather, when I am within 1000 feet of the ground and able to see it, I merely have to be clear of cloud, and that rule is in operation above 3000 feet AGL.
So per my understanding of the question, the flight it is allowed.
I believe most of your analysis is correct, but I also note that the question states non-populous area, and flat terrain, so the low-flying limit then becomes 500 feet. At 500 feet AGL I would be over 3000 feet AMSL, however, by stress of weather, when I am within 1000 feet of the ground and able to see it, I merely have to be clear of cloud, and that rule is in operation above 3000 feet AGL.
So per my understanding of the question, the flight it is allowed.
But at 500ft AGL from an elevation of 2700ft you would be at 3200 ft AMSL over a non populous area, and according to Annex 2, above 3000ft AMSL but below 10000ft AMSL, you need to be 1000ft vertically from cloud. If you operated at 500ft AGL (3200ft AMSL) you would be 800ft vertically from cloud (where the base is 4000ft) and therefore busting minima. So I would still say the answer is No you cannot fly.
Once you climb through 3000ft AMSL you have to comply with the higher minima for cloudbase, because operating 1000ft vertically from cloud would put you only at 300 ft AGL and below the low flying limit.
Once you climb through 3000ft AMSL you have to comply with the higher minima for cloudbase, because operating 1000ft vertically from cloud would put you only at 300 ft AGL and below the low flying limit.
At and below 900 m (3 000 ft) AMSL, or 300 m (1 000 ft) above terrain, whichever is the higher - Flight visibility 5KM - Distance from cloud: Clear of cloud and with the surface in sight
Sorry I did not quote the whole table text in by description, so I'll attach it for reference.
The 1000ft AGL extends into the the altitude band of 3001ft-10000ft AMSL - Once you go through the 3000ft AMSL band you have to comply with 1000ft vertically from cloud.
So sorry but NO you cannot go.
The 1000ft AGL extends into the the altitude band of 3001ft-10000ft AMSL - Once you go through the 3000ft AMSL band you have to comply with 1000ft vertically from cloud.
So sorry but NO you cannot go.
Thread Starter
Join Date: Nov 2014
Location: Melbourne
Posts: 37
Likes: 0
Received 0 Likes
on
0 Posts
Thanks for sending me that, that is what I was looking for. But I don't think you read it right. You missed a line.... "3000 feet or 1000 feet above terrain ***WHICHEVER IS THE HIGHER*** ". So per that, I can go over 3000, in fact I could be way up at 7500 feet clear of cloud as long as I am 'within 1000 feet of land'. All good. And in non-populous, I can be at 500 feet AGL without breaking any rules.
So looks to me like the flight is still on!
So looks to me like the flight is still on!
Ah yes - I have misinterpreted this (for most of my career then) sometimes pictures help.
And looking at the link shared by Megan it is clear.(Although Aussie rules are quite different in Class D airspaces) The flight would be legal if it remained between 500ft and 1000ft AGL in a non-populated area and clear of cloud.
I agree now that the flight can still be on!
And looking at the link shared by Megan it is clear.(Although Aussie rules are quite different in Class D airspaces) The flight would be legal if it remained between 500ft and 1000ft AGL in a non-populated area and clear of cloud.
I agree now that the flight can still be on!
Join Date: Aug 2011
Location: UK
Age: 53
Posts: 0
Likes: 0
Received 0 Likes
on
0 Posts
ME, you inferred at post #3 you are after Australian requirements, yes you can go is my take.
https://vfrg.casa.gov.au/operations/...al-conditions/
https://vfrg.casa.gov.au/operations/...al-conditions/
Join Date: Aug 2011
Location: UK
Age: 53
Posts: 0
Likes: 0
Received 0 Likes
on
0 Posts
Australian Requirements
At or below (whichever is the higher) of:
(a) 3000 ft AMSL;
(b) 1000 ft AGL
Flight Visibility 5000 m
Distance from cloud - Clear of cloud and in sight of ground or water
Additional conditions - Radio must be carried and used on the appropriate frequency
At or below (whichever is the higher) of:
(a) 3000 ft AMSL;
(b) 1000 ft AGL
Flight Visibility 5000 m
Distance from cloud - Clear of cloud and in sight of ground or water
Additional conditions - Radio must be carried and used on the appropriate frequency
