Currently, this page describes the regulatory situation in the United States. If you have information on other legal systems, please post them below!
Read Federal Aviation Regulation 101 and learn the parts about balloons. All summaries and guidelines provided are not a substitute for direct interpretation and legal advice. A lawyer has not reviewed these suggestions.
We try to design our equipment to be non-hazardous, but also small and light enough to be exempt from regulation. FAA guidelines provide exemptions for small balloons:
101.1a (1) Except as provided for in §101.7, any balloon that is moored to the surface of the earth or an object thereon and that has a diameter of more than 6 feet or a gas capacity of more than 115 cubic feet.
(2) Except as provided for in §101.7, any kite that weighs more than 5 pounds and is intended to be flown at the end of a rope or cable.”
Our size limit is therefore 6ft wide or 115 cubic feet of gas. At sea level, helium provides 7.5lbs of lift for 115cu ft (based on 65.5/1000 cu ft, from pg 68, “A History of Flying” C.H. Gibbs-Smith), 5 lbs is therefore a realistic payload limit for a moored balloon as well. Most of our camera rigs weigh less than 300 grams or 2/3 of a pound, but the string and the balloon itself add to that, though they are not counted as part of the payload.
Also see Near Space by Paul Verhage, which gives good design guidelines for high altitude balloons (which could be any balloon that breaks its moorings) and a summary of FAA regulations as well.
According to the subsequent section of the regulation, unmoored, or free balloons, are regulated if they exceed the following measurements:
(i) Carries a payload package that weighs more than four pounds and has a weight/size ratio of more than three ounces per square inch on any surface of the package, determined by dividing the total weight in ounces of the payload package by the area in square inches of its smallest surface;
(ii) Carries a payload package that weighs more than six pounds;
(iii) Carries a payload, of two or more packages, that weighs more than 12 pounds; or
(iv) Uses a rope or other device for suspension of the payload that requires an impact force of more than 50 pounds to separate the suspended payload from the balloon.
Flying within 5 miles of an airport
When you are within 5 miles of an airport, you need to file a Notice to Airmen (NOTAM), for instance , fill out this PDF request for FAA Form 7711-2 -- a waiver for moored balloons and kites. This requires attaching a marked-up 7.5 series USGS Topographic Quadrangle Map. Then call your local Flight Standards District Office to make contact with someone to email it to for approval.
Once you have this waiver, call the NOTAM hotline: 877-487-6867. Start by saying your state's name and a person will eventually come on the line. Ask them if you need to file a NOTAM, and they will ask you 1) the radial distance from the airport; 2) the height you will be flying (anything below 500 is legal, rather safer to top out at 300); 3) what times you will be flying. For other information, follow this link to find out how to contact your local Flight Standards District Office (FSDO)
Adam Griffith, Liz Barry, and Gina Worth and the Dredge Research Collaborative have successfully gone through this process.
It is also useful to get a Sectional Chart of the local airspace. There is an online map of sectional charts at Skyvector.com. Look out for the take off and landing corridors. This how-to video is an excellent intro to the charts.
Flying a moored balloon at night
Your right to take photographs in public spaces
Read the ACLU's page on photographer's rights for a comprehensive discussion of your right to take photos in public places.
Flying within airport or near seaplanes air space
Although Canadian Aviation Regulations (CARs) does not specify height restrictions, CAR 602.45 states the following with respect to kites:
"Model Aircraft, Kites and Model Rockets
602.45 No person shall fly a model aircraft or a kite or launch a model rocket or a rocket of a type used in a fireworks display into cloud or in a manner that is or is likely to be hazardous to aviation safety."
Further regarding moored kites and baloons:
The standard Public Lab balloon is less than 1.8 m (5.9 feet) diameter when fully inflated (typically 5 to 5.5 feet), and the typical kites used weigh much less than 1 kg (2.2 pounds). So the regulations below are generally not applicable to Public Lab activities.
CHAPTER 11 MARKING AND LIGHTING OF MOORED BALLOONS AND KITES
Chapter 11 governs the marking and lighting of moored balloons and kites.
A balloon that is 1.8 m or more in diameter or exceeds 3 cubic meters of gas capacity, or a kite weighing more than 2.27 kg are marked and lighted in accordance with the requirements specified in Chapter 11.
Markers are attached, during daytime, to the mooring lines of a balloon or to the tether cable of a kite in accordance with this section.
Markers are displayed at not more than 15 m intervals along the mooring lines of the balloon or the tether cable of the kite, beginning at 45 m from the point of attachment on the ground.
Markers required under subsection (1) are:
(a) rectangular in shape, 0.15 m wide and 3.0 m in length; and
(b) of the following colour patterns:
(i) solid orange, or
(ii) of two triangular sections, one of aviation orange and the other aviation white, combined to form a rectangle.
At night, a moored balloon or a kite is equipped with the lighting devices specified in this section.
(a) Lights having the characteristics specified in subsection (2) are located on the top of the object in a fashion as to be viewable from all directions, except that where the dimensions of the object are in excess of 45 m, additional lights of the same type are installed on the top, nose section, tail section, and on the mooring lines or tether cable approximately 5 m below the balloon or kite, so as to define its shape and size; and
(b) Additional lights are equally spaced along the mooring line or tether cable for each 107 m, or fraction thereof, commencing at 90 m AGL.
(a) For operations from 90 m AGL to 150 m AGL, red flashing or white flashing lights of 32.5 effective candelas are installed on the moored balloon and on its mooring lines, or on the tether cable of the kite.
(b) For operations above 150 m AGL, white flashes of 500 effective candela are installed on the moored balloon and on its mooring line, or on the tether cable of a kite.
Lighting required on a moored balloon or on a kite is provided with a means of control such as, for instance a photocell, for day and night time operation in accordance with Table 13-1.