DEFINITION:

Here we include:

• Agricultural applications of aviation: crop dusting or topdressing.
• Aerial firefighting as the use of aircraft and other aerial resources to combat wildfires. 
• Communications: although the use of aircrafts to deploy communication infrastructures is not the preferred solution (geostationary satellites are the common approach), in some particular cases it has been proposed the use of quasi-stationary flying vehicles (from unmanned planes to airships flying at high altitudes around 20 km) as platforms able to setup a regional communication infrastructure in a much more efficient way than using satellites, allowing flexibility of use in terms of frequent upgrading of the communication payloads and change of the area to be covered.

(Source: Wikipedia: : https://en.wikipedia.org/wiki/Agricultural_aircraft ,  https://en.wikipedia.org/wiki/Aerial_firefighting, https://en.wikipedia.org/wiki/High-altitude_platform_station and PAE own elaboration)