The answer is stated in ICAO Annex 12 (Search and Rescue)PDF. (See Appendix I relevant to Chapter 5, 5.8 of the Annex.)
Ground-air visual signal code for use by survivors:
Ground-air visual signal code for use by rescue units:
Note 1.— Symbols may be formed by any means such as: strips of fabric, parachute material, pieces of wood, stones or such like ...
Here is the airport diagram for Denver International Airport, which has numerous parallel runways. I don't see any scale that could be used to measure distances. Looks to me that one would have to do some math based on the latitude/longitude information provided, and which is provided here so no interpolation is needed: https://www.airnav.com/airport/KDEN
It's likely to be a flare / flash bang for bird control. Schiphol uses these (amongst a wide variety of methods).
Bird dispersal equipment
There are various resources a bird controller
can use to keep birds away from the runways. Standard equipment
includes a flare gun with noise blanks, a bird alarm call system and a
Likely a flash-bang for runway bird control.
Birds on and near the runway are an ongoing major safety problem (witness the "Miracle on the Hudson", an A320 brought down by a flock of geese shutting down both engines). Measures to convince them to go elsewhere are only ever temporary and of limited effectiveness.
One of the measures that is commonly used ...
The Eurocontrol Lexicon can help here as well. The Estimated In-Block Time is defined as:
The estimated time that an aircraft will arrive in-block.
This is not very helpful, but the definition for Actual In-Block Time is:
The actual date and time when the parking brakes have been engaged at the parking position.
There is very little air traffic control for such airstrips* precisely because there is very little traffic. Even a popular semi-backcountry strip, say Smiley Creek in Idaho, might see a dozen or two planes on a summer weekend. You just use your eyes, and monitor the CTAF and announce your intentions. Other places I might land and camp for several days ...
I can’t speak for Australia, but in the United States there are thousands of uncontrolled airports throughout the country, both privately and publicly operated. Larger, better equipped public uncontrolled airports have good facilities such as paved runways and taxiways, instrument approaches, automated weather reporting stations, pilot controlled airport ...
No. To people at the airport, the electromagnetic radiation from various sources relating to aviation (or anything else) is not dangerous.
Any electromagnetic radiation is, with enough intensity, possibly dangerous, even instantly lethal, but you can rest assured, that such intensities are not present anywhere a normal person has access to.