Safe approach of a crash site can be difficult.

But go to the basics, Pause before you enter the site, Look, Listen, and Smell.

Look for any signs of smoke or fire, if in woodland look in the trees for broken branches of aircraft parts and do not walk under them.

Listen for and metrical sounds I have had jet engines that the starter motor has be running for at least a day after the crash. Also listen for survivors.

Smell for smoke but more inportly fuel smell with a light plane it will be gas, for a jet it will smell like kerosene.

Next look at your route in and out of the crash site. You should try to approach from up wind and level with the site. Fuel fumes tend to travel down hill and down wind but if it goes up the flash will travel uphill from the site. Look at the ground and up in the trees for debris do not step on anything unless you cannot avoid it, and again do not walk under any debris or broken branches.

Get in and get out as quickly as you can, if the cabin is not intact do not even bother going in, wait until someone gets there..

Crash sites are by there nature full of bad things. If a fire starts get out fast the fuel fumes will flash and can start other parts of the aircraft on fire, but it is ground soaked with fuel that will keep burning for a long time and is very hard to put out you will not be able to stop a fire with a hand held fire extinguisher.