This level took me awhile to figure out,but after you get how to do it its not that complicated.

1. Make a large room with enought space for a bomb to be dropped in(ie,make it about 1200 units long and 700 units high)and put some lights in it and a pad.
   
2. Put a start position, a trigger_multiple, a trigger_key,a target_help, an key_airstrike marker,and a viper.Call the viper something like "boom".make the trigger multiple target the trigger key and give the trigger key a target of "boom". And put the trigger_multiple right over the pad you made.
   
3. Make the trigger key have a item "key_airstrike_marker", and give the airstrike marker a target of "help1" and set the name of the target help to be "help1". Then give the target_help a message of "Place Airstrike Marker\non pad".
   
4. Make 3 path corners high in the air that lead across the level and give the 1st one a name of "t1" and target of "t2". Make the second have a name of "t2" , a target of "t3", and a pathtarget of "drop". Make the third have a name of "t3".
   
5. Then make a misc_viper_bomb,give it a name of drop, and give it a target of "hit", give it an angle and damage of your choice(not too high or youll kill yourself), and then put it in the exact same spot as the second path corner. Make a path corner close to the ground and give it a name of "hit".
   
6. Make the viper target "t1".
   
7. compile your level and try it out.

[DW]Maverick
Full sample .map, .bsp, and this text.