Meet Ness at the Crash Site

Meet Ness at the Crash Site is a miscellaneous quest in Fallout 4. This quest is obtained when interacting with Ness during her random encounter.

Quick walkthrough
Ness will hire the Sole Survivor as a mercenary to clear Skylanes Flight 1981 of raiders, offering to split the loot. Multiple Interactions can be performed to increase the amount of "loot" she splits.

Detailed walkthrough
In a random encounter, a mysterious woman named Ness will ask you to secure the airliner that has a secret compartment used by smugglers, and filled with loot. The only problem is the airliner is populated by raiders. Along with some mercenaries Ness hired, the Sole Survivor will secure the area. Ness and her hired Gunner mercenaries will be located under the right wing of the Skylanes Flight 1981, located a few meters north of the intersecting roads.

After talking to Ness, the player character will get some caps from her. However, the player character can ask Ness what is in the compartment for a speech check. It is then revealed that Ness planned to keep the loot all to herself. If the Survivor tells Ness that she can't keep all the loot, she will tell the mercenaries, who don't know her plan, that the player character planned to take their share of the loot. Then both Ness and the mercenaries will be hostile. Once you kill Ness, there will be a key that belongs to the safe on her corpse. Now the player can take whatever they want or need from the safe.

Opening the safe at the end of the dialog options will prompt Ness to yell "Thief!", at which point she and the mercenaries become hostile. Of note is that the contents of the safe are green at this point.