Been in engineering management for 15+ years and have been on both sides of a lot of loops. Went through LM's process for a principal-level role last fall and want to share what I noticed about how they run behavioral interviews, because it's genuinely different from the pattern I've seen at commercial tech companies.
The values they actually probe LM is deliberate about certain themes. Based on my loop across three different interviewers, the consistent threads were: Safety and ethics. Not just 'how did you handle a conflict' but 'describe a time you raised a safety concern and what happened.' They want to know if you'll actually speak up. Stakeholder management across hierarchy. Defense programs have unusual org structures. They want to know you can work with program managers, government customers, and program directors without getting lost in politics. Completing something through ambiguity. Long-cycle programs mean requirements shift. They ask about navigating changing specs. Technical integrity under pressure. Classic 'did you take a shortcut when you were under schedule pressure and what happened.'
Format Fully STAR. They signal this clearly in the prep materials they send ahead of the panel. Every question was 'tell me about a time...' They took notes during my answers. One interviewer stopped me after the Situation to say 'okay I get the context, what did YOU specifically do?' That's a good sign: they're checking for individual ownership, not team stories.
Question bank from my round Tell me about a time you had a technical disagreement with leadership and how you resolved it. Describe a project where requirements changed significantly mid-stream. Tell me about a time you identified a safety risk that others had missed. Describe a time you mentored someone. What was the outcome? How have you dealt with delivering bad news to a customer or stakeholder?
What flops Vague answers. 'We kind of figured it out as a team' is death. Also: answers that center on complaining about the situation rather than what you did. They don't want heroes who blame circumstance.
Prep specific STAR stories and know which ones you'll pull for ethics, conflict, and ambiguity questions.