The landing strip theory is pretty much dead in academic circles, has been for decades really. The lines are only about 10-30cm deep in most places, nowhere near structurally capable of supporting any kind of aircraft even a lightweight one, and the Nazca soil would have just churned up immediately under any kind of landing stress.
What I find more interesting is the ceremonial procession theory, that people actually walked the lines as part of religious ritual. That one has much more physical evidence behind it. Maria Reiche spent like 40 years documenting them and she leaned astronomical, which still has some merit for certain formations.
The alien landing strip angle gets pushed hard in documentaries because its good telly, but nobody whos actually studied the archaeology takes it seriously anymore. Doesnt mean the lines arent genuinely mysterious - they absolutely are - just that the explanation is almost certainly deeply human and cultural rather than extraterrestrial. Be curious what others think about the water/irrigation ritual angle, that one seems underrated to me.