Material Requirements Planning on an Aircraft Assembly Line

Key Takeaways

• Boeing's new 737 North Line will boost output to 52 aircraft/month.
• Rate‑based MRP schedules production using Manufacturing Days, not calendar dates.
• Multi‑level assembly requires backward scheduling for long‑lead components.
• System balances smooth demand with batch ordering and JIT delivery constraints.
• Planning software integrates lot‑sizing, safety stock, and capacity for stable PO flow.

Pulse Analysis

Boeing’s decision to launch the 737 North Line marks the first time in half a century that the 737 will be assembled outside the Renton complex. The new final‑assembly line, slated to start operations this summer at the Everett wide‑body plant, is a cornerstone of the company’s goal to lift monthly output from the current 42 aircraft to 52 by 2027. Adding a fourth line not only spreads production risk across sites but also pressures the supply chain to deliver parts with tighter timing and higher reliability.

The line relies on a rate‑based Material Requirements Planning (MRP) system that abandons calendar dates in favor of Manufacturing Days, a metric that aligns directly with the line’s 2.02 aircraft‑per‑day cadence. By counting forward from a target completion date, the system works backward through the bill of materials, pinpointing when long‑lead items such as landing‑gear trunnions must be released. This multi‑level, backward‑scheduling approach converts thousands of overlapping airplane requirements into a single, smooth demand curve that can be fed into production scheduling software.

Integrating lot‑sizing, blanket agreements, safety stock and capacity constraints, the planning software translates the smooth demand curve into a predictable flow of purchase orders. This mitigates the “lumpy” economics of bulk buying while preserving just‑in‑time delivery, a balance critical for aerospace suppliers who operate on thin margins and long lead times. For Boeing, the disciplined MRP execution reduces inventory holding costs and improves line reliability, while the broader industry watches as the model demonstrates how high‑mix, high‑volume aircraft production can be synchronized across distributed facilities.