Blocked Space Agreement

A blocked space agreement (BSA) is a commercial arrangement in which one airline purchases a guaranteed number of seats on another airline's scheduled flights, taking on the inventory risk for those seats in exchange for a discounted wholesale price.

What Is a Blocked Space Agreement?

In a blocked space arrangement, the purchasing airline — sometimes called the space buyer — acquires a fixed block of seats on the operating carrier's flight, typically weeks or months in advance. The space buyer then sells those seats to its own customers, potentially under its own flight number via a codeshare, or as part of a packaged product. The operating carrier receives guaranteed revenue for the block regardless of whether the space buyer fills all the seats.

BSAs differ from codeshare seat inventory access in the degree of commitment. A standard codeshare gives the marketing carrier access to available inventory at time of booking. A blocked space agreement gives the marketing carrier a dedicated, pre-purchased allotment, carrying inventory risk.

How It Works in Practice

A regional airline or charter operator may not be able to justify operating its own aircraft on a thin route connecting a small city to a major hub, but can negotiate a blocked space agreement on an existing mainline service. It buys, say, 20 seats on each departure and distributes those seats through its own sales channels — potentially at a premium to the wholesale cost if demand supports it.

Airlines also use BSAs within codeshare relationships. One carrier guarantees to purchase a minimum number of seats on a partner's flight; in return, the operating carrier holds that block and does not release it to the general market until close-in, when unsold seats may revert to open inventory.

BSAs are common in cargo as well, where airlines reserve belly capacity on passenger flights or purchase block space on dedicated freighters.

Why It Matters

For the operating carrier, blocked space agreements provide revenue certainty and load factor guarantees on flights that might otherwise carry demand risk. For the purchasing carrier, BSAs enable network extension without aircraft commitment, though they introduce yield management risk — if demand is weak, the space buyer absorbs losses on the purchased seats.

Key Facts and Figures

• BSAs typically specify a "sell-back" window — a date before departure when unsold blocked seats revert to the operating carrier's inventory.
• Cargo BSAs are widely used by integrators like DHL and freight forwarders on both passenger and freighter aircraft.
• BSAs may carry minimum purchase commitments expressed as a percentage of the block (e.g., the buyer pays for at least 80 percent of the block even if only 60 percent is sold).
• Airlines in thin markets — such as inter-island routes — rely heavily on BSAs to maintain frequency without overcommitting capacity.

Related Concepts

Codeshare Agreement, ACMI Lease, Interline Agreement, Capacity Purchase Agreement, Wholesale Ticket