What is SUBLO (Subject to Load) in Aviation ?

14/05/2021 M.Durgut 1712 Views airplane, Subject to Load, SUBLO

Airplanes may encounter different conditions on each flight. And because of these various conditions, airplanes have to fly on some flights without selling all their seats. These seats are subject to load – SUBLO.

In other words, the seat blocks made when the planes cannot fly at full capacity due to the constraints they encounter due to various reasons are called subject to load.

SUBLO - Subject to Load — Subject to Load

Aircraft may face these constraints for many reasons. The altitude of the destination airport may be a reason for this. Besides, many meteorological conditions can cause subject to load application. Or, balance calculations and adjustments, which are an important issue of load and operation, can also cause a constraint on the load and passenger balance of an aircraft.

Think of it like a restaurant holding extra tables until they see how busy it gets. If the flight needs them, your SUBLO seat becomes available. If not, it stays blocked, and you might get bumped up to a better seat – score!

Why SUBLO? Airlines juggle weight and balance, sometimes limiting passengers to keep the plane within safe limits. Weather, cargo needs, even last-minute VIP bookings can trigger SUBLO.

So, what happens to you? Relax! You still have a confirmed seat, just on standby. The airline will keep you updated, and if your SUBLO seat opens up, you’ll be contacted to choose a new one.

The seats marked in red in the figure below are set as sublo and closed for sale. Sometimes the amount and distribution of cargo loads may also require subject to load.