Key cold-flow property for aviation turbine fuel: Which property is the most critical specification for a jet fuel due to the very low temperatures encountered at cruising altitude?

Introduction / Context:
Aircraft routinely operate at high altitude where ambient temperatures are far below 0°C. A jet fuel must remain free-flowing and free of crystallized solids in aircraft tanks and lines to ensure safe engine operation.

Given Data / Assumptions:

• Modern aviation turbine fuels (e.g., Jet A/Jet A-1).
• Long-duration cruise in cold-soak conditions.
• Focus on cold-flow safety rather than color or cosmetic attributes.

Concept / Approach:
The freezing point specifies the temperature at which solid crystals form sufficiently to endanger flow. It is the primary cold-flow limit used in jet fuel specifications. While cloud and pour points are relevant in diesel/fuel oils, jet fuel is governed most critically by freezing point for high-altitude service.

Step-by-Step Solution:

Verification / Alternative check:
Aviation fuel standards (e.g., Jet A-1) specify a maximum freezing point (around -47°C) as a critical requirement for safe operation.

Why Other Options Are Wrong:

Common Pitfalls:
Transferring diesel-fuel logic (cloud/pour point) to jet fuel without considering altitude-specific requirements.

Final Answer:
Freezing point