The phrase "a key problem when" is correct and usable in written English.
It can be used to introduce a significant issue or challenge that arises in a specific context or situation.
Example: "A key problem when implementing new technology is resistance from employees who are accustomed to the old systems."
Alternatives: "a major issue when" or "a critical challenge when".
High temporal and spatial variability is a key problem when quantifying methane emissions from soils.
A key problem when optically scanning machined surfaces for error measurement is noise and localised data gaps due to reflectance.
However, thruster cavitation was raised as a key problem when using thrusters for a purpose for which they were not intended.
Barbara Otto is chief executive of Think Beyond The Label, a US non-profit organisation that aims to help businesses overcome a key problem when hiring disabled people: sheer confusion.
For instance, low adherence has been reported as a key problem when treating young clients in community settings.
Complexity is a key problem when visualizing biological networks; as the number of entities increases, most graphical views become incomprehensible.
I possess very good listening skills, am not afraid to ask questions, and am extremely straightforward, acting as a key problem solver when issues may arise.
The determination of these rules and membership functions is one the key problems when designing fuzzy controllers, and is generally affected by subjective decisions.
Convergence and computational complexity of the SpeMD procedure are key problems when this method is applied to large complex networks.
A key problem is gauging when regulators might interfere, specifically how interference decreases with a diminishing correlation between these regulators and thus deciding how to select which regulators to use in the regression.
Pipeline and infrastructure shortages towards accessing natural gas, upon which the New England states have become increasingly reliant, showed itself to be a key problem in the winter of 2013, when gas shortages in the Boston area and elsewhere led to severe price spikes.
