The transonic aerodynamics of a low pressure turbine (LPT) cascade, mimicking geared turbofan conditions during cruise, is currently under study using direct numerical simulation. In the first step of this endeavour, transition, separation and loss generation were examined at Mach 0.7, 0.9, and 0.95, with a constant Reynolds number of \(70\times 10^3\) based on the true chord, in clean inlet conditions. The aim is to identify the impact of sonic conditions and choking on self-induced transition, generated purely by flow features around the blade. The pressure distribution was slightly overestimated with respect to experimental conditions. Separation occurs over the suction side (SS) at \(58\%\) and \(69\%\) of blade length for the first two Mach numbers. Skin friction is low in the Mach 0.95 case, but unexpectedly separation does not take place for this case. The choking of the passage was considered as influencing factor. A supersonic region followed by a shock appears at Mach 0.9 or higher, and a fully choked passage is found at 0.95. Separation bubbles with turbulent reattachment are formed on the pressure side (PS) between \(0\%\) and \(50\%\) of the blade length. Separation on the SS was identified as laminar separation long bubble, while reversed transition develops on the PS after reattachment. Wake losses increase with higher Mach numbers, and turbulence is more prominent at lower Mach numbers. This investigation provides insights into the aerodynamic characteristics of the linear low pressure turbine cascade, addressing separation, transition, losses, and wake behavior in sonic conditions at low Reynolds numbers.