Method for casting longitudinal cast products comprising: casting longitudinal cast products in a semi-continuous manner using a direct chill casting apparatus having a mold, wherein the mold has top and bottom openings and is configured to at least partially solidify molten metal, wherein the metal is molten aluminium or molten aluminium alloy, that is entered into the mold via the top opening and to output the cast product via the bottom opening, recording a thermal image of the cast product that is output via the bottom opening, determining at least three non-overlapping temperature ranges comprising a first temperature range, a second temperature range and a third temperature range, determining a peak temperature in the thermal image; comparing the peak temperature with the at least three temperature ranges; and a.) when the peak temperature is comprised in the first temperature range, casting the cast product, b.) when the peak temperature is comprised in the second temperature range, displaying an information indicative of a maintenance requirement of the casting apparatus and carrying out maintenance of the casting apparatus after the cast product is cast and before a subsequent casting operation is carried out, c.) when the peak temperature is comprised in the third temperature range, aborting the casting of the currently cast product and displaying an information indicative of an emergency shutdown, wherein the first temperature range comprises temperatures up to but not including 70°C, wherein the second temperature range comprises temperatures between 70°C and 90°C, and wherein the third temperature range comprises temperatures higher than and not including 90°C. casting longitudinal cast products in a semi-continuous manner using a direct chill casting apparatus having a mold, wherein the mold has top and bottom openings and is configured to at least partially solidify molten metal, wherein the metal is molten aluminium or molten aluminium alloy, that is entered into the mold via the top opening and to output the cast product via the bottom opening, recording a thermal image of the cast product that is output via the bottom opening, determining at least three non-overlapping temperature ranges comprising a first temperature range, a second temperature range and a third temperature range, determining a peak temperature in the thermal image; comparing the peak temperature with the at least three temperature ranges; and a.) when the peak temperature is comprised in the first temperature range, casting the cast product, b.) when the peak temperature is comprised in the second temperature range, displaying an information indicative of a maintenance requirement of the casting apparatus and carrying out maintenance of the casting apparatus after the cast product is cast and before a subsequent casting operation is carried out, c.) when the peak temperature is comprised in the third temperature range, aborting the casting of the currently cast product and displaying an information indicative of an emergency shutdown, a.) when the peak temperature is comprised in the first temperature range, casting the cast product, b.) when the peak temperature is comprised in the second temperature range, displaying an information indicative of a maintenance requirement of the casting apparatus and carrying out maintenance of the casting apparatus after the cast product is cast and before a subsequent casting operation is carried out, c.) when the peak temperature is comprised in the third temperature range, aborting the casting of the currently cast product and displaying an information indicative of an emergency shutdown, wherein the first temperature range comprises temperatures up to but not including 70°C, wherein the second temperature range comprises temperatures between 70°C and 90°C, and wherein the third temperature range comprises temperatures higher than and not including 90°C.