PURPOSE: To quickly and accurately inform an operator of operation category information by detecting the extinguished state of each lamp provided on a runway and comparing detection results and an operation category reference with each other and presenting the comparison result to the operator by a display part.

CONSTITUTION: When discriminating that some of lamps 7a to 7n is extinguished, a discriminating part 4 checks whether the extinguished lamp is an entrance lamp or not. If any of entrance lamps is extinguished, the discriminating part 4 calculates a proportion of extinguished lamps of entrance lamps and calculates a proportion of extinguished lamps of the other lamps independently of the extinguishment range and selectively reads out operation category reference information from an operation category reference file 3. This operation category reference information and respective calculation results are compared with each other, and comparison results are displayed on a display part 6.