, a Piper Navajo, was proceeding northbound at 6000 feet, estimating La Ronge at 2105Z. At 2052Z, ABS 203, a Beech 1900 of Athabaska Airways was cleared to Prince Albert airport via La Ronge direct, maintain 5000 feet, depart Runway 35, turn left and track outbound on the La Ronge 188 degree radial, and to expect higher. This clearance was issued by North Low Data and relayed through the La Ronge FSS. North Low Radar instructed C-GUNP
to maintain the La Ronge 173 degree radial. ABS 203 departed La Ronge at 2055Z, reported level at 5000 feet on initial contact with North Low Radar and was then cleared to maintain 15,000 feet, climb from 5000 feet to 7000 feet established on the La Ronge 188 degree radial and cross 20 DME at 5000 feet. The pilot read back the clearance but instead of reading back "cross 20 DME at 5000 feet", the pilot read back "cross 20 DME at 15,000 feet". North Low Radar did not pick up this discrepancy and advised the pilot the readback was correct, report leaving 7000 feet. About 40 seconds later, the pilot reported out of 7500 feet. North Low Radar queried the pilot immediately and after determining what had occurred, issued a revised clearance to ABS 203. Based on DME checks that North Low Radar requested after the problem was discovered , it is estimated that the two a/c were approximately 5 to 6 miles from passing each other when ABS 203 reported out of 7500 feet. A later DME check revealed that both a/c were within 1 mile of passing each other when ABS 203 was through 9000 feet (i.e. C-GUNP
at 12 DME, ABS 203 at 11 DME). The North Low Radar Controller was removed from duty.