Complex sentence: Continuing to descend and approach, the aircraft reached its minimum descent altitude (MDA) of but both pilots expressed that there was still no visual reference to the runway or its approach lighting system due to the dense fog.
Split into simpler sentences: Continuing to descend and approach, the aircraft reached its minimum descent altitude (MDA) of. At this altitude, both pilots expressed that there was no visual reference to the runway or its approach lighting system due to the dense fog.