the screen for the final and missed approach segments. If lateral clearance from any obstacle will be less than 1 nm, you should either approach to a nearby target structure and proceed visually, or make the approach from another direction leading to a circling manoeuvre. Minimum Descent Height (MDH) This is determined from a radio altimeter. It must be at least 200 ft by day and 300 ft by night. The MDH for an approach leading to a circling manoeuvre shall be at least 300 ft by day and 500 ft by night. Minimum descent altitude (MDA) May only be used if the radio altimeter is unserviceable, and shall be at least MDH + 200 ft, based on a calibrated barometer at the Operational Procedures 69 destination or the lowest forecast QNH for the region. Decision range (DR) At least ¾ nm unless you can convince the CAA otherwise. Visual reference You cannot continue an approach beyond DR or below MDH/MDA unless you are visual with the destination. Single pilot operations The MDH/MDA for a single-pilot ARA shall be 100 ft higher than the above—DR is not less than 1 nm. An ARA to a rig or vessel under way is only permitted for multi-crew. Heliport Minima for VFR/IFR, Onshore/Overwater When VFR, if you are slow enough to see other traffic and obstacles in time, that is, get a 1 minute visual reference ahead at 120 knots, the inflight visibility should be at least 2 nm. Out of sight of land, flight visibility must be at least 1500 m during daylight and 5 km by night. VFR En-Route Minima Helicopters On land, helicopters should have a minimum cloud-base of 600 feet agl (1500 feet at night) and 1000m visibility (3 km). In reduced visibility, adjust your airspeed to maintain a 1- minute visual reference ahead, e.g. at 120 knots, the inflight visibility should be at least 2 nm. A US Army study indicates that it takes about 5 seconds to perceive a problem, make a decision and start a correction. At 80 kts TAS, therefore, you will move 676 feet and get still closer as you turn away from an obstacle, the distance being equal to the radius of the turn which, in this case, would be 984 feet, assuming 30 degrees of bank, giving you a total distance of 1660 feet to cope with, which is not good if your visibility is only 1000 feet! So, in bad weather, slow down, certainly enough to give you a 2- minute visual reference. Flying VMC on top of cloud is not allowed because performance rules require that, if an engine fails, you must remain in sight of the surface, and be able to carry out a safe forced landing, but in twins it may be undertaken by non-Instrument Rated pilots if the cloud within 10 nm of the destination is forecast to |