The following parameters have been recommended by The Flight Safety Foundation to define a stabilized approach. They should be met by 1,000 feet above touchdown in IMC conditions. ? The aircraft is on the correct flight path. ? Only small changes in heading and pitch are required to maintain the flight path. ? The speed of the aircraft is not more that Vref + 20 knots indicated airspeed and not less than Vref. ? The sink rate is no more than 1,000 feet per minute. ? The aircraft is in the proper approach and landing configuration. ? The power setting is no lower than the minimum specified for the type of aircraft. ? All briefings and checklists have been performed. All of these approach parameters must be met by 500 feet, including visual approaches. If your Standard Operating Procedures do not include parameters for a stabilized approach, The Flight Safety Foundation recommends that you use the parameters just listed. In a situation where you are unsure of your position such as an unexpected radio altimeter reading (in other words, a radio altimeter reading that is surprising or that does not agree with the pilots＇ expectations), a go-around should be called for. Always check altitude against range. ? You should not see radar altitudes less than 1,000 feet while on an instrument approach prior to (＇prior to＇ = before) the initial fix. ? You should never see radar altitudes of less than 500 feet between the initial fix and final approach fix. ? You should never see less than 250 feet past the final approach fix unless you are on an approach with lower minimums or until going visual. Pre-planning and a good approach briefing will allow you to make a timely go-around decision when ? weather is having a significant impact such as the loss of visual reference, or ? there is a significant cross wind, head wind, tail wind or wind shear.5. The phrase always check altitude against range means （ ）.