Originally Posted by
LOWI
Consider the following scenarios:
a) Loss of RNP capability before starting an RNP approach
b) Loss of RNP capability before reaching the FAF
c) Loss of RNP capability on final approach
For A, you can't start the approach and must fly a different type of approach.
For B and C, you can only continue if you have the runway in sight, otherwise you must go around.
Am I right with this or am I having a brain fart?
Having mastered the good old days of NDBs, I just want to remind myself about the technological advances in this industry.
Summary, for A,B or C...
If you have RNP capability, fly the approach
If you are visual and can maintain it, you can fly a visual approach (why couldn't you prior to the FAF?)
If you're not visual, do something else!
G/A's - Our RNP for the approach is normally significantly higher than for the G/A's. Thus if our ANP falls below RNP (assuming not visual) we G/A and the RNP required goes up. In the absence of updating, our ANP usually falls at a slow rate (thus remaining inside the G/A RNP) and inside that time we can get to a suitable place that we can continue safely conventionally. That's for an aircraft with IRU's etc... If you're in a G/A aircraft I've no idea!