Stabilised Approach Speed Tolerance
Among other things, the Boeing 737 (Classic) Flight Crew Training Manual recommends that at (1000 ft IMC and 500 ft VMC) final stabilisation height, the airspeed should not be more than VREF +20 IAS and not less than VREF.
I can understand the logic of "not less than VREF", but a IAS of 20 knots (when it is not required operationally) above VREF at 500 ft is really stretching the friendship especially if the runway is wet.
I realise that VREF +20 is the certified upper limit where an unacceptable risk of exceeding the certified landing distance for the weight is possible, but if the +20 knots is the result of incompetent handling or a unexpected wind gust, then no way would I have thought this speed would meet the spirit behind a calm day stable approach criteria.
There are operators who publish their stabilised approach airspeed criteria as no more than 10 knots above the selected approach speed, or less than 5 knots above the selected approach speed. That sounds reasonable to me. In other words, in no wind conditions, a speed of VREF say at 500 ft would be within the tolerance and no support call-out is required.
The FCTM states that the recommendations published (in this case for speed tolerances) are consistent with criteria developed by the Flight Safety Foundation. That maybe so, but the +20 knots (unless operationally required) part seems a a bit too liberal for my liking.
Appreciate if readers could give any examples of other B737 operator's definition of stabilised approach speed criteria to see how it compares with the Boeing recommendations. And if different to the FCTM figures, why?