Having experienced interesting and wide ranging views on Vref + 20, perhaps the original issue of Boeing’s change to Vref + 15 might be clarified.
So far there are suggestions of ‘no benefit’ from a previous value, #8, which cynically could be the ‘lawyers’ reduction of exposure to overrun accidents, as #11. Alternative reasons range from modifications, to having new data.
Can anyone comment if the latest aircraft variants are more ‘slippery’ on the approach - take longer to slow down. How long (time distance height) would it take to reduce speed from +20 to +15, (or nearer Vref) to establish a stabilised approach before 500ft - using a realistic procedure?
Are there any modifications associated with the recommended new max approach speed?
Is the change a crew/training manual amendment or a special notification; was there any accompanying explanation?
Are these changes linked to the use of FOLD for landing data - any changes to tables of ‘actual’ landing distances, thus coming in line with FAA (world) recommendations?
It’s not only interesting to know the reason behind the change, but also to be aware that with change there is opportunity for new risks to emerge from the change itself; someone somewhere might get ‘it’ wrong. Wrong version, wrong time place etc; knowing why might just help avoid those situations.