Ballistic Descent Clearances
Firstly please let me stress that I have the highest respect for air traffic controllers and the superb work that they do.
But from time to time we do get asked to perform miracles! In bound to a certain UK airport today on descent and then we get cleared to FL 100 to be level at XXXX when we have got circa ten miles to go to XXXX and we are going through FL 150 - read back clearance and said we would do our best and then ATC replied, ok be level at XXXX plus ten miles. We made this (just) but a bit uncomfortable for pax with speedbrake and high speed etc.
We are used to having to achieve certain levels as specified on the arrival (expect to be FL 70 by SLP or FL200 25 before Monty, for example, but being given late clearances such as this which are difficult to achieve can be challenging. Most operators also have a requirement to reduce rates of closure to 1,000 ft per min when withing 1,000 ft of a cleared level to avoid TCAS alerts.
I would be interested to hear ATCs side of this - thanks for any help.