The Rockport Test is not a new thing and has been in use for years. As with the bike test, (relatively) low impact and no twisting are the main benefits, allowing testing of those with dodgy ankles or knees.
However, talking to one of the PTIs before XMas, my understanding is that the RAF is not employing this test in its pure form, but is measuring HR during the last quarter of the test rather than at the end. I don't have the details and will of course bow to someone with actual experience.
The test MUST NOT be conducted on a treadmill - it gives false results (more fails if memory serves).
As often, Google is your friend:
The Rockport Fitness Test
but as I say, the intention was to do it slightly differently. How many stations have 400m tracks for example? (3 I think). I haven't seen anything published on the subject. No doubt there's a DIN or something out there.
Edited to add that the indicative VO2max requirements are the same as before.