180 to 5
First: I do not blame ATC for the accident. Just to be clear.
Question: “180 to 5” is a well known procedure (or “demand”) by ATC world wide. I do expect that to be 180 to 5 (nautical) miles from threshold. Is that correct, or could it be interpreted as DME 5? At SFO, the latter means about a mile shorter as the VOR/DME equipment is half way down the runway. (I’m not a professional pilot by the way)
When you are supposed to be stable at 500 feet, which means 1,5 miles from threshold, A 180 to 5 DME (for SFO) means you have 2,5 mile to get stable. A friend of mine is a 737 (all of them) pilot, and he says “180 to 5 is OK, but with no time to spare”. “There is just enough time to put down final flap and complete landing checklist”, he says.
Now, is it absolutely clear that “180 to 5” means 5 nm from threshold? DME could be at the far end of the runway making “180 to 5 DME” pretty close…