Just as a sidenote here with a BAe 146 / RJ100 (classed in the UK as a "Lower Medium" aircraft) following a 767 (classed of course as a "Heavy" aircraft) the minimum recommended spacing on the approach is 5 miles.
ATC will always try to acheive the correct spacing between arriving traffic. However, sometimes it just doesn't work out. If the RJ100 was less than 5 miles behind the 767, ATC would have informed the pilot of the RJ, and asked him if he was willing to continue with a spacing lower than the CAA recommend.
For example, I was flying into Gatwick in a 757 last week behind a Virgin Atlantic 747. Spacing on the approach was tight, and we had already been in a holding pattern for about 10 minutes. We were informed by the controller that we were following a 747, 3 miles ahead on the approach, with a recommended spacing of 5 miles, and he asked if we were "happy to continue".
We said yes, we usually do in this case. I have landed with 3 mile spacing in a 757 behind a 747 several times and it has never been a problem. But one thing is certain, the responsibility for getting flipped over by wake turbulence was then all ours. ATC had washed their hands of that scenario. If at 700ft above the ground we started to enter heavy wake, in all likelyhood we would go-around immediately.
My best guess is that the scenario above happened to the RJ100 crew. Maybe they did have the recommended spacing, who knows? Like I said wake voritces can remain much longer than usual in certain atmospheric conditions. Don't ask me what they are, I don't know. As far as I am aware even scientists don't really understand what causes them to be so prolonged in rare cases.
Anyway it was just something else that popped into my head on this one!
Hey that's what these forums are all about. Usually I learn something new on here every day too. That's one great thing about this industry, which even those who have been in it 25 years will tell you, you never stop learning.
I used to love the smell of Jet-A in the morning...