View Full Version : LHR AM 24th: +RA, RVRs and LVPs
wiggy
25th Sep 2007, 14:11
A question for our friends in the tower at LHR (and well done yesterday).
We arrived back at LHR yesterday ( 24th Sept) AM and ended up on the approach to 27 Left just as the weather deteriorated rapidly from the West. Tower were commendably quick in calling out the RVRs :eek:. During the Flightdeck tapdance as to what we could or couldn't do, and who could do what with what we asked if LVPs were in force ( well, we felt we had to at least ask :confused:). The reply was, as I remember it: " No, they're not in force, the RVRs are not due to the visibility, they're due to the heavy rain".:confused::confused:.
For my future reference, just how quickly can you get LVPs in Force at LHR and can anyone remember if LVPs have ever been in force anywhere purely due to rain?
I'm confused! What causes the low visibility is surely immaterial. Rain is just thick water droplets unlike fog which is thin ones. I suspect that the LVP's were not in force because it all happened a bit quickly and maybe unexpectedly (the drop in vis I mean).
I await a reply from a Heathrow Skygod for the definitive answer.
A I :}
wiggy
25th Sep 2007, 14:48
A I
Exactly - the LHR TAF yesterday AM certainly predicted the strong winds but the worse vis. was a TEMPO of 1500 metres in +RA so there was no reason for any thoughts of LVPs... until it all turned 'orrible just after we came off Lambourne.. Never mind, at least the roof of my house is still on:}
Geffen
25th Sep 2007, 16:58
I heard RVR's around the 300m mark and it takes about 45mins to get the 'field ready for LVP's
Gonzo
25th Sep 2007, 17:00
What were the RVRs? If not less than 600m then LVPs shouldn't have been in force.
If less than 600m, but safeguarding had not been completed (takes up to half an hour, maybe longer, during the day), then LVPs cannot be initiated as ILS protection cannot be guaranteed.
autothrottle
25th Sep 2007, 18:50
Gonzo old chap, explain what safegaurding is.... i'm just leaving for night shift so have no time to expla:{...
Gonzo
25th Sep 2007, 19:17
For anybody wondering, and I know there are many, I'm not quite completely senile yet, Geffen and I posted at the same time.
Honest.
Geffen
25th Sep 2007, 19:35
Gonzo,
Senile, you? I figured you took early retirement!
Weather yesterday at LL was impressive came and went in a matter of minutes but so dark the AGL was switched back on.
Gonzo
25th Sep 2007, 20:40
Ahhh, lovely.
One does choose the most opportune moments to take leave. :}
wiggy
25th Sep 2007, 22:05
Didn't have time to write the RVR's down :} but as far I remember it:
Touchdown was 700 - 800 ish ( certainly above 550 :))
Midpoint was around 300 -400..
Rollout was either Not available or not a lot...
As Geffen has said it came and went in a matter of minutes, our concern was the midpoint RVR migrating to the TDZ...fortunately it didn't.
As I said this was not in the Forecast or the Trend in the METAR for that matter so we didn't expect LVPs to be on tap - just wondered about the timescale - thanks for the replies.
Regards.