[jhb_airlines] Re: Last night on FPI

  • From: Gerry Winskill <gwinsk@xxxxxxx>
  • To: jhb_airlines@xxxxxxxxxxxxx
  • Date: Thu, 29 Sep 2005 17:12:15 +0100

With GA aircraft I never lock onto the ILS but fly it manually. In heavier metal I use APPR, disable Autothrottle as soon as it has stabilised on the glideslope, then disengage AP at about 3 to 5 DME. Last night there was so much wind sheer on finals that ILS was having a hard time. I switched it off, which was "interesting". I find staying on the centreline, manually, when being bounced around, easier if I use 1.5 zoom.
Luckilly, and I'm sure FS9 becomes less realistic, strong crosswinds and windshear usually seem to disappear with about half a mile to run. I wonder why?


Gerry Winskill
gwinsk@xxxxxxx


Bones wrote:

The latter. All it is doing is sensing the localiser signal and turning towards it until any deviation is corrected. It will do this whether the wind is 20kts or 90kts (given enough time) and the final heading it settles on is irrelevant to its logic.
The AP is good enough to sense the decreasing and backing wind as you descend and it will be making constant corrections to actual heading but it can get a bit stressed in gusty conditions. If the gusts are short and sharp - nasty for the crew and pax - but not long enough to displace you much from the centreline then the AP will cope quite well. It is the longer gusts (or wind shear) that make it work a lot harder.
The weather was grim over quite a large area last night. Alex had nasty wind going into Valley and there was some awful wind shear approaching ROSUN around FL90 - as Tom and Gerry both found out that hard way. FSMeteo and the like do quite well in this respect considering they are only getting 30 min actuals. In real life this is the standard time between reports but it the weather is changing rapidly (it qualifies for what Met call a Significant Change) then the reports are made more frequently - in really bad weather being updated almost constantly.
These Special Reports don't get transmitted. It takes about 15 min for a normal METAR to reach the big wide world and this is just too slow to distribute Special Reports. Instead it is the controller who will advise pilots of the rapidly changing situation - or it may go out on local ATIS if this is an automatic unit.
If a front goes through then the weather can change very quickly indeed - and this is what happened at Manchester last night. The vis would have improved over 20 min or so but the METAR's jumped from 3500m to 9999m instantly. I'd been watching more up to date weather and I was able to tell Tom in advance that a significant change was on the way. Trouble is that I couldn't predict when FSMeteo or VATSIM would pick this up and change it in the sim..
bones


    -----Original Message-----
    *From:* jhb_airlines-bounce@xxxxxxxxxxxxx
    [mailto:jhb_airlines-bounce@xxxxxxxxxxxxx] *On Behalf Of
    *FrankTurley@xxxxxxx
    *Sent:* 29 September 2005 08:49
    *To:* jhb_airlines@xxxxxxxxxxxxx
    *Subject:* [jhb_airlines] Last night on FPI

It was a good session last night, I managed 2 hops, Aberdeen to a
wet wet Newcastle, and from there onto a wet, wet, Manchester. On
approach to Manchester the Baron's A/P struggled to hold the ILS
in that wind, which prompted a question for you experts from this
humble bean counter -
Is the A/P "smart" enough to be proactive in a cross wind and take
an appropriate heading, or does it just react to being off centre
and steer to get back on again?
Frank T. JHB167



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