TangoAlphad said;
Loganair usually go for the visual if the weather permits but it seems that Flybe weren't allowed to do visuals as they made a habit of only doing the procedure onto 09 even on a gin clear day and 10 kts straight down 27..
I played back a few recent LC D328 approaches on FR24. Most appeared to be visual approaches to Runway 27 but I noticed that Monday morning's arrival from STN did what was presumably an ILS approach to 09 with a significant tailwind (circa 15-20kts?). (There is currently no ILS on runway 27 at DND).
I also noticed that, although the D328 appeared to follow the Cat C approach initially, the turn on to base leg was much tighter than the approach chart meaning that it stayed well clear of Scone. Base leg roughly followed the south slopes of the Sidlaws giving 6 or 7 mile finals and thereby reducing the risk of Scone traffic conflicts and of terrain affecting the ILS. The first time around the pattern, the D328 maintained the prescribed 2,200ft and didn't attempt an approach, instead climbing straight ahead to 3,000ft which is the standard missed approach procedure. The second time around the approach was sucessful.
If Flybe's Q400s were following the 09 ILS approach chart for Cat C aircraft, they would almost overfly Scone and base leg would be to the north of the Sidlaws. This increases the risk of terrain affecting the ILS if the approach is not stable and accurate. It also increases the risk of potential traffic conflicts with VFR traffic at Scone. These risks are managed via existing procedures but may not be compatible with Flybe's SOPs from what others have said. This routing also increases the risk of turbulence from the Sidlaws affecting the stability of the approach and potentially causing loss of ILS.
The 09 ILS approach has the following warning;
Due to terrain, LOC and GP flag alarms may be experienced at northern edge of coverage when below glidepath sector. Full scale fly-up indications may not be maintained when left of centre-line and below GP.
With the Q400 having a circa 170kt initial approach speed in icing conditions and with some (many?) Flybe approaches to 09 having had a tailwind component and, given the potential for turbulance from the Sidlaws, would this, ideally, necessitate a longer final approach and take the flight-path beyond Scone? If finals are extended at the normal 2,200ft then presumably this increases the risk of ILS being masked by terrain.
Is 09's length a limiting factor for a Q400 at DND with a significant tailwind component and especially in icing conditions with the associated higher speeds? I don't have access to detailed performance figures for the Q400 but the publicly available data that I have seen would seem to indicate that a Q400 carrying out an ILS approach and landing on 09 at DND with a tailwind component and icing conditions would, at best, create a high workload and may necessitate a diversion.
Is there any reason, other than cost, why DND doesn't have ILS on runway 27 (the runway most closely aligned to the prevailing wind)? The approach to 27 cuts through the Leuchars MATZ but this is the case whether the approach is visual, IFR or if ILS is added. There is also a danger area (D604) at 7nm DME which is presumably associated with the MOD ranges at Barry Buddon. An ILS approach to 27 would come very close to this Danger Area. Is this the reason for the absence of ILS on 27?
http://www.nats-uk.ead-it.com/public...temid=103.html