[jhb_airlines] Re: Flight Report - 037G

  • From: "Bones" <bones@xxxxxxx>
  • To: <jhb_airlines@xxxxxxxxxxxxx>
  • Date: Fri, 31 Dec 2004 15:16:37 -0000

A good question Phil but the answer isn't that straightforward these =
days.

It is more than likely that most airlines would indeed nominate BIRK as =
the
alternate airfield. This is economics overriding safety again but the =
basic
logic is sound. Most flights will indeed land at BIKF without having to
divert. Of the diverted aircraft a high proportion would probably land =
at
BIRK - only a very small percentage would have to go elsewhere.

If all these aircraft had nominated a diversion airfield back in Canada =
or
Europe the fuel load required would be huge and this would have a =
possible
impact on payload and definitely on performance. With BIRK as the =
alternate
airfield the fuel load would be substantially less. The effect of this =
is a
change in planning considerations by the crew.

The crew will have a good idea of the forecast weather in Iceland before
they depart. If the situation suggests that both airfields are likely to =
be
affected then the crew will be looking to see how long the weather is =
likely
to affect the region. In other words their priority is to look at the =
TAF's
rather than the METAR's - something we tend not to do in FS. They will
therefore alter their fuel plan depending on the TAF data. Choice one is =
to
add enough fuel to ensure a return to the mainland. Choice two would be =
to
uplift additional fuel sufficient to hold and await weather improvement.
Choice three would be to delay the flight.

I think a lot of pilots would opt for choice 2 and uplift additional =
fuel.
The amount would depend on the pilot and his experience of Icelandic
weather. Say he elects to add fuel for a further hour. This would allow =
him
to reach BIKF and hold for 01:45 before diverting to BIRK with =
experience
telling him that the weather may well clear in that time. Alternatively,
whilst en route and keeping up to date with the weather situation, the =
pilot
could fly for another 30 minutes towards Iceland before reaching a point =
at
which he must turn around and head back to Europe. Effectively this =
would be
the PNR (Point of No Return) because the reduced fuel carried would =
dictate
this should be calculated.

PNR may be calculated in the FMS but if not it's not too difficult a =
formula
to work out. A good web page for this is
http://www.airsafaris.com.au/general_info/pnrcp.htm as it tells you =
about
PNR and also about Critical Point. Critical Point isn't a fuel derived
calculation but a simpler formula to tell you if it is quicker to go on =
than
to turn back. I used it for all overwater flights (even from EGNS to =
EGGP)
and it made me feel good to know that if I hit a problem on the way I =
always
knew what action I needed to take.

bones=20

-----Original Message-----
From: jhb_airlines-bounce@xxxxxxxxxxxxx
[mailto:jhb_airlines-bounce@xxxxxxxxxxxxx] On Behalf Of Phil Reynolds
Sent: 31 December 2004 14:33
To: JHB
Subject: [jhb_airlines] Flight Report - 037G


Hi John,

JHB037B ENSN BIKF 1115 1414 2:59
A/C - B737 (PMDG)
Route - SOXUS UM725 FLS UG3 VALDI G3 SKARD

I've got a quick question regarding alternates.  With the flight above =
the
only "near" alternate is BIRK which is only 20 miles away, so I would
imagine that the chances are that if BIKF is closed BIRK is also closed.
Therefore when flying to remote airports do I factor in enough fuel to =
get
back again, and plan on landing with a heavy a/c if the original =
destination
is okay?  (I think I already know the answer!)

Cheers

Phil
JHB037G



Other related posts: