VOR approaches

[Guest]

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Hi all

Much mention was made of VOR approaches in the recent thread "Approach
Course".

Apart from the lack of glideslope information do VOR approaches differ
in any way from ILS landings? The only problem I can foresee would
occur if the VOR beacon was (were?) sited some distance away from
landing zone.

Cheers
James

 

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Archived from groups: alt.games.microsoft.flight-sim (More info?)

James Hodson <jUNDERSCOREhodson@ntlworld.com.invalid> wrote:

> Apart from the lack of glideslope information do VOR approaches differ
> in any way from ILS landings?

VOR approaches differ in a few ways. First, a VOR signal is not nearly as
accurate as a localizer signal. Because of this, when tracking a VOR the
CDI needle can occasionally oscillate due to reception problems. Contrast
this with the normally rock-solid stability of the CDI under the influence
of a localizer signal (assuming inbound on the final approach course).

Secondly, due to the less accurate signal and the lack of a glideslope, the
minimums for VOR approaches are almost always going to be higher, sometimes
much higher. In other words, the altitude below which a pilot must not
descend is going to be higher and the visibility much greater when flying
VOR approaches. This often is the difference between getting into an
airport on the approach and having to go missed to fly off to the alternate
airport.

Finally, the fact that there is no glideslope means the pilot must "step
down" to lower altitudes along the VOR approach, rather than set up a
nicely stabilized, 3 degree, constant descent. Stepping down requires
flying level for x number of miles, then dropping at 700 to 1000 feet per
minute to the next lower altitude, followed by another straight and level
flight for another x number of miles.

When in the clouds and/or poor-to-no visibility, most pilots surveyed would
most likely prefer the stabilized, constant descent of an ILS versus the
non-stabilized descent/level off of a non-precision approach, such as a VOR
approach. I recall reading that the US aviation accident reports back this
up. There are more accidents when an aircraft is flying a non-precision
approach versus an ILS approach.

--
Peter


















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Archived from groups: alt.games.microsoft.flight-sim (More info?)

James wrote:

> I suppose I was subconsciously referring to clear-weather approaches.


In the US, aircraft that are flying under an IFR flight plan have to
terminate their flight with some type of an approach to the runway. If
the weather allows pilots to see the airport and remain clear of clouds
whole flying to the airport, pilots can request a visual approach,
which usually shaves several minutes off the final phase of the flight.
Often, ATC will offer these, too, since it eases their workload by
reducing traffic separation minima.

A visual approach allows a pilot to navigate visually to the airport,
fly the most convenient route to align with the runway (be it fly
straight in or fly a modified traffic pattern), and descend at pilot's
discretion. Certainly much less restrictive than an ILS, VOR, or any
other instrument approach.

The caveat when flying a visual approach is that, once cleared for a
visual approach, the pilot is now responsible for their own terrain and
IFR traffic separation.

There are times when even in clear weather, ATC will assign an
instrument approach, such as an ILS or a VOR approach, for an aircraft
to fly. This is often done during busier times or at very consistently
busy airports where the sequencing of aircraft into the airport is more
valuable than the easing of ATC workload.

--
Peter

 

[Guest]

Archived from groups: alt.games.microsoft.flight-sim (More info?)

Whoops, "whole" should be "while" in the first paragraph of my previous
post.

--
Peter

 

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Archived from groups: alt.games.microsoft.flight-sim (More info?)

On Fri, 6 May 2005 22:33:10 -0400, pr <nope@nospam.com> wrote:

>James Hodson <jUNDERSCOREhodson@ntlworld.com.invalid> wrote:
>
>> Apart from the lack of glideslope information do VOR approaches differ
>> in any way from ILS landings?
>
>VOR approaches differ in a few ways. First, a VOR signal is not nearly as
>accurate as a localizer signal. Because of this, when tracking a VOR the
>CDI needle can occasionally oscillate due to reception problems. Contrast
>this with the normally rock-solid stability of the CDI under the influence
>of a localizer signal (assuming inbound on the final approach course).

[SNIP info]

Hi Peter

Many thanks for all that.

I suppose I was subconsciously referring to clear-weather approaches.
Neverthess, the details about the needle being less sensitive and
moving about were informative. Ditto re the stepping down. I guess
that an approach chart is most definitely required for VOR approaches
🙂

Cheers
James

 

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Archived from groups: alt.games.microsoft.flight-sim (More info?)

On 9 May 2005 11:38:57 -0700, "pr" <proffice@twcny.rr.com> wrote:

>Whoops, "whole" should be "while" in the first paragraph of my previous
>post.

Visual typo here. I read whole as while. The brain power of the less
than average simmer, eh? ;-)

James

 

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Archived from groups: alt.games.microsoft.flight-sim (More info?)

On 9 May 2005 11:29:55 -0700, "pr" <proffice@twcny.rr.com> wrote:

>A visual approach allows a pilot to navigate visually to the airport,
>fly the most convenient route to align with the runway (be it fly
>straight in or fly a modified traffic pattern), and descend at pilot's
>discretion. Certainly much less restrictive than an ILS, VOR, or any
>other instrument approach.

More thanks, Peter.

Most of the time I quite enjoy flying as instructed by ATC as it makes
me fly more accurately - Qulling excepted, of course. Or should that
be flying off course? <evil smirk>

Naturally, in saying the above I'm assuming that I'm flying manually,
with the auto pilot truly and firmly switched off.

James