From: laubach@hpl.hp.com (Mark Laubach)
Subject: Re: help with ATC statement
Date: Thu, 7 Jan 1993 20:35:12 GMT
Organization: Hewlett-Packard Laboratories Palo Alto,CA
X-Newsreader: TIN [version 1.1.4 PL6]

You are *always* supposed to fly a square pattern *unless* prior
exceptions have been arranged.  It is a fundamental safety issue.
Downwind legs should be parallel to the runway, base should be at 90
degrees, and of course final should be dead on.  Crab as needed to
keep downwind parallel and the base at 90 degrees as seen by your
track over the ground.

ATC is providing traffic separation for other traffic, both landing
and taking off.  If you fly a standard pattern then they have a pretty
good idea of how much of a time gap there is before you land.  If you
do something they are not expecting, then you've created a safety
problem for them and for other aircraft.

The plane about to land has priority over traffic taking off.  ATC may
ask you to extend your downwind, or they may tell you that they'll
call your base turn, or they may even ask you to do a 360 degree turn
in the downwind leg for spacing (usually they tell you the turn
direction).  They may even tell you to go around just before you are
about to land.  360 degree turns should be done as a standard rate
turn (someone correct me if I'm wrong on this and also fill in the
details - brain is not working due to head cold) and the turn should
be made to the outside of the pattern (away from the runway).  ATC
should never ask a plane in the pattern to expedite landing - it puts
too much pressure on the pilot and is asking for trouble.  If they
tell you to go around, even when you are 10 seconds from landing, then
go around.

About *unless* above.  While in downwind, you can ask ATC for a "short
final" (e.g. "Cessna 12345, we'd like to request a short final on this
one") and they may or may not give you permission for it.  If there
are no other planes and the pattern ahead and if they don't want to
launch someone before you, you will probably get permission FOR THAT
PASS ONLY.  Requesting "short final" tells ATC that you are about to
do short field or power off landing practice.  In which case, they'll
expect rounded corners and the like. Otherwise, they are expecting a
standard pattern landing.  Also, if you want to do a practice go round
on final, then you'll need ATC permission also.

By the way, standard patterns don't just start in the downwind leg.
They start when you get in the plane.  If you doing pattern work, ATC
expects, unless otherwise directed, that your upwind leg will be
straight out and aligned with the runway, that your crosswind turn
will be 90 degrees to the runway and executed between 400 and 500 feet
AGL, and that your crosswind to downwind turn will be 90 degrees also.
Be aware of pattern altitudes at various airports.  The one I fly at
has 1000 ft AGL on one side of the airport and 800 ft AGL on the
other.  You are expect to observe the appropriate altitudes when doing
pattern work.  ATC may direct you to do otherwise, for example, extend
your upwind until a certain point in time or place.

Also, when you are at an airport that doesn't have an operating tower,
you are still responsible for flying a standard pattern *unless*
you've notified other pilots of your intentions *AND* it is safe to do
so.  For example, if everything is clear ahead of you, then you can
tell other pilots of your intentions "Blather Traffic, Cessna 12345
in the downwind for right traffic on 16, we'll be executing a short
final for practice power off landing, Blather Traffic".  This tells 
everyone in the air and on the ground what to expect.

Happy Flying!

--
Mark
PP-ASEL-G/AT






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